/*------------------------------------------------------------------------- * * rewriteHandler.c * Primary module of query rewriter. * * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION * src/backend/rewrite/rewriteHandler.c * * NOTES * Some of the terms used in this file are of historic nature: "retrieve" * was the PostQUEL keyword for what today is SELECT. "RIR" stands for * "Retrieve-Instead-Retrieve", that is an ON SELECT DO INSTEAD SELECT rule * (which has to be unconditional and where only one rule can exist on each * relation). * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/relation.h" #include "access/sysattr.h" #include "access/table.h" #include "catalog/dependency.h" #include "commands/trigger.h" #include "executor/executor.h" #include "foreign/fdwapi.h" #include "miscadmin.h" #include "nodes/makefuncs.h" #include "nodes/nodeFuncs.h" #include "optimizer/optimizer.h" #include "parser/analyze.h" #include "parser/parse_coerce.h" #include "parser/parse_relation.h" #include "parser/parsetree.h" #include "rewrite/rewriteDefine.h" #include "rewrite/rewriteHandler.h" #include "rewrite/rewriteManip.h" #include "rewrite/rewriteSearchCycle.h" #include "rewrite/rowsecurity.h" #include "tcop/tcopprot.h" #include "utils/builtins.h" #include "utils/lsyscache.h" #include "utils/rel.h" /* We use a list of these to detect recursion in RewriteQuery */ typedef struct rewrite_event { Oid relation; /* OID of relation having rules */ CmdType event; /* type of rule being fired */ } rewrite_event; typedef struct acquireLocksOnSubLinks_context { bool for_execute; /* AcquireRewriteLocks' forExecute param */ } acquireLocksOnSubLinks_context; typedef struct fireRIRonSubLink_context { List *activeRIRs; bool hasRowSecurity; } fireRIRonSubLink_context; static bool acquireLocksOnSubLinks(Node *node, acquireLocksOnSubLinks_context *context); static Query *rewriteRuleAction(Query *parsetree, Query *rule_action, Node *rule_qual, int rt_index, CmdType event, bool *returning_flag); static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index); static List *rewriteTargetListIU(List *targetList, CmdType commandType, OverridingKind override, Relation target_relation, RangeTblEntry *values_rte, int values_rte_index, Bitmapset **unused_values_attrnos); static TargetEntry *process_matched_tle(TargetEntry *src_tle, TargetEntry *prior_tle, const char *attrName); static Node *get_assignment_input(Node *node); static Bitmapset *findDefaultOnlyColumns(RangeTblEntry *rte); static bool rewriteValuesRTE(Query *parsetree, RangeTblEntry *rte, int rti, Relation target_relation, Bitmapset *unused_cols); static void rewriteValuesRTEToNulls(Query *parsetree, RangeTblEntry *rte); static void markQueryForLocking(Query *qry, Node *jtnode, LockClauseStrength strength, LockWaitPolicy waitPolicy, bool pushedDown); static List *matchLocks(CmdType event, Relation relation, int varno, Query *parsetree, bool *hasUpdate); static Query *fireRIRrules(Query *parsetree, List *activeRIRs); static Bitmapset *adjust_view_column_set(Bitmapset *cols, List *targetlist); static Node *expand_generated_columns_internal(Node *node, Relation rel, int rt_index, RangeTblEntry *rte, int result_relation); /* * AcquireRewriteLocks - * Acquire suitable locks on all the relations mentioned in the Query. * These locks will ensure that the relation schemas don't change under us * while we are rewriting, planning, and executing the query. * * Caution: this may modify the querytree, therefore caller should usually * have done a copyObject() to make a writable copy of the querytree in the * current memory context. * * forExecute indicates that the query is about to be executed. If so, * we'll acquire the lock modes specified in the RTE rellockmode fields. * If forExecute is false, AccessShareLock is acquired on all relations. * This case is suitable for ruleutils.c, for example, where we only need * schema stability and we don't intend to actually modify any relations. * * forUpdatePushedDown indicates that a pushed-down FOR [KEY] UPDATE/SHARE * applies to the current subquery, requiring all rels to be opened with at * least RowShareLock. This should always be false at the top of the * recursion. When it is true, we adjust RTE rellockmode fields to reflect * the higher lock level. This flag is ignored if forExecute is false. * * A secondary purpose of this routine is to fix up JOIN RTE references to * dropped columns (see details below). Such RTEs are modified in-place. * * This processing can, and for efficiency's sake should, be skipped when the * querytree has just been built by the parser: parse analysis already got * all the same locks we'd get here, and the parser will have omitted dropped * columns from JOINs to begin with. But we must do this whenever we are * dealing with a querytree produced earlier than the current command. * * About JOINs and dropped columns: although the parser never includes an * already-dropped column in a JOIN RTE's alias var list, it is possible for * such a list in a stored rule to include references to dropped columns. * (If the column is not explicitly referenced anywhere else in the query, * the dependency mechanism won't consider it used by the rule and so won't * prevent the column drop.) To support get_rte_attribute_is_dropped(), we * replace join alias vars that reference dropped columns with null pointers. * * (In PostgreSQL 8.0, we did not do this processing but instead had * get_rte_attribute_is_dropped() recurse to detect dropped columns in joins. * That approach had horrible performance unfortunately; in particular * construction of a nested join was O(N^2) in the nesting depth.) */ void AcquireRewriteLocks(Query *parsetree, bool forExecute, bool forUpdatePushedDown) { ListCell *l; int rt_index; acquireLocksOnSubLinks_context context; context.for_execute = forExecute; /* * First, process RTEs of the current query level. */ rt_index = 0; foreach(l, parsetree->rtable) { RangeTblEntry *rte = (RangeTblEntry *) lfirst(l); Relation rel; LOCKMODE lockmode; List *newaliasvars; Index curinputvarno; RangeTblEntry *curinputrte; ListCell *ll; ++rt_index; switch (rte->rtekind) { case RTE_RELATION: /* * Grab the appropriate lock type for the relation, and do not * release it until end of transaction. This protects the * rewriter, planner, and executor against schema changes * mid-query. * * If forExecute is false, ignore rellockmode and just use * AccessShareLock. */ if (!forExecute) lockmode = AccessShareLock; else if (forUpdatePushedDown) { /* Upgrade RTE's lock mode to reflect pushed-down lock */ if (rte->rellockmode == AccessShareLock) rte->rellockmode = RowShareLock; lockmode = rte->rellockmode; } else lockmode = rte->rellockmode; rel = table_open(rte->relid, lockmode); /* * While we have the relation open, update the RTE's relkind, * just in case it changed since this rule was made. */ rte->relkind = rel->rd_rel->relkind; table_close(rel, NoLock); break; case RTE_JOIN: /* * Scan the join's alias var list to see if any columns have * been dropped, and if so replace those Vars with null * pointers. * * Since a join has only two inputs, we can expect to see * multiple references to the same input RTE; optimize away * multiple fetches. */ newaliasvars = NIL; curinputvarno = 0; curinputrte = NULL; foreach(ll, rte->joinaliasvars) { Var *aliasitem = (Var *) lfirst(ll); Var *aliasvar = aliasitem; /* Look through any implicit coercion */ aliasvar = (Var *) strip_implicit_coercions((Node *) aliasvar); /* * If the list item isn't a simple Var, then it must * represent a merged column, ie a USING column, and so it * couldn't possibly be dropped, since it's referenced in * the join clause. (Conceivably it could also be a null * pointer already? But that's OK too.) */ if (aliasvar && IsA(aliasvar, Var)) { /* * The elements of an alias list have to refer to * earlier RTEs of the same rtable, because that's the * order the planner builds things in. So we already * processed the referenced RTE, and so it's safe to * use get_rte_attribute_is_dropped on it. (This might * not hold after rewriting or planning, but it's OK * to assume here.) */ Assert(aliasvar->varlevelsup == 0); if (aliasvar->varno != curinputvarno) { curinputvarno = aliasvar->varno; if (curinputvarno >= rt_index) elog(ERROR, "unexpected varno %d in JOIN RTE %d", curinputvarno, rt_index); curinputrte = rt_fetch(curinputvarno, parsetree->rtable); } if (get_rte_attribute_is_dropped(curinputrte, aliasvar->varattno)) { /* Replace the join alias item with a NULL */ aliasitem = NULL; } } newaliasvars = lappend(newaliasvars, aliasitem); } rte->joinaliasvars = newaliasvars; break; case RTE_SUBQUERY: /* * The subquery RTE itself is all right, but we have to * recurse to process the represented subquery. */ AcquireRewriteLocks(rte->subquery, forExecute, (forUpdatePushedDown || get_parse_rowmark(parsetree, rt_index) != NULL)); break; default: /* ignore other types of RTEs */ break; } } /* Recurse into subqueries in WITH */ foreach(l, parsetree->cteList) { CommonTableExpr *cte = (CommonTableExpr *) lfirst(l); AcquireRewriteLocks((Query *) cte->ctequery, forExecute, false); } /* * Recurse into sublink subqueries, too. But we already did the ones in * the rtable and cteList. */ if (parsetree->hasSubLinks) query_tree_walker(parsetree, acquireLocksOnSubLinks, &context, QTW_IGNORE_RC_SUBQUERIES); } /* * Walker to find sublink subqueries for AcquireRewriteLocks */ static bool acquireLocksOnSubLinks(Node *node, acquireLocksOnSubLinks_context *context) { if (node == NULL) return false; if (IsA(node, SubLink)) { SubLink *sub = (SubLink *) node; /* Do what we came for */ AcquireRewriteLocks((Query *) sub->subselect, context->for_execute, false); /* Fall through to process lefthand args of SubLink */ } /* * Do NOT recurse into Query nodes, because AcquireRewriteLocks already * processed subselects of subselects for us. */ return expression_tree_walker(node, acquireLocksOnSubLinks, context); } /* * rewriteRuleAction - * Rewrite the rule action with appropriate qualifiers (taken from * the triggering query). * * Input arguments: * parsetree - original query * rule_action - one action (query) of a rule * rule_qual - WHERE condition of rule, or NULL if unconditional * rt_index - RT index of result relation in original query * event - type of rule event * Output arguments: * *returning_flag - set true if we rewrite RETURNING clause in rule_action * (must be initialized to false) * Return value: * rewritten form of rule_action */ static Query * rewriteRuleAction(Query *parsetree, Query *rule_action, Node *rule_qual, int rt_index, CmdType event, bool *returning_flag) { int current_varno, new_varno; int rt_length; Query *sub_action; Query **sub_action_ptr; acquireLocksOnSubLinks_context context; ListCell *lc; context.for_execute = true; /* * Make modifiable copies of rule action and qual (what we're passed are * the stored versions in the relcache; don't touch 'em!). */ rule_action = copyObject(rule_action); rule_qual = copyObject(rule_qual); /* * Acquire necessary locks and fix any deleted JOIN RTE entries. */ AcquireRewriteLocks(rule_action, true, false); (void) acquireLocksOnSubLinks(rule_qual, &context); current_varno = rt_index; rt_length = list_length(parsetree->rtable); new_varno = PRS2_NEW_VARNO + rt_length; /* * Adjust rule action and qual to offset its varnos, so that we can merge * its rtable with the main parsetree's rtable. * * If the rule action is an INSERT...SELECT, the OLD/NEW rtable entries * will be in the SELECT part, and we have to modify that rather than the * top-level INSERT (kluge!). */ sub_action = getInsertSelectQuery(rule_action, &sub_action_ptr); OffsetVarNodes((Node *) sub_action, rt_length, 0); OffsetVarNodes(rule_qual, rt_length, 0); /* but references to OLD should point at original rt_index */ ChangeVarNodes((Node *) sub_action, PRS2_OLD_VARNO + rt_length, rt_index, 0); ChangeVarNodes(rule_qual, PRS2_OLD_VARNO + rt_length, rt_index, 0); /* * Mark any subquery RTEs in the rule action as LATERAL if they contain * Vars referring to the current query level (references to NEW/OLD). * Those really are lateral references, but we've historically not * required users to mark such subqueries with LATERAL explicitly. But * the planner will complain if such Vars exist in a non-LATERAL subquery, * so we have to fix things up here. */ foreach(lc, sub_action->rtable) { RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc); if (rte->rtekind == RTE_SUBQUERY && !rte->lateral && contain_vars_of_level((Node *) rte->subquery, 1)) rte->lateral = true; } /* * Generate expanded rtable consisting of main parsetree's rtable plus * rule action's rtable; this becomes the complete rtable for the rule * action. Some of the entries may be unused after we finish rewriting, * but we leave them all in place to avoid having to adjust the query's * varnos. RT entries that are not referenced in the completed jointree * will be ignored by the planner, so they do not affect query semantics. * * Also merge RTEPermissionInfo lists to ensure that all permissions are * checked correctly. * * If the rule is INSTEAD, then the original query won't be executed at * all, and so its rteperminfos must be preserved so that the executor * will do the correct permissions checks on the relations referenced in * it. This allows us to check that the caller has, say, insert-permission * on a view, when the view is not semantically referenced at all in the * resulting query. * * When a rule is not INSTEAD, the permissions checks done using the * copied entries will be redundant with those done during execution of * the original query, but we don't bother to treat that case differently. * * NOTE: because planner will destructively alter rtable and rteperminfos, * we must ensure that rule action's lists are separate and shares no * substructure with the main query's lists. Hence do a deep copy here * for both. */ { List *rtable_tail = sub_action->rtable; List *perminfos_tail = sub_action->rteperminfos; /* * RewriteQuery relies on the fact that RT entries from the original * query appear at the start of the expanded rtable, so we put the * action's original table at the end of the list. */ sub_action->rtable = copyObject(parsetree->rtable); sub_action->rteperminfos = copyObject(parsetree->rteperminfos); CombineRangeTables(&sub_action->rtable, &sub_action->rteperminfos, rtable_tail, perminfos_tail); } /* * There could have been some SubLinks in parsetree's rtable, in which * case we'd better mark the sub_action correctly. */ if (parsetree->hasSubLinks && !sub_action->hasSubLinks) { foreach(lc, parsetree->rtable) { RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc); switch (rte->rtekind) { case RTE_RELATION: sub_action->hasSubLinks = checkExprHasSubLink((Node *) rte->tablesample); break; case RTE_FUNCTION: sub_action->hasSubLinks = checkExprHasSubLink((Node *) rte->functions); break; case RTE_TABLEFUNC: sub_action->hasSubLinks = checkExprHasSubLink((Node *) rte->tablefunc); break; case RTE_VALUES: sub_action->hasSubLinks = checkExprHasSubLink((Node *) rte->values_lists); break; default: /* other RTE types don't contain bare expressions */ break; } sub_action->hasSubLinks |= checkExprHasSubLink((Node *) rte->securityQuals); if (sub_action->hasSubLinks) break; /* no need to keep scanning rtable */ } } /* * Also, we might have absorbed some RTEs with RLS conditions into the * sub_action. If so, mark it as hasRowSecurity, whether or not those * RTEs will be referenced after we finish rewriting. (Note: currently * this is a no-op because RLS conditions aren't added till later, but it * seems like good future-proofing to do this anyway.) */ sub_action->hasRowSecurity |= parsetree->hasRowSecurity; /* * Each rule action's jointree should be the main parsetree's jointree * plus that rule's jointree, but usually *without* the original rtindex * that we're replacing (if present, which it won't be for INSERT). Note * that if the rule action refers to OLD, its jointree will add a * reference to rt_index. If the rule action doesn't refer to OLD, but * either the rule_qual or the user query quals do, then we need to keep * the original rtindex in the jointree to provide data for the quals. We * don't want the original rtindex to be joined twice, however, so avoid * keeping it if the rule action mentions it. * * As above, the action's jointree must not share substructure with the * main parsetree's. */ if (sub_action->commandType != CMD_UTILITY) { bool keeporig; List *newjointree; Assert(sub_action->jointree != NULL); keeporig = (!rangeTableEntry_used((Node *) sub_action->jointree, rt_index, 0)) && (rangeTableEntry_used(rule_qual, rt_index, 0) || rangeTableEntry_used(parsetree->jointree->quals, rt_index, 0)); newjointree = adjustJoinTreeList(parsetree, !keeporig, rt_index); if (newjointree != NIL) { /* * If sub_action is a setop, manipulating its jointree will do no * good at all, because the jointree is dummy. (Perhaps someday * we could push the joining and quals down to the member * statements of the setop?) */ if (sub_action->setOperations != NULL) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented"))); sub_action->jointree->fromlist = list_concat(newjointree, sub_action->jointree->fromlist); /* * There could have been some SubLinks in newjointree, in which * case we'd better mark the sub_action correctly. */ if (parsetree->hasSubLinks && !sub_action->hasSubLinks) sub_action->hasSubLinks = checkExprHasSubLink((Node *) newjointree); } } /* * If the original query has any CTEs, copy them into the rule action. But * we don't need them for a utility action. */ if (parsetree->cteList != NIL && sub_action->commandType != CMD_UTILITY) { /* * Annoying implementation restriction: because CTEs are identified by * name within a cteList, we can't merge a CTE from the original query * if it has the same name as any CTE in the rule action. * * This could possibly be fixed by using some sort of internally * generated ID, instead of names, to link CTE RTEs to their CTEs. * However, decompiling the results would be quite confusing; note the * merge of hasRecursive flags below, which could change the apparent * semantics of such redundantly-named CTEs. */ foreach(lc, parsetree->cteList) { CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc); ListCell *lc2; foreach(lc2, sub_action->cteList) { CommonTableExpr *cte2 = (CommonTableExpr *) lfirst(lc2); if (strcmp(cte->ctename, cte2->ctename) == 0) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("WITH query name \"%s\" appears in both a rule action and the query being rewritten", cte->ctename))); } } /* OK, it's safe to combine the CTE lists */ sub_action->cteList = list_concat(sub_action->cteList, copyObject(parsetree->cteList)); /* ... and don't forget about the associated flags */ sub_action->hasRecursive |= parsetree->hasRecursive; sub_action->hasModifyingCTE |= parsetree->hasModifyingCTE; /* * If rule_action is different from sub_action (i.e., the rule action * is an INSERT...SELECT), then we might have just added some * data-modifying CTEs that are not at the top query level. This is * disallowed by the parser and we mustn't generate such trees here * either, so throw an error. * * Conceivably such cases could be supported by attaching the original * query's CTEs to rule_action not sub_action. But to do that, we'd * have to increment ctelevelsup in RTEs and SubLinks copied from the * original query. For now, it doesn't seem worth the trouble. */ if (sub_action->hasModifyingCTE && rule_action != sub_action) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("INSERT ... SELECT rule actions are not supported for queries having data-modifying statements in WITH"))); } /* * Event Qualification forces copying of parsetree and splitting into two * queries one w/rule_qual, one w/NOT rule_qual. Also add user query qual * onto rule action */ AddQual(sub_action, rule_qual); AddQual(sub_action, parsetree->jointree->quals); /* * Rewrite new.attribute with right hand side of target-list entry for * appropriate field name in insert/update. * * KLUGE ALERT: since ReplaceVarsFromTargetList returns a mutated copy, we * can't just apply it to sub_action; we have to remember to update the * sublink inside rule_action, too. */ if ((event == CMD_INSERT || event == CMD_UPDATE) && sub_action->commandType != CMD_UTILITY) { sub_action = (Query *) ReplaceVarsFromTargetList((Node *) sub_action, new_varno, 0, rt_fetch(new_varno, sub_action->rtable), parsetree->targetList, sub_action->resultRelation, (event == CMD_UPDATE) ? REPLACEVARS_CHANGE_VARNO : REPLACEVARS_SUBSTITUTE_NULL, current_varno, NULL); if (sub_action_ptr) *sub_action_ptr = sub_action; else rule_action = sub_action; } /* * If rule_action has a RETURNING clause, then either throw it away if the * triggering query has no RETURNING clause, or rewrite it to emit what * the triggering query's RETURNING clause asks for. Throw an error if * more than one rule has a RETURNING clause. */ if (!parsetree->returningList) rule_action->returningList = NIL; else if (rule_action->returningList) { if (*returning_flag) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot have RETURNING lists in multiple rules"))); *returning_flag = true; rule_action->returningList = (List *) ReplaceVarsFromTargetList((Node *) parsetree->returningList, parsetree->resultRelation, 0, rt_fetch(parsetree->resultRelation, parsetree->rtable), rule_action->returningList, rule_action->resultRelation, REPLACEVARS_REPORT_ERROR, 0, &rule_action->hasSubLinks); /* use triggering query's aliases for OLD and NEW in RETURNING list */ rule_action->returningOldAlias = parsetree->returningOldAlias; rule_action->returningNewAlias = parsetree->returningNewAlias; /* * There could have been some SubLinks in parsetree's returningList, * in which case we'd better mark the rule_action correctly. */ if (parsetree->hasSubLinks && !rule_action->hasSubLinks) rule_action->hasSubLinks = checkExprHasSubLink((Node *) rule_action->returningList); } return rule_action; } /* * Copy the query's jointree list, and optionally attempt to remove any * occurrence of the given rt_index as a top-level join item (we do not look * for it within join items; this is OK because we are only expecting to find * it as an UPDATE or DELETE target relation, which will be at the top level * of the join). Returns modified jointree list --- this is a separate copy * sharing no nodes with the original. */ static List * adjustJoinTreeList(Query *parsetree, bool removert, int rt_index) { List *newjointree = copyObject(parsetree->jointree->fromlist); ListCell *l; if (removert) { foreach(l, newjointree) { RangeTblRef *rtr = lfirst(l); if (IsA(rtr, RangeTblRef) && rtr->rtindex == rt_index) { newjointree = foreach_delete_current(newjointree, l); break; } } } return newjointree; } /* * rewriteTargetListIU - rewrite INSERT/UPDATE targetlist into standard form * * This has the following responsibilities: * * 1. For an INSERT, add tlist entries to compute default values for any * attributes that have defaults and are not assigned to in the given tlist. * (We do not insert anything for default-less attributes, however. The * planner will later insert NULLs for them, but there's no reason to slow * down rewriter processing with extra tlist nodes.) Also, for both INSERT * and UPDATE, replace explicit DEFAULT specifications with column default * expressions. * * 2. Merge multiple entries for the same target attribute, or declare error * if we can't. Multiple entries are only allowed for INSERT/UPDATE of * portions of an array or record field, for example * UPDATE table SET foo[2] = 42, foo[4] = 43; * We can merge such operations into a single assignment op. Essentially, * the expression we want to produce in this case is like * foo = array_set_element(array_set_element(foo, 2, 42), 4, 43) * * 3. Sort the tlist into standard order: non-junk fields in order by resno, * then junk fields (these in no particular order). * * We must do items 1 and 2 before firing rewrite rules, else rewritten * references to NEW.foo will produce wrong or incomplete results. Item 3 * is not needed for rewriting, but it is helpful for the planner, and we * can do it essentially for free while handling the other items. * * If values_rte is non-NULL (i.e., we are doing a multi-row INSERT using * values from a VALUES RTE), we populate *unused_values_attrnos with the * attribute numbers of any unused columns from the VALUES RTE. This can * happen for identity and generated columns whose targetlist entries are * replaced with generated expressions (if INSERT ... OVERRIDING USER VALUE is * used, or all the values to be inserted are DEFAULT). This information is * required by rewriteValuesRTE() to handle any DEFAULT items in the unused * columns. The caller must have initialized *unused_values_attrnos to NULL. */ static List * rewriteTargetListIU(List *targetList, CmdType commandType, OverridingKind override, Relation target_relation, RangeTblEntry *values_rte, int values_rte_index, Bitmapset **unused_values_attrnos) { TargetEntry **new_tles; List *new_tlist = NIL; List *junk_tlist = NIL; Form_pg_attribute att_tup; int attrno, next_junk_attrno, numattrs; ListCell *temp; Bitmapset *default_only_cols = NULL; /* * We process the normal (non-junk) attributes by scanning the input tlist * once and transferring TLEs into an array, then scanning the array to * build an output tlist. This avoids O(N^2) behavior for large numbers * of attributes. * * Junk attributes are tossed into a separate list during the same tlist * scan, then appended to the reconstructed tlist. */ numattrs = RelationGetNumberOfAttributes(target_relation); new_tles = (TargetEntry **) palloc0(numattrs * sizeof(TargetEntry *)); next_junk_attrno = numattrs + 1; foreach(temp, targetList) { TargetEntry *old_tle = (TargetEntry *) lfirst(temp); if (!old_tle->resjunk) { /* Normal attr: stash it into new_tles[] */ attrno = old_tle->resno; if (attrno < 1 || attrno > numattrs) elog(ERROR, "bogus resno %d in targetlist", attrno); att_tup = TupleDescAttr(target_relation->rd_att, attrno - 1); /* We can (and must) ignore deleted attributes */ if (att_tup->attisdropped) continue; /* Merge with any prior assignment to same attribute */ new_tles[attrno - 1] = process_matched_tle(old_tle, new_tles[attrno - 1], NameStr(att_tup->attname)); } else { /* * Copy all resjunk tlist entries to junk_tlist, and assign them * resnos above the last real resno. * * Typical junk entries include ORDER BY or GROUP BY expressions * (are these actually possible in an INSERT or UPDATE?), system * attribute references, etc. */ /* Get the resno right, but don't copy unnecessarily */ if (old_tle->resno != next_junk_attrno) { old_tle = flatCopyTargetEntry(old_tle); old_tle->resno = next_junk_attrno; } junk_tlist = lappend(junk_tlist, old_tle); next_junk_attrno++; } } for (attrno = 1; attrno <= numattrs; attrno++) { TargetEntry *new_tle = new_tles[attrno - 1]; bool apply_default; att_tup = TupleDescAttr(target_relation->rd_att, attrno - 1); /* We can (and must) ignore deleted attributes */ if (att_tup->attisdropped) continue; /* * Handle the two cases where we need to insert a default expression: * it's an INSERT and there's no tlist entry for the column, or the * tlist entry is a DEFAULT placeholder node. */ apply_default = ((new_tle == NULL && commandType == CMD_INSERT) || (new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault))); if (commandType == CMD_INSERT) { int values_attrno = 0; /* Source attribute number for values that come from a VALUES RTE */ if (values_rte && new_tle && IsA(new_tle->expr, Var)) { Var *var = (Var *) new_tle->expr; if (var->varno == values_rte_index) values_attrno = var->varattno; } /* * Can only insert DEFAULT into GENERATED ALWAYS identity columns, * unless either OVERRIDING USER VALUE or OVERRIDING SYSTEM VALUE * is specified. */ if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && !apply_default) { if (override == OVERRIDING_USER_VALUE) apply_default = true; else if (override != OVERRIDING_SYSTEM_VALUE) { /* * If this column's values come from a VALUES RTE, test * whether it contains only SetToDefault items. Since the * VALUES list might be quite large, we arrange to only * scan it once. */ if (values_attrno != 0) { if (default_only_cols == NULL) default_only_cols = findDefaultOnlyColumns(values_rte); if (bms_is_member(values_attrno, default_only_cols)) apply_default = true; } if (!apply_default) ereport(ERROR, (errcode(ERRCODE_GENERATED_ALWAYS), errmsg("cannot insert a non-DEFAULT value into column \"%s\"", NameStr(att_tup->attname)), errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.", NameStr(att_tup->attname)), errhint("Use OVERRIDING SYSTEM VALUE to override."))); } } /* * Although inserting into a GENERATED BY DEFAULT identity column * is allowed, apply the default if OVERRIDING USER VALUE is * specified. */ if (att_tup->attidentity == ATTRIBUTE_IDENTITY_BY_DEFAULT && override == OVERRIDING_USER_VALUE) apply_default = true; /* * Can only insert DEFAULT into generated columns, regardless of * any OVERRIDING clauses. */ if (att_tup->attgenerated && !apply_default) { /* * If this column's values come from a VALUES RTE, test * whether it contains only SetToDefault items, as above. */ if (values_attrno != 0) { if (default_only_cols == NULL) default_only_cols = findDefaultOnlyColumns(values_rte); if (bms_is_member(values_attrno, default_only_cols)) apply_default = true; } if (!apply_default) ereport(ERROR, (errcode(ERRCODE_GENERATED_ALWAYS), errmsg("cannot insert a non-DEFAULT value into column \"%s\"", NameStr(att_tup->attname)), errdetail("Column \"%s\" is a generated column.", NameStr(att_tup->attname)))); } /* * For an INSERT from a VALUES RTE, return the attribute numbers * of any VALUES columns that will no longer be used (due to the * targetlist entry being replaced by a default expression). */ if (values_attrno != 0 && apply_default && unused_values_attrnos) *unused_values_attrnos = bms_add_member(*unused_values_attrnos, values_attrno); } /* * Updates to identity and generated columns follow the same rules as * above, except that UPDATE doesn't admit OVERRIDING clauses. Also, * the source can't be a VALUES RTE, so we needn't consider that. */ if (commandType == CMD_UPDATE) { if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && new_tle && !apply_default) ereport(ERROR, (errcode(ERRCODE_GENERATED_ALWAYS), errmsg("column \"%s\" can only be updated to DEFAULT", NameStr(att_tup->attname)), errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.", NameStr(att_tup->attname)))); if (att_tup->attgenerated && new_tle && !apply_default) ereport(ERROR, (errcode(ERRCODE_GENERATED_ALWAYS), errmsg("column \"%s\" can only be updated to DEFAULT", NameStr(att_tup->attname)), errdetail("Column \"%s\" is a generated column.", NameStr(att_tup->attname)))); } if (att_tup->attgenerated) { /* * virtual generated column stores a null value; stored generated * column will be fixed in executor */ new_tle = NULL; } else if (apply_default) { Node *new_expr; new_expr = build_column_default(target_relation, attrno); /* * If there is no default (ie, default is effectively NULL), we * can omit the tlist entry in the INSERT case, since the planner * can insert a NULL for itself, and there's no point in spending * any more rewriter cycles on the entry. But in the UPDATE case * we've got to explicitly set the column to NULL. */ if (!new_expr) { if (commandType == CMD_INSERT) new_tle = NULL; else new_expr = coerce_null_to_domain(att_tup->atttypid, att_tup->atttypmod, att_tup->attcollation, att_tup->attlen, att_tup->attbyval); } if (new_expr) new_tle = makeTargetEntry((Expr *) new_expr, attrno, pstrdup(NameStr(att_tup->attname)), false); } if (new_tle) new_tlist = lappend(new_tlist, new_tle); } pfree(new_tles); return list_concat(new_tlist, junk_tlist); } /* * Convert a matched TLE from the original tlist into a correct new TLE. * * This routine detects and handles multiple assignments to the same target * attribute. (The attribute name is needed only for error messages.) */ static TargetEntry * process_matched_tle(TargetEntry *src_tle, TargetEntry *prior_tle, const char *attrName) { TargetEntry *result; CoerceToDomain *coerce_expr = NULL; Node *src_expr; Node *prior_expr; Node *src_input; Node *prior_input; Node *priorbottom; Node *newexpr; if (prior_tle == NULL) { /* * Normal case where this is the first assignment to the attribute. */ return src_tle; } /*---------- * Multiple assignments to same attribute. Allow only if all are * FieldStore or SubscriptingRef assignment operations. This is a bit * tricky because what we may actually be looking at is a nest of * such nodes; consider * UPDATE tab SET col.fld1.subfld1 = x, col.fld2.subfld2 = y * The two expressions produced by the parser will look like * FieldStore(col, fld1, FieldStore(placeholder, subfld1, x)) * FieldStore(col, fld2, FieldStore(placeholder, subfld2, y)) * However, we can ignore the substructure and just consider the top * FieldStore or SubscriptingRef from each assignment, because it works to * combine these as * FieldStore(FieldStore(col, fld1, * FieldStore(placeholder, subfld1, x)), * fld2, FieldStore(placeholder, subfld2, y)) * Note the leftmost expression goes on the inside so that the * assignments appear to occur left-to-right. * * For FieldStore, instead of nesting we can generate a single * FieldStore with multiple target fields. We must nest when * SubscriptingRefs are involved though. * * As a further complication, the destination column might be a domain, * resulting in each assignment containing a CoerceToDomain node over a * FieldStore or SubscriptingRef. These should have matching target * domains, so we strip them and reconstitute a single CoerceToDomain over * the combined FieldStore/SubscriptingRef nodes. (Notice that this has * the result that the domain's checks are applied only after we do all * the field or element updates, not after each one. This is desirable.) *---------- */ src_expr = (Node *) src_tle->expr; prior_expr = (Node *) prior_tle->expr; if (src_expr && IsA(src_expr, CoerceToDomain) && prior_expr && IsA(prior_expr, CoerceToDomain) && ((CoerceToDomain *) src_expr)->resulttype == ((CoerceToDomain *) prior_expr)->resulttype) { /* we assume without checking that resulttypmod/resultcollid match */ coerce_expr = (CoerceToDomain *) src_expr; src_expr = (Node *) ((CoerceToDomain *) src_expr)->arg; prior_expr = (Node *) ((CoerceToDomain *) prior_expr)->arg; } src_input = get_assignment_input(src_expr); prior_input = get_assignment_input(prior_expr); if (src_input == NULL || prior_input == NULL || exprType(src_expr) != exprType(prior_expr)) ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR), errmsg("multiple assignments to same column \"%s\"", attrName))); /* * Prior TLE could be a nest of assignments if we do this more than once. */ priorbottom = prior_input; for (;;) { Node *newbottom = get_assignment_input(priorbottom); if (newbottom == NULL) break; /* found the original Var reference */ priorbottom = newbottom; } if (!equal(priorbottom, src_input)) ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR), errmsg("multiple assignments to same column \"%s\"", attrName))); /* * Looks OK to nest 'em. */ if (IsA(src_expr, FieldStore)) { FieldStore *fstore = makeNode(FieldStore); if (IsA(prior_expr, FieldStore)) { /* combine the two */ memcpy(fstore, prior_expr, sizeof(FieldStore)); fstore->newvals = list_concat_copy(((FieldStore *) prior_expr)->newvals, ((FieldStore *) src_expr)->newvals); fstore->fieldnums = list_concat_copy(((FieldStore *) prior_expr)->fieldnums, ((FieldStore *) src_expr)->fieldnums); } else { /* general case, just nest 'em */ memcpy(fstore, src_expr, sizeof(FieldStore)); fstore->arg = (Expr *) prior_expr; } newexpr = (Node *) fstore; } else if (IsA(src_expr, SubscriptingRef)) { SubscriptingRef *sbsref = makeNode(SubscriptingRef); memcpy(sbsref, src_expr, sizeof(SubscriptingRef)); sbsref->refexpr = (Expr *) prior_expr; newexpr = (Node *) sbsref; } else { elog(ERROR, "cannot happen"); newexpr = NULL; } if (coerce_expr) { /* put back the CoerceToDomain */ CoerceToDomain *newcoerce = makeNode(CoerceToDomain); memcpy(newcoerce, coerce_expr, sizeof(CoerceToDomain)); newcoerce->arg = (Expr *) newexpr; newexpr = (Node *) newcoerce; } result = flatCopyTargetEntry(src_tle); result->expr = (Expr *) newexpr; return result; } /* * If node is an assignment node, return its input; else return NULL */ static Node * get_assignment_input(Node *node) { if (node == NULL) return NULL; if (IsA(node, FieldStore)) { FieldStore *fstore = (FieldStore *) node; return (Node *) fstore->arg; } else if (IsA(node, SubscriptingRef)) { SubscriptingRef *sbsref = (SubscriptingRef *) node; if (sbsref->refassgnexpr == NULL) return NULL; return (Node *) sbsref->refexpr; } return NULL; } /* * Make an expression tree for the default value for a column. * * If there is no default, return a NULL instead. */ Node * build_column_default(Relation rel, int attrno) { TupleDesc rd_att = rel->rd_att; Form_pg_attribute att_tup = TupleDescAttr(rd_att, attrno - 1); Oid atttype = att_tup->atttypid; int32 atttypmod = att_tup->atttypmod; Node *expr = NULL; Oid exprtype; if (att_tup->attidentity) { NextValueExpr *nve = makeNode(NextValueExpr); nve->seqid = getIdentitySequence(rel, attrno, false); nve->typeId = att_tup->atttypid; return (Node *) nve; } /* * If relation has a default for this column, fetch that expression. */ if (att_tup->atthasdef) { expr = TupleDescGetDefault(rd_att, attrno); if (expr == NULL) elog(ERROR, "default expression not found for attribute %d of relation \"%s\"", attrno, RelationGetRelationName(rel)); } /* * No per-column default, so look for a default for the type itself. But * not for generated columns. */ if (expr == NULL && !att_tup->attgenerated) expr = get_typdefault(atttype); if (expr == NULL) return NULL; /* No default anywhere */ /* * Make sure the value is coerced to the target column type; this will * generally be true already, but there seem to be some corner cases * involving domain defaults where it might not be true. This should match * the parser's processing of non-defaulted expressions --- see * transformAssignedExpr(). */ exprtype = exprType(expr); expr = coerce_to_target_type(NULL, /* no UNKNOWN params here */ expr, exprtype, atttype, atttypmod, COERCION_ASSIGNMENT, COERCE_IMPLICIT_CAST, -1); if (expr == NULL) ereport(ERROR, (errcode(ERRCODE_DATATYPE_MISMATCH), errmsg("column \"%s\" is of type %s" " but default expression is of type %s", NameStr(att_tup->attname), format_type_be(atttype), format_type_be(exprtype)), errhint("You will need to rewrite or cast the expression."))); return expr; } /* Does VALUES RTE contain any SetToDefault items? */ static bool searchForDefault(RangeTblEntry *rte) { ListCell *lc; foreach(lc, rte->values_lists) { List *sublist = (List *) lfirst(lc); ListCell *lc2; foreach(lc2, sublist) { Node *col = (Node *) lfirst(lc2); if (IsA(col, SetToDefault)) return true; } } return false; } /* * Search a VALUES RTE for columns that contain only SetToDefault items, * returning a Bitmapset containing the attribute numbers of any such columns. */ static Bitmapset * findDefaultOnlyColumns(RangeTblEntry *rte) { Bitmapset *default_only_cols = NULL; ListCell *lc; foreach(lc, rte->values_lists) { List *sublist = (List *) lfirst(lc); ListCell *lc2; int i; if (default_only_cols == NULL) { /* Populate the initial result bitmap from the first row */ i = 0; foreach(lc2, sublist) { Node *col = (Node *) lfirst(lc2); i++; if (IsA(col, SetToDefault)) default_only_cols = bms_add_member(default_only_cols, i); } } else { /* Update the result bitmap from this next row */ i = 0; foreach(lc2, sublist) { Node *col = (Node *) lfirst(lc2); i++; if (!IsA(col, SetToDefault)) default_only_cols = bms_del_member(default_only_cols, i); } } /* * If no column in the rows read so far contains only DEFAULT items, * we are done. */ if (bms_is_empty(default_only_cols)) break; } return default_only_cols; } /* * When processing INSERT ... VALUES with a VALUES RTE (ie, multiple VALUES * lists), we have to replace any DEFAULT items in the VALUES lists with * the appropriate default expressions. The other aspects of targetlist * rewriting need be applied only to the query's targetlist proper. * * For an auto-updatable view, each DEFAULT item in the VALUES list is * replaced with the default from the view, if it has one. Otherwise it is * left untouched so that the underlying base relation's default can be * applied instead (when we later recurse to here after rewriting the query * to refer to the base relation instead of the view). * * For other types of relation, including rule- and trigger-updatable views, * all DEFAULT items are replaced, and if the target relation doesn't have a * default, the value is explicitly set to NULL. * * Also, if a DEFAULT item is found in a column mentioned in unused_cols, * it is explicitly set to NULL. This happens for columns in the VALUES RTE * whose corresponding targetlist entries have already been replaced with the * relation's default expressions, so that any values in those columns of the * VALUES RTE are no longer used. This can happen for identity and generated * columns (if INSERT ... OVERRIDING USER VALUE is used, or all the values to * be inserted are DEFAULT). In principle we could replace all entries in * such a column with NULL, whether DEFAULT or not; but it doesn't seem worth * the trouble. * * Note that we may have subscripted or field assignment targetlist entries, * as well as more complex expressions from already-replaced DEFAULT items if * we have recursed to here for an auto-updatable view. However, it ought to * be impossible for such entries to have DEFAULTs assigned to them, except * for unused columns, as described above --- we should only have to replace * DEFAULT items for targetlist entries that contain simple Vars referencing * the VALUES RTE, or which are no longer referred to by the targetlist. * * Returns true if all DEFAULT items were replaced, and false if some were * left untouched. */ static bool rewriteValuesRTE(Query *parsetree, RangeTblEntry *rte, int rti, Relation target_relation, Bitmapset *unused_cols) { List *newValues; ListCell *lc; bool isAutoUpdatableView; bool allReplaced; int numattrs; int *attrnos; /* Steps below are not sensible for non-INSERT queries */ Assert(parsetree->commandType == CMD_INSERT); Assert(rte->rtekind == RTE_VALUES); /* * Rebuilding all the lists is a pretty expensive proposition in a big * VALUES list, and it's a waste of time if there aren't any DEFAULT * placeholders. So first scan to see if there are any. */ if (!searchForDefault(rte)) return true; /* nothing to do */ /* * Scan the targetlist for entries referring to the VALUES RTE, and note * the target attributes. As noted above, we should only need to do this * for targetlist entries containing simple Vars --- nothing else in the * VALUES RTE should contain DEFAULT items (except possibly for unused * columns), and we complain if such a thing does occur. */ numattrs = list_length(linitial(rte->values_lists)); attrnos = (int *) palloc0(numattrs * sizeof(int)); foreach(lc, parsetree->targetList) { TargetEntry *tle = (TargetEntry *) lfirst(lc); if (IsA(tle->expr, Var)) { Var *var = (Var *) tle->expr; if (var->varno == rti) { int attrno = var->varattno; Assert(attrno >= 1 && attrno <= numattrs); attrnos[attrno - 1] = tle->resno; } } } /* * Check if the target relation is an auto-updatable view, in which case * unresolved defaults will be left untouched rather than being set to * NULL. */ isAutoUpdatableView = false; if (target_relation->rd_rel->relkind == RELKIND_VIEW && !view_has_instead_trigger(target_relation, CMD_INSERT, NIL)) { List *locks; bool hasUpdate; bool found; ListCell *l; /* Look for an unconditional DO INSTEAD rule */ locks = matchLocks(CMD_INSERT, target_relation, parsetree->resultRelation, parsetree, &hasUpdate); found = false; foreach(l, locks) { RewriteRule *rule_lock = (RewriteRule *) lfirst(l); if (rule_lock->isInstead && rule_lock->qual == NULL) { found = true; break; } } /* * If we didn't find an unconditional DO INSTEAD rule, assume that the * view is auto-updatable. If it isn't, rewriteTargetView() will * throw an error. */ if (!found) isAutoUpdatableView = true; } newValues = NIL; allReplaced = true; foreach(lc, rte->values_lists) { List *sublist = (List *) lfirst(lc); List *newList = NIL; ListCell *lc2; int i; Assert(list_length(sublist) == numattrs); i = 0; foreach(lc2, sublist) { Node *col = (Node *) lfirst(lc2); int attrno = attrnos[i++]; if (IsA(col, SetToDefault)) { Form_pg_attribute att_tup; Node *new_expr; /* * If this column isn't used, just replace the DEFAULT with * NULL (attrno will be 0 in this case because the targetlist * entry will have been replaced by the default expression). */ if (bms_is_member(i, unused_cols)) { SetToDefault *def = (SetToDefault *) col; newList = lappend(newList, makeNullConst(def->typeId, def->typeMod, def->collation)); continue; } if (attrno == 0) elog(ERROR, "cannot set value in column %d to DEFAULT", i); Assert(attrno > 0 && attrno <= target_relation->rd_att->natts); att_tup = TupleDescAttr(target_relation->rd_att, attrno - 1); if (!att_tup->attisdropped) new_expr = build_column_default(target_relation, attrno); else new_expr = NULL; /* force a NULL if dropped */ /* * If there is no default (ie, default is effectively NULL), * we've got to explicitly set the column to NULL, unless the * target relation is an auto-updatable view. */ if (!new_expr) { if (isAutoUpdatableView) { /* Leave the value untouched */ newList = lappend(newList, col); allReplaced = false; continue; } new_expr = coerce_null_to_domain(att_tup->atttypid, att_tup->atttypmod, att_tup->attcollation, att_tup->attlen, att_tup->attbyval); } newList = lappend(newList, new_expr); } else newList = lappend(newList, col); } newValues = lappend(newValues, newList); } rte->values_lists = newValues; pfree(attrnos); return allReplaced; } /* * Mop up any remaining DEFAULT items in the given VALUES RTE by * replacing them with NULL constants. * * This is used for the product queries generated by DO ALSO rules attached to * an auto-updatable view. The action can't depend on the "target relation" * since the product query might not have one (it needn't be an INSERT). * Essentially, such queries are treated as being attached to a rule-updatable * view. */ static void rewriteValuesRTEToNulls(Query *parsetree, RangeTblEntry *rte) { List *newValues; ListCell *lc; newValues = NIL; foreach(lc, rte->values_lists) { List *sublist = (List *) lfirst(lc); List *newList = NIL; ListCell *lc2; foreach(lc2, sublist) { Node *col = (Node *) lfirst(lc2); if (IsA(col, SetToDefault)) { SetToDefault *def = (SetToDefault *) col; newList = lappend(newList, makeNullConst(def->typeId, def->typeMod, def->collation)); } else newList = lappend(newList, col); } newValues = lappend(newValues, newList); } rte->values_lists = newValues; } /* * matchLocks - * match a relation's list of locks and returns the matching rules */ static List * matchLocks(CmdType event, Relation relation, int varno, Query *parsetree, bool *hasUpdate) { RuleLock *rulelocks = relation->rd_rules; List *matching_locks = NIL; int nlocks; int i; if (rulelocks == NULL) return NIL; if (parsetree->commandType != CMD_SELECT) { if (parsetree->resultRelation != varno) return NIL; } nlocks = rulelocks->numLocks; for (i = 0; i < nlocks; i++) { RewriteRule *oneLock = rulelocks->rules[i]; if (oneLock->event == CMD_UPDATE) *hasUpdate = true; /* * Suppress ON INSERT/UPDATE/DELETE rules that are disabled or * configured to not fire during the current session's replication * role. ON SELECT rules will always be applied in order to keep views * working even in LOCAL or REPLICA role. */ if (oneLock->event != CMD_SELECT) { if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA) { if (oneLock->enabled == RULE_FIRES_ON_ORIGIN || oneLock->enabled == RULE_DISABLED) continue; } else /* ORIGIN or LOCAL ROLE */ { if (oneLock->enabled == RULE_FIRES_ON_REPLICA || oneLock->enabled == RULE_DISABLED) continue; } /* Non-SELECT rules are not supported for MERGE */ if (parsetree->commandType == CMD_MERGE) ereport(ERROR, errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot execute MERGE on relation \"%s\"", RelationGetRelationName(relation)), errdetail("MERGE is not supported for relations with rules.")); } if (oneLock->event == event) { if (parsetree->commandType != CMD_SELECT || rangeTableEntry_used((Node *) parsetree, varno, 0)) matching_locks = lappend(matching_locks, oneLock); } } return matching_locks; } /* * ApplyRetrieveRule - expand an ON SELECT rule */ static Query * ApplyRetrieveRule(Query *parsetree, RewriteRule *rule, int rt_index, Relation relation, List *activeRIRs) { Query *rule_action; RangeTblEntry *rte; RowMarkClause *rc; int numCols; if (list_length(rule->actions) != 1) elog(ERROR, "expected just one rule action"); if (rule->qual != NULL) elog(ERROR, "cannot handle qualified ON SELECT rule"); /* Check if the expansion of non-system views are restricted */ if (unlikely((restrict_nonsystem_relation_kind & RESTRICT_RELKIND_VIEW) != 0 && RelationGetRelid(relation) >= FirstNormalObjectId)) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("access to non-system view \"%s\" is restricted", RelationGetRelationName(relation)))); if (rt_index == parsetree->resultRelation) { /* * We have a view as the result relation of the query, and it wasn't * rewritten by any rule. This case is supported if there is an * INSTEAD OF trigger that will trap attempts to insert/update/delete * view rows. The executor will check that; for the moment just plow * ahead. We have two cases: * * For INSERT, we needn't do anything. The unmodified RTE will serve * fine as the result relation. * * For UPDATE/DELETE/MERGE, we need to expand the view so as to have * source data for the operation. But we also need an unmodified RTE * to serve as the target. So, copy the RTE and add the copy to the * rangetable. Note that the copy does not get added to the jointree. * Also note that there's a hack in fireRIRrules to avoid calling this * function again when it arrives at the copied RTE. */ if (parsetree->commandType == CMD_INSERT) return parsetree; else if (parsetree->commandType == CMD_UPDATE || parsetree->commandType == CMD_DELETE || parsetree->commandType == CMD_MERGE) { RangeTblEntry *newrte; Var *var; TargetEntry *tle; rte = rt_fetch(rt_index, parsetree->rtable); newrte = copyObject(rte); parsetree->rtable = lappend(parsetree->rtable, newrte); parsetree->resultRelation = list_length(parsetree->rtable); /* parsetree->mergeTargetRelation unchanged (use expanded view) */ /* * For the most part, Vars referencing the view should remain as * they are, meaning that they implicitly represent OLD values. * But in the RETURNING list if any, we want such Vars to * represent NEW values, so change them to reference the new RTE. * * Since ChangeVarNodes scribbles on the tree in-place, copy the * RETURNING list first for safety. */ parsetree->returningList = copyObject(parsetree->returningList); ChangeVarNodes((Node *) parsetree->returningList, rt_index, parsetree->resultRelation, 0); /* * To allow the executor to compute the original view row to pass * to the INSTEAD OF trigger, we add a resjunk whole-row Var * referencing the original RTE. This will later get expanded * into a RowExpr computing all the OLD values of the view row. */ var = makeWholeRowVar(rte, rt_index, 0, false); tle = makeTargetEntry((Expr *) var, list_length(parsetree->targetList) + 1, pstrdup("wholerow"), true); parsetree->targetList = lappend(parsetree->targetList, tle); /* Now, continue with expanding the original view RTE */ } else elog(ERROR, "unrecognized commandType: %d", (int) parsetree->commandType); } /* * Check if there's a FOR [KEY] UPDATE/SHARE clause applying to this view. * * Note: we needn't explicitly consider any such clauses appearing in * ancestor query levels; their effects have already been pushed down to * here by markQueryForLocking, and will be reflected in "rc". */ rc = get_parse_rowmark(parsetree, rt_index); /* * Make a modifiable copy of the view query, and acquire needed locks on * the relations it mentions. Force at least RowShareLock for all such * rels if there's a FOR [KEY] UPDATE/SHARE clause affecting this view. */ rule_action = copyObject(linitial(rule->actions)); AcquireRewriteLocks(rule_action, true, (rc != NULL)); /* * If FOR [KEY] UPDATE/SHARE of view, mark all the contained tables as * implicit FOR [KEY] UPDATE/SHARE, the same as the parser would have done * if the view's subquery had been written out explicitly. */ if (rc != NULL) markQueryForLocking(rule_action, (Node *) rule_action->jointree, rc->strength, rc->waitPolicy, true); /* * Recursively expand any view references inside the view. */ rule_action = fireRIRrules(rule_action, activeRIRs); /* * Make sure the query is marked as having row security if the view query * does. */ parsetree->hasRowSecurity |= rule_action->hasRowSecurity; /* * Now, plug the view query in as a subselect, converting the relation's * original RTE to a subquery RTE. */ rte = rt_fetch(rt_index, parsetree->rtable); rte->rtekind = RTE_SUBQUERY; rte->subquery = rule_action; rte->security_barrier = RelationIsSecurityView(relation); /* * Clear fields that should not be set in a subquery RTE. Note that we * leave the relid, relkind, rellockmode, and perminfoindex fields set, so * that the view relation can be appropriately locked before execution and * its permissions checked. */ rte->tablesample = NULL; rte->inh = false; /* must not be set for a subquery */ /* * Since we allow CREATE OR REPLACE VIEW to add columns to a view, the * rule_action might emit more columns than we expected when the current * query was parsed. Various places expect rte->eref->colnames to be * consistent with the non-junk output columns of the subquery, so patch * things up if necessary by adding some dummy column names. */ numCols = ExecCleanTargetListLength(rule_action->targetList); while (list_length(rte->eref->colnames) < numCols) { rte->eref->colnames = lappend(rte->eref->colnames, makeString(pstrdup("?column?"))); } return parsetree; } /* * Recursively mark all relations used by a view as FOR [KEY] UPDATE/SHARE. * * This may generate an invalid query, eg if some sub-query uses an * aggregate. We leave it to the planner to detect that. * * NB: this must agree with the parser's transformLockingClause() routine. * However, we used to have to avoid marking a view's OLD and NEW rels for * updating, which motivated scanning the jointree to determine which rels * are used. Possibly that could now be simplified into just scanning the * rangetable as the parser does. */ static void markQueryForLocking(Query *qry, Node *jtnode, LockClauseStrength strength, LockWaitPolicy waitPolicy, bool pushedDown) { if (jtnode == NULL) return; if (IsA(jtnode, RangeTblRef)) { int rti = ((RangeTblRef *) jtnode)->rtindex; RangeTblEntry *rte = rt_fetch(rti, qry->rtable); if (rte->rtekind == RTE_RELATION) { RTEPermissionInfo *perminfo; applyLockingClause(qry, rti, strength, waitPolicy, pushedDown); perminfo = getRTEPermissionInfo(qry->rteperminfos, rte); perminfo->requiredPerms |= ACL_SELECT_FOR_UPDATE; } else if (rte->rtekind == RTE_SUBQUERY) { applyLockingClause(qry, rti, strength, waitPolicy, pushedDown); /* FOR UPDATE/SHARE of subquery is propagated to subquery's rels */ markQueryForLocking(rte->subquery, (Node *) rte->subquery->jointree, strength, waitPolicy, true); } /* other RTE types are unaffected by FOR UPDATE */ } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; foreach(l, f->fromlist) markQueryForLocking(qry, lfirst(l), strength, waitPolicy, pushedDown); } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; markQueryForLocking(qry, j->larg, strength, waitPolicy, pushedDown); markQueryForLocking(qry, j->rarg, strength, waitPolicy, pushedDown); } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); } /* * fireRIRonSubLink - * Apply fireRIRrules() to each SubLink (subselect in expression) found * in the given tree. * * NOTE: although this has the form of a walker, we cheat and modify the * SubLink nodes in-place. It is caller's responsibility to ensure that * no unwanted side-effects occur! * * This is unlike most of the other routines that recurse into subselects, * because we must take control at the SubLink node in order to replace * the SubLink's subselect link with the possibly-rewritten subquery. */ static bool fireRIRonSubLink(Node *node, fireRIRonSubLink_context *context) { if (node == NULL) return false; if (IsA(node, SubLink)) { SubLink *sub = (SubLink *) node; /* Do what we came for */ sub->subselect = (Node *) fireRIRrules((Query *) sub->subselect, context->activeRIRs); /* * Remember if any of the sublinks have row security. */ context->hasRowSecurity |= ((Query *) sub->subselect)->hasRowSecurity; /* Fall through to process lefthand args of SubLink */ } /* * Do NOT recurse into Query nodes, because fireRIRrules already processed * subselects of subselects for us. */ return expression_tree_walker(node, fireRIRonSubLink, context); } /* * fireRIRrules - * Apply all RIR rules on each rangetable entry in the given query * * activeRIRs is a list of the OIDs of views we're already processing RIR * rules for, used to detect/reject recursion. */ static Query * fireRIRrules(Query *parsetree, List *activeRIRs) { int origResultRelation = parsetree->resultRelation; int rt_index; ListCell *lc; /* * Expand SEARCH and CYCLE clauses in CTEs. * * This is just a convenient place to do this, since we are already * looking at each Query. */ foreach(lc, parsetree->cteList) { CommonTableExpr *cte = lfirst_node(CommonTableExpr, lc); if (cte->search_clause || cte->cycle_clause) { cte = rewriteSearchAndCycle(cte); lfirst(lc) = cte; } } /* * don't try to convert this into a foreach loop, because rtable list can * get changed each time through... */ rt_index = 0; while (rt_index < list_length(parsetree->rtable)) { RangeTblEntry *rte; Relation rel; List *locks; RuleLock *rules; RewriteRule *rule; int i; ++rt_index; rte = rt_fetch(rt_index, parsetree->rtable); /* * A subquery RTE can't have associated rules, so there's nothing to * do to this level of the query, but we must recurse into the * subquery to expand any rule references in it. */ if (rte->rtekind == RTE_SUBQUERY) { rte->subquery = fireRIRrules(rte->subquery, activeRIRs); /* * While we are here, make sure the query is marked as having row * security if any of its subqueries do. */ parsetree->hasRowSecurity |= rte->subquery->hasRowSecurity; continue; } /* * Joins and other non-relation RTEs can be ignored completely. */ if (rte->rtekind != RTE_RELATION) continue; /* * Always ignore RIR rules for materialized views referenced in * queries. (This does not prevent refreshing MVs, since they aren't * referenced in their own query definitions.) * * Note: in the future we might want to allow MVs to be conditionally * expanded as if they were regular views, if they are not scannable. * In that case this test would need to be postponed till after we've * opened the rel, so that we could check its state. */ if (rte->relkind == RELKIND_MATVIEW) continue; /* * In INSERT ... ON CONFLICT, ignore the EXCLUDED pseudo-relation; * even if it points to a view, we needn't expand it, and should not * because we want the RTE to remain of RTE_RELATION type. Otherwise, * it would get changed to RTE_SUBQUERY type, which is an * untested/unsupported situation. */ if (parsetree->onConflict && rt_index == parsetree->onConflict->exclRelIndex) continue; /* * If the table is not referenced in the query, then we ignore it. * This prevents infinite expansion loop due to new rtable entries * inserted by expansion of a rule. A table is referenced if it is * part of the join set (a source table), or is referenced by any Var * nodes, or is the result table. */ if (rt_index != parsetree->resultRelation && !rangeTableEntry_used((Node *) parsetree, rt_index, 0)) continue; /* * Also, if this is a new result relation introduced by * ApplyRetrieveRule, we don't want to do anything more with it. */ if (rt_index == parsetree->resultRelation && rt_index != origResultRelation) continue; /* * We can use NoLock here since either the parser or * AcquireRewriteLocks should have locked the rel already. */ rel = table_open(rte->relid, NoLock); /* * Collect the RIR rules that we must apply */ rules = rel->rd_rules; if (rules != NULL) { locks = NIL; for (i = 0; i < rules->numLocks; i++) { rule = rules->rules[i]; if (rule->event != CMD_SELECT) continue; locks = lappend(locks, rule); } /* * If we found any, apply them --- but first check for recursion! */ if (locks != NIL) { ListCell *l; if (list_member_oid(activeRIRs, RelationGetRelid(rel))) ereport(ERROR, (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), errmsg("infinite recursion detected in rules for relation \"%s\"", RelationGetRelationName(rel)))); activeRIRs = lappend_oid(activeRIRs, RelationGetRelid(rel)); foreach(l, locks) { rule = lfirst(l); parsetree = ApplyRetrieveRule(parsetree, rule, rt_index, rel, activeRIRs); } activeRIRs = list_delete_last(activeRIRs); } } table_close(rel, NoLock); } /* Recurse into subqueries in WITH */ foreach(lc, parsetree->cteList) { CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc); cte->ctequery = (Node *) fireRIRrules((Query *) cte->ctequery, activeRIRs); /* * While we are here, make sure the query is marked as having row * security if any of its CTEs do. */ parsetree->hasRowSecurity |= ((Query *) cte->ctequery)->hasRowSecurity; } /* * Recurse into sublink subqueries, too. But we already did the ones in * the rtable and cteList. */ if (parsetree->hasSubLinks) { fireRIRonSubLink_context context; context.activeRIRs = activeRIRs; context.hasRowSecurity = false; query_tree_walker(parsetree, fireRIRonSubLink, &context, QTW_IGNORE_RC_SUBQUERIES); /* * Make sure the query is marked as having row security if any of its * sublinks do. */ parsetree->hasRowSecurity |= context.hasRowSecurity; } /* * Apply any row-level security policies. We do this last because it * requires special recursion detection if the new quals have sublink * subqueries, and if we did it in the loop above query_tree_walker would * then recurse into those quals a second time. */ rt_index = 0; foreach(lc, parsetree->rtable) { RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc); Relation rel; List *securityQuals; List *withCheckOptions; bool hasRowSecurity; bool hasSubLinks; ++rt_index; /* Only normal relations can have RLS policies */ if (rte->rtekind != RTE_RELATION || (rte->relkind != RELKIND_RELATION && rte->relkind != RELKIND_PARTITIONED_TABLE)) continue; rel = table_open(rte->relid, NoLock); /* * Fetch any new security quals that must be applied to this RTE. */ get_row_security_policies(parsetree, rte, rt_index, &securityQuals, &withCheckOptions, &hasRowSecurity, &hasSubLinks); if (securityQuals != NIL || withCheckOptions != NIL) { if (hasSubLinks) { acquireLocksOnSubLinks_context context; fireRIRonSubLink_context fire_context; /* * Recursively process the new quals, checking for infinite * recursion. */ if (list_member_oid(activeRIRs, RelationGetRelid(rel))) ereport(ERROR, (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), errmsg("infinite recursion detected in policy for relation \"%s\"", RelationGetRelationName(rel)))); activeRIRs = lappend_oid(activeRIRs, RelationGetRelid(rel)); /* * get_row_security_policies just passed back securityQuals * and/or withCheckOptions, and there were SubLinks, make sure * we lock any relations which are referenced. * * These locks would normally be acquired by the parser, but * securityQuals and withCheckOptions are added post-parsing. */ context.for_execute = true; (void) acquireLocksOnSubLinks((Node *) securityQuals, &context); (void) acquireLocksOnSubLinks((Node *) withCheckOptions, &context); /* * Now that we have the locks on anything added by * get_row_security_policies, fire any RIR rules for them. */ fire_context.activeRIRs = activeRIRs; fire_context.hasRowSecurity = false; expression_tree_walker((Node *) securityQuals, fireRIRonSubLink, &fire_context); expression_tree_walker((Node *) withCheckOptions, fireRIRonSubLink, &fire_context); /* * We can ignore the value of fire_context.hasRowSecurity * since we only reach this code in cases where hasRowSecurity * is already true. */ Assert(hasRowSecurity); activeRIRs = list_delete_last(activeRIRs); } /* * Add the new security barrier quals to the start of the RTE's * list so that they get applied before any existing barrier quals * (which would have come from a security-barrier view, and should * get lower priority than RLS conditions on the table itself). */ rte->securityQuals = list_concat(securityQuals, rte->securityQuals); parsetree->withCheckOptions = list_concat(withCheckOptions, parsetree->withCheckOptions); } /* * Make sure the query is marked correctly if row-level security * applies, or if the new quals had sublinks. */ if (hasRowSecurity) parsetree->hasRowSecurity = true; if (hasSubLinks) parsetree->hasSubLinks = true; table_close(rel, NoLock); } return parsetree; } /* * Modify the given query by adding 'AND rule_qual IS NOT TRUE' to its * qualification. This is used to generate suitable "else clauses" for * conditional INSTEAD rules. (Unfortunately we must use "x IS NOT TRUE", * not just "NOT x" which the planner is much smarter about, else we will * do the wrong thing when the qual evaluates to NULL.) * * The rule_qual may contain references to OLD or NEW. OLD references are * replaced by references to the specified rt_index (the relation that the * rule applies to). NEW references are only possible for INSERT and UPDATE * queries on the relation itself, and so they should be replaced by copies * of the related entries in the query's own targetlist. */ static Query * CopyAndAddInvertedQual(Query *parsetree, Node *rule_qual, int rt_index, CmdType event) { /* Don't scribble on the passed qual (it's in the relcache!) */ Node *new_qual = copyObject(rule_qual); acquireLocksOnSubLinks_context context; context.for_execute = true; /* * In case there are subqueries in the qual, acquire necessary locks and * fix any deleted JOIN RTE entries. (This is somewhat redundant with * rewriteRuleAction, but not entirely ... consider restructuring so that * we only need to process the qual this way once.) */ (void) acquireLocksOnSubLinks(new_qual, &context); /* Fix references to OLD */ ChangeVarNodes(new_qual, PRS2_OLD_VARNO, rt_index, 0); /* Fix references to NEW */ if (event == CMD_INSERT || event == CMD_UPDATE) new_qual = ReplaceVarsFromTargetList(new_qual, PRS2_NEW_VARNO, 0, rt_fetch(rt_index, parsetree->rtable), parsetree->targetList, parsetree->resultRelation, (event == CMD_UPDATE) ? REPLACEVARS_CHANGE_VARNO : REPLACEVARS_SUBSTITUTE_NULL, rt_index, &parsetree->hasSubLinks); /* And attach the fixed qual */ AddInvertedQual(parsetree, new_qual); return parsetree; } /* * fireRules - * Iterate through rule locks applying rules. * * Input arguments: * parsetree - original query * rt_index - RT index of result relation in original query * event - type of rule event * locks - list of rules to fire * Output arguments: * *instead_flag - set true if any unqualified INSTEAD rule is found * (must be initialized to false) * *returning_flag - set true if we rewrite RETURNING clause in any rule * (must be initialized to false) * *qual_product - filled with modified original query if any qualified * INSTEAD rule is found (must be initialized to NULL) * Return value: * list of rule actions adjusted for use with this query * * Qualified INSTEAD rules generate their action with the qualification * condition added. They also generate a modified version of the original * query with the negated qualification added, so that it will run only for * rows that the qualified action doesn't act on. (If there are multiple * qualified INSTEAD rules, we AND all the negated quals onto a single * modified original query.) We won't execute the original, unmodified * query if we find either qualified or unqualified INSTEAD rules. If * we find both, the modified original query is discarded too. */ static List * fireRules(Query *parsetree, int rt_index, CmdType event, List *locks, bool *instead_flag, bool *returning_flag, Query **qual_product) { List *results = NIL; ListCell *l; foreach(l, locks) { RewriteRule *rule_lock = (RewriteRule *) lfirst(l); Node *event_qual = rule_lock->qual; List *actions = rule_lock->actions; QuerySource qsrc; ListCell *r; /* Determine correct QuerySource value for actions */ if (rule_lock->isInstead) { if (event_qual != NULL) qsrc = QSRC_QUAL_INSTEAD_RULE; else { qsrc = QSRC_INSTEAD_RULE; *instead_flag = true; /* report unqualified INSTEAD */ } } else qsrc = QSRC_NON_INSTEAD_RULE; if (qsrc == QSRC_QUAL_INSTEAD_RULE) { /* * If there are INSTEAD rules with qualifications, the original * query is still performed. But all the negated rule * qualifications of the INSTEAD rules are added so it does its * actions only in cases where the rule quals of all INSTEAD rules * are false. Think of it as the default action in a case. We save * this in *qual_product so RewriteQuery() can add it to the query * list after we mangled it up enough. * * If we have already found an unqualified INSTEAD rule, then * *qual_product won't be used, so don't bother building it. */ if (!*instead_flag) { if (*qual_product == NULL) *qual_product = copyObject(parsetree); *qual_product = CopyAndAddInvertedQual(*qual_product, event_qual, rt_index, event); } } /* Now process the rule's actions and add them to the result list */ foreach(r, actions) { Query *rule_action = lfirst(r); if (rule_action->commandType == CMD_NOTHING) continue; rule_action = rewriteRuleAction(parsetree, rule_action, event_qual, rt_index, event, returning_flag); rule_action->querySource = qsrc; rule_action->canSetTag = false; /* might change later */ results = lappend(results, rule_action); } } return results; } /* * get_view_query - get the Query from a view's _RETURN rule. * * Caller should have verified that the relation is a view, and therefore * we should find an ON SELECT action. * * Note that the pointer returned is into the relcache and therefore must * be treated as read-only to the caller and not modified or scribbled on. */ Query * get_view_query(Relation view) { int i; Assert(view->rd_rel->relkind == RELKIND_VIEW); for (i = 0; i < view->rd_rules->numLocks; i++) { RewriteRule *rule = view->rd_rules->rules[i]; if (rule->event == CMD_SELECT) { /* A _RETURN rule should have only one action */ if (list_length(rule->actions) != 1) elog(ERROR, "invalid _RETURN rule action specification"); return (Query *) linitial(rule->actions); } } elog(ERROR, "failed to find _RETURN rule for view"); return NULL; /* keep compiler quiet */ } /* * view_has_instead_trigger - does view have an INSTEAD OF trigger for event? * * If it does, we don't want to treat it as auto-updatable. This test can't * be folded into view_query_is_auto_updatable because it's not an error * condition. * * For MERGE, this will return true if there is an INSTEAD OF trigger for * every action in mergeActionList, and false if there are any actions that * lack an INSTEAD OF trigger. If there are no data-modifying MERGE actions * (only DO NOTHING actions), true is returned so that the view is treated * as trigger-updatable, rather than erroring out if it's not auto-updatable. */ bool view_has_instead_trigger(Relation view, CmdType event, List *mergeActionList) { TriggerDesc *trigDesc = view->trigdesc; switch (event) { case CMD_INSERT: if (trigDesc && trigDesc->trig_insert_instead_row) return true; break; case CMD_UPDATE: if (trigDesc && trigDesc->trig_update_instead_row) return true; break; case CMD_DELETE: if (trigDesc && trigDesc->trig_delete_instead_row) return true; break; case CMD_MERGE: foreach_node(MergeAction, action, mergeActionList) { switch (action->commandType) { case CMD_INSERT: if (!trigDesc || !trigDesc->trig_insert_instead_row) return false; break; case CMD_UPDATE: if (!trigDesc || !trigDesc->trig_update_instead_row) return false; break; case CMD_DELETE: if (!trigDesc || !trigDesc->trig_delete_instead_row) return false; break; case CMD_NOTHING: /* No trigger required */ break; default: elog(ERROR, "unrecognized commandType: %d", action->commandType); break; } } return true; /* no actions without an INSTEAD OF trigger */ default: elog(ERROR, "unrecognized CmdType: %d", (int) event); break; } return false; } /* * view_col_is_auto_updatable - test whether the specified column of a view * is auto-updatable. Returns NULL (if the column can be updated) or a message * string giving the reason that it cannot be. * * The returned string has not been translated; if it is shown as an error * message, the caller should apply _() to translate it. * * Note that the checks performed here are local to this view. We do not check * whether the referenced column of the underlying base relation is updatable. */ static const char * view_col_is_auto_updatable(RangeTblRef *rtr, TargetEntry *tle) { Var *var = (Var *) tle->expr; /* * For now, the only updatable columns we support are those that are Vars * referring to user columns of the underlying base relation. * * The view targetlist may contain resjunk columns (e.g., a view defined * like "SELECT * FROM t ORDER BY a+b" is auto-updatable) but such columns * are not auto-updatable, and in fact should never appear in the outer * query's targetlist. */ if (tle->resjunk) return gettext_noop("Junk view columns are not updatable."); if (!IsA(var, Var) || var->varno != rtr->rtindex || var->varlevelsup != 0) return gettext_noop("View columns that are not columns of their base relation are not updatable."); if (var->varattno < 0) return gettext_noop("View columns that refer to system columns are not updatable."); if (var->varattno == 0) return gettext_noop("View columns that return whole-row references are not updatable."); return NULL; /* the view column is updatable */ } /* * view_query_is_auto_updatable - test whether the specified view definition * represents an auto-updatable view. Returns NULL (if the view can be updated) * or a message string giving the reason that it cannot be. * The returned string has not been translated; if it is shown as an error * message, the caller should apply _() to translate it. * * If check_cols is true, the view is required to have at least one updatable * column (necessary for INSERT/UPDATE). Otherwise the view's columns are not * checked for updatability. See also view_cols_are_auto_updatable. * * Note that the checks performed here are only based on the view definition. * We do not check whether any base relations referred to by the view are * updatable. */ const char * view_query_is_auto_updatable(Query *viewquery, bool check_cols) { RangeTblRef *rtr; RangeTblEntry *base_rte; /*---------- * Check if the view is simply updatable. According to SQL-92 this means: * - No DISTINCT clause. * - Each TLE is a column reference, and each column appears at most once. * - FROM contains exactly one base relation. * - No GROUP BY or HAVING clauses. * - No set operations (UNION, INTERSECT or EXCEPT). * - No sub-queries in the WHERE clause that reference the target table. * * We ignore that last restriction since it would be complex to enforce * and there isn't any actual benefit to disallowing sub-queries. (The * semantic issues that the standard is presumably concerned about don't * arise in Postgres, since any such sub-query will not see any updates * executed by the outer query anyway, thanks to MVCC snapshotting.) * * We also relax the second restriction by supporting part of SQL:1999 * feature T111, which allows for a mix of updatable and non-updatable * columns, provided that an INSERT or UPDATE doesn't attempt to assign to * a non-updatable column. * * In addition we impose these constraints, involving features that are * not part of SQL-92: * - No CTEs (WITH clauses). * - No OFFSET or LIMIT clauses (this matches a SQL:2008 restriction). * - No system columns (including whole-row references) in the tlist. * - No window functions in the tlist. * - No set-returning functions in the tlist. * * Note that we do these checks without recursively expanding the view. * If the base relation is a view, we'll recursively deal with it later. *---------- */ if (viewquery->distinctClause != NIL) return gettext_noop("Views containing DISTINCT are not automatically updatable."); if (viewquery->groupClause != NIL || viewquery->groupingSets) return gettext_noop("Views containing GROUP BY are not automatically updatable."); if (viewquery->havingQual != NULL) return gettext_noop("Views containing HAVING are not automatically updatable."); if (viewquery->setOperations != NULL) return gettext_noop("Views containing UNION, INTERSECT, or EXCEPT are not automatically updatable."); if (viewquery->cteList != NIL) return gettext_noop("Views containing WITH are not automatically updatable."); if (viewquery->limitOffset != NULL || viewquery->limitCount != NULL) return gettext_noop("Views containing LIMIT or OFFSET are not automatically updatable."); /* * We must not allow window functions or set returning functions in the * targetlist. Otherwise we might end up inserting them into the quals of * the main query. We must also check for aggregates in the targetlist in * case they appear without a GROUP BY. * * These restrictions ensure that each row of the view corresponds to a * unique row in the underlying base relation. */ if (viewquery->hasAggs) return gettext_noop("Views that return aggregate functions are not automatically updatable."); if (viewquery->hasWindowFuncs) return gettext_noop("Views that return window functions are not automatically updatable."); if (viewquery->hasTargetSRFs) return gettext_noop("Views that return set-returning functions are not automatically updatable."); /* * The view query should select from a single base relation, which must be * a table or another view. */ if (list_length(viewquery->jointree->fromlist) != 1) return gettext_noop("Views that do not select from a single table or view are not automatically updatable."); rtr = (RangeTblRef *) linitial(viewquery->jointree->fromlist); if (!IsA(rtr, RangeTblRef)) return gettext_noop("Views that do not select from a single table or view are not automatically updatable."); base_rte = rt_fetch(rtr->rtindex, viewquery->rtable); if (base_rte->rtekind != RTE_RELATION || (base_rte->relkind != RELKIND_RELATION && base_rte->relkind != RELKIND_FOREIGN_TABLE && base_rte->relkind != RELKIND_VIEW && base_rte->relkind != RELKIND_PARTITIONED_TABLE)) return gettext_noop("Views that do not select from a single table or view are not automatically updatable."); if (base_rte->tablesample) return gettext_noop("Views containing TABLESAMPLE are not automatically updatable."); /* * Check that the view has at least one updatable column. This is required * for INSERT/UPDATE but not for DELETE. */ if (check_cols) { ListCell *cell; bool found; found = false; foreach(cell, viewquery->targetList) { TargetEntry *tle = (TargetEntry *) lfirst(cell); if (view_col_is_auto_updatable(rtr, tle) == NULL) { found = true; break; } } if (!found) return gettext_noop("Views that have no updatable columns are not automatically updatable."); } return NULL; /* the view is updatable */ } /* * view_cols_are_auto_updatable - test whether all of the required columns of * an auto-updatable view are actually updatable. Returns NULL (if all the * required columns can be updated) or a message string giving the reason that * they cannot be. * * The returned string has not been translated; if it is shown as an error * message, the caller should apply _() to translate it. * * This should be used for INSERT/UPDATE to ensure that we don't attempt to * assign to any non-updatable columns. * * Additionally it may be used to retrieve the set of updatable columns in the * view, or if one or more of the required columns is not updatable, the name * of the first offending non-updatable column. * * The caller must have already verified that this is an auto-updatable view * using view_query_is_auto_updatable. * * Note that the checks performed here are only based on the view definition. * We do not check whether the referenced columns of the base relation are * updatable. */ static const char * view_cols_are_auto_updatable(Query *viewquery, Bitmapset *required_cols, Bitmapset **updatable_cols, char **non_updatable_col) { RangeTblRef *rtr; AttrNumber col; ListCell *cell; /* * The caller should have verified that this view is auto-updatable and so * there should be a single base relation. */ Assert(list_length(viewquery->jointree->fromlist) == 1); rtr = linitial_node(RangeTblRef, viewquery->jointree->fromlist); /* Initialize the optional return values */ if (updatable_cols != NULL) *updatable_cols = NULL; if (non_updatable_col != NULL) *non_updatable_col = NULL; /* Test each view column for updatability */ col = -FirstLowInvalidHeapAttributeNumber; foreach(cell, viewquery->targetList) { TargetEntry *tle = (TargetEntry *) lfirst(cell); const char *col_update_detail; col++; col_update_detail = view_col_is_auto_updatable(rtr, tle); if (col_update_detail == NULL) { /* The column is updatable */ if (updatable_cols != NULL) *updatable_cols = bms_add_member(*updatable_cols, col); } else if (bms_is_member(col, required_cols)) { /* The required column is not updatable */ if (non_updatable_col != NULL) *non_updatable_col = tle->resname; return col_update_detail; } } return NULL; /* all the required view columns are updatable */ } /* * relation_is_updatable - determine which update events the specified * relation supports. * * Note that views may contain a mix of updatable and non-updatable columns. * For a view to support INSERT/UPDATE it must have at least one updatable * column, but there is no such restriction for DELETE. If include_cols is * non-NULL, then only the specified columns are considered when testing for * updatability. * * Unlike the preceding functions, this does recurse to look at a view's * base relations, so it needs to detect recursion. To do that, we pass * a list of currently-considered outer relations. External callers need * only pass NIL. * * This is used for the information_schema views, which have separate concepts * of "updatable" and "trigger updatable". A relation is "updatable" if it * can be updated without the need for triggers (either because it has a * suitable RULE, or because it is simple enough to be automatically updated). * A relation is "trigger updatable" if it has a suitable INSTEAD OF trigger. * The SQL standard regards this as not necessarily updatable, presumably * because there is no way of knowing what the trigger will actually do. * The information_schema views therefore call this function with * include_triggers = false. However, other callers might only care whether * data-modifying SQL will work, so they can pass include_triggers = true * to have trigger updatability included in the result. * * The return value is a bitmask of rule event numbers indicating which of * the INSERT, UPDATE and DELETE operations are supported. (We do it this way * so that we can test for UPDATE plus DELETE support in a single call.) */ int relation_is_updatable(Oid reloid, List *outer_reloids, bool include_triggers, Bitmapset *include_cols) { int events = 0; Relation rel; RuleLock *rulelocks; #define ALL_EVENTS ((1 << CMD_INSERT) | (1 << CMD_UPDATE) | (1 << CMD_DELETE)) /* Since this function recurses, it could be driven to stack overflow */ check_stack_depth(); rel = try_relation_open(reloid, AccessShareLock); /* * If the relation doesn't exist, return zero rather than throwing an * error. This is helpful since scanning an information_schema view under * MVCC rules can result in referencing rels that have actually been * deleted already. */ if (rel == NULL) return 0; /* If we detect a recursive view, report that it is not updatable */ if (list_member_oid(outer_reloids, RelationGetRelid(rel))) { relation_close(rel, AccessShareLock); return 0; } /* If the relation is a table, it is always updatable */ if (rel->rd_rel->relkind == RELKIND_RELATION || rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE) { relation_close(rel, AccessShareLock); return ALL_EVENTS; } /* Look for unconditional DO INSTEAD rules, and note supported events */ rulelocks = rel->rd_rules; if (rulelocks != NULL) { int i; for (i = 0; i < rulelocks->numLocks; i++) { if (rulelocks->rules[i]->isInstead && rulelocks->rules[i]->qual == NULL) { events |= ((1 << rulelocks->rules[i]->event) & ALL_EVENTS); } } /* If we have rules for all events, we're done */ if (events == ALL_EVENTS) { relation_close(rel, AccessShareLock); return events; } } /* Similarly look for INSTEAD OF triggers, if they are to be included */ if (include_triggers) { TriggerDesc *trigDesc = rel->trigdesc; if (trigDesc) { if (trigDesc->trig_insert_instead_row) events |= (1 << CMD_INSERT); if (trigDesc->trig_update_instead_row) events |= (1 << CMD_UPDATE); if (trigDesc->trig_delete_instead_row) events |= (1 << CMD_DELETE); /* If we have triggers for all events, we're done */ if (events == ALL_EVENTS) { relation_close(rel, AccessShareLock); return events; } } } /* If this is a foreign table, check which update events it supports */ if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE) { FdwRoutine *fdwroutine = GetFdwRoutineForRelation(rel, false); if (fdwroutine->IsForeignRelUpdatable != NULL) events |= fdwroutine->IsForeignRelUpdatable(rel); else { /* Assume presence of executor functions is sufficient */ if (fdwroutine->ExecForeignInsert != NULL) events |= (1 << CMD_INSERT); if (fdwroutine->ExecForeignUpdate != NULL) events |= (1 << CMD_UPDATE); if (fdwroutine->ExecForeignDelete != NULL) events |= (1 << CMD_DELETE); } relation_close(rel, AccessShareLock); return events; } /* Check if this is an automatically updatable view */ if (rel->rd_rel->relkind == RELKIND_VIEW) { Query *viewquery = get_view_query(rel); if (view_query_is_auto_updatable(viewquery, false) == NULL) { Bitmapset *updatable_cols; int auto_events; RangeTblRef *rtr; RangeTblEntry *base_rte; Oid baseoid; /* * Determine which of the view's columns are updatable. If there * are none within the set of columns we are looking at, then the * view doesn't support INSERT/UPDATE, but it may still support * DELETE. */ view_cols_are_auto_updatable(viewquery, NULL, &updatable_cols, NULL); if (include_cols != NULL) updatable_cols = bms_int_members(updatable_cols, include_cols); if (bms_is_empty(updatable_cols)) auto_events = (1 << CMD_DELETE); /* May support DELETE */ else auto_events = ALL_EVENTS; /* May support all events */ /* * The base relation must also support these update commands. * Tables are always updatable, but for any other kind of base * relation we must do a recursive check limited to the columns * referenced by the locally updatable columns in this view. */ rtr = (RangeTblRef *) linitial(viewquery->jointree->fromlist); base_rte = rt_fetch(rtr->rtindex, viewquery->rtable); Assert(base_rte->rtekind == RTE_RELATION); if (base_rte->relkind != RELKIND_RELATION && base_rte->relkind != RELKIND_PARTITIONED_TABLE) { baseoid = base_rte->relid; outer_reloids = lappend_oid(outer_reloids, RelationGetRelid(rel)); include_cols = adjust_view_column_set(updatable_cols, viewquery->targetList); auto_events &= relation_is_updatable(baseoid, outer_reloids, include_triggers, include_cols); outer_reloids = list_delete_last(outer_reloids); } events |= auto_events; } } /* If we reach here, the relation may support some update commands */ relation_close(rel, AccessShareLock); return events; } /* * adjust_view_column_set - map a set of column numbers according to targetlist * * This is used with simply-updatable views to map column-permissions sets for * the view columns onto the matching columns in the underlying base relation. * Relevant entries in the targetlist must be plain Vars of the underlying * relation (as per the checks above in view_query_is_auto_updatable). */ static Bitmapset * adjust_view_column_set(Bitmapset *cols, List *targetlist) { Bitmapset *result = NULL; int col; col = -1; while ((col = bms_next_member(cols, col)) >= 0) { /* bit numbers are offset by FirstLowInvalidHeapAttributeNumber */ AttrNumber attno = col + FirstLowInvalidHeapAttributeNumber; if (attno == InvalidAttrNumber) { /* * There's a whole-row reference to the view. For permissions * purposes, treat it as a reference to each column available from * the view. (We should *not* convert this to a whole-row * reference to the base relation, since the view may not touch * all columns of the base relation.) */ ListCell *lc; foreach(lc, targetlist) { TargetEntry *tle = lfirst_node(TargetEntry, lc); Var *var; if (tle->resjunk) continue; var = castNode(Var, tle->expr); result = bms_add_member(result, var->varattno - FirstLowInvalidHeapAttributeNumber); } } else { /* * Views do not have system columns, so we do not expect to see * any other system attnos here. If we do find one, the error * case will apply. */ TargetEntry *tle = get_tle_by_resno(targetlist, attno); if (tle != NULL && !tle->resjunk && IsA(tle->expr, Var)) { Var *var = (Var *) tle->expr; result = bms_add_member(result, var->varattno - FirstLowInvalidHeapAttributeNumber); } else elog(ERROR, "attribute number %d not found in view targetlist", attno); } } return result; } /* * error_view_not_updatable - * Report an error due to an attempt to update a non-updatable view. * * Generally this is expected to be called from the rewriter, with suitable * error detail explaining why the view is not updatable. Note, however, that * the executor also performs a just-in-case check that the target view is * updatable. That check is expected to never fail, but if it does, it will * call this function with NULL error detail --- see CheckValidResultRel(). * * Note: for MERGE, at least one of the actions in mergeActionList is expected * to lack a suitable INSTEAD OF trigger --- see view_has_instead_trigger(). */ void error_view_not_updatable(Relation view, CmdType command, List *mergeActionList, const char *detail) { TriggerDesc *trigDesc = view->trigdesc; switch (command) { case CMD_INSERT: ereport(ERROR, errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("cannot insert into view \"%s\"", RelationGetRelationName(view)), detail ? errdetail_internal("%s", _(detail)) : 0, errhint("To enable inserting into the view, provide an INSTEAD OF INSERT trigger or an unconditional ON INSERT DO INSTEAD rule.")); break; case CMD_UPDATE: ereport(ERROR, errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("cannot update view \"%s\"", RelationGetRelationName(view)), detail ? errdetail_internal("%s", _(detail)) : 0, errhint("To enable updating the view, provide an INSTEAD OF UPDATE trigger or an unconditional ON UPDATE DO INSTEAD rule.")); break; case CMD_DELETE: ereport(ERROR, errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("cannot delete from view \"%s\"", RelationGetRelationName(view)), detail ? errdetail_internal("%s", _(detail)) : 0, errhint("To enable deleting from the view, provide an INSTEAD OF DELETE trigger or an unconditional ON DELETE DO INSTEAD rule.")); break; case CMD_MERGE: /* * Note that the error hints here differ from above, since MERGE * doesn't support rules. */ foreach_node(MergeAction, action, mergeActionList) { switch (action->commandType) { case CMD_INSERT: if (!trigDesc || !trigDesc->trig_insert_instead_row) ereport(ERROR, errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("cannot insert into view \"%s\"", RelationGetRelationName(view)), detail ? errdetail_internal("%s", _(detail)) : 0, errhint("To enable inserting into the view using MERGE, provide an INSTEAD OF INSERT trigger.")); break; case CMD_UPDATE: if (!trigDesc || !trigDesc->trig_update_instead_row) ereport(ERROR, errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("cannot update view \"%s\"", RelationGetRelationName(view)), detail ? errdetail_internal("%s", _(detail)) : 0, errhint("To enable updating the view using MERGE, provide an INSTEAD OF UPDATE trigger.")); break; case CMD_DELETE: if (!trigDesc || !trigDesc->trig_delete_instead_row) ereport(ERROR, errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("cannot delete from view \"%s\"", RelationGetRelationName(view)), detail ? errdetail_internal("%s", _(detail)) : 0, errhint("To enable deleting from the view using MERGE, provide an INSTEAD OF DELETE trigger.")); break; case CMD_NOTHING: break; default: elog(ERROR, "unrecognized commandType: %d", action->commandType); break; } } break; default: elog(ERROR, "unrecognized CmdType: %d", (int) command); break; } } /* * rewriteTargetView - * Attempt to rewrite a query where the target relation is a view, so that * the view's base relation becomes the target relation. * * Note that the base relation here may itself be a view, which may or may not * have INSTEAD OF triggers or rules to handle the update. That is handled by * the recursion in RewriteQuery. */ static Query * rewriteTargetView(Query *parsetree, Relation view) { Query *viewquery; bool insert_or_update; const char *auto_update_detail; RangeTblRef *rtr; int base_rt_index; int new_rt_index; RangeTblEntry *base_rte; RangeTblEntry *view_rte; RangeTblEntry *new_rte; RTEPermissionInfo *base_perminfo; RTEPermissionInfo *view_perminfo; RTEPermissionInfo *new_perminfo; Relation base_rel; List *view_targetlist; ListCell *lc; /* * Get the Query from the view's ON SELECT rule. We're going to munge the * Query to change the view's base relation into the target relation, * along with various other changes along the way, so we need to make a * copy of it (get_view_query() returns a pointer into the relcache, so we * have to treat it as read-only). */ viewquery = copyObject(get_view_query(view)); /* Locate RTE and perminfo describing the view in the outer query */ view_rte = rt_fetch(parsetree->resultRelation, parsetree->rtable); view_perminfo = getRTEPermissionInfo(parsetree->rteperminfos, view_rte); /* * Are we doing INSERT/UPDATE, or MERGE containing INSERT/UPDATE? If so, * various additional checks on the view columns need to be applied, and * any view CHECK OPTIONs need to be enforced. */ insert_or_update = (parsetree->commandType == CMD_INSERT || parsetree->commandType == CMD_UPDATE); if (parsetree->commandType == CMD_MERGE) { foreach_node(MergeAction, action, parsetree->mergeActionList) { if (action->commandType == CMD_INSERT || action->commandType == CMD_UPDATE) { insert_or_update = true; break; } } } /* Check if the expansion of non-system views are restricted */ if (unlikely((restrict_nonsystem_relation_kind & RESTRICT_RELKIND_VIEW) != 0 && RelationGetRelid(view) >= FirstNormalObjectId)) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("access to non-system view \"%s\" is restricted", RelationGetRelationName(view)))); /* * The view must be updatable, else fail. * * If we are doing INSERT/UPDATE (or MERGE containing INSERT/UPDATE), we * also check that there is at least one updatable column. */ auto_update_detail = view_query_is_auto_updatable(viewquery, insert_or_update); if (auto_update_detail) error_view_not_updatable(view, parsetree->commandType, parsetree->mergeActionList, auto_update_detail); /* * For INSERT/UPDATE (or MERGE containing INSERT/UPDATE) the modified * columns must all be updatable. */ if (insert_or_update) { Bitmapset *modified_cols; char *non_updatable_col; /* * Compute the set of modified columns as those listed in the result * RTE's insertedCols and/or updatedCols sets plus those that are * targets of the query's targetlist(s). We must consider the query's * targetlist because rewriteTargetListIU may have added additional * targetlist entries for view defaults, and these must also be * updatable. But rewriteTargetListIU can also remove entries if they * are DEFAULT markers and the column's default is NULL, so * considering only the targetlist would also be wrong. */ modified_cols = bms_union(view_perminfo->insertedCols, view_perminfo->updatedCols); foreach(lc, parsetree->targetList) { TargetEntry *tle = (TargetEntry *) lfirst(lc); if (!tle->resjunk) modified_cols = bms_add_member(modified_cols, tle->resno - FirstLowInvalidHeapAttributeNumber); } if (parsetree->onConflict) { foreach(lc, parsetree->onConflict->onConflictSet) { TargetEntry *tle = (TargetEntry *) lfirst(lc); if (!tle->resjunk) modified_cols = bms_add_member(modified_cols, tle->resno - FirstLowInvalidHeapAttributeNumber); } } foreach_node(MergeAction, action, parsetree->mergeActionList) { if (action->commandType == CMD_INSERT || action->commandType == CMD_UPDATE) { foreach_node(TargetEntry, tle, action->targetList) { if (!tle->resjunk) modified_cols = bms_add_member(modified_cols, tle->resno - FirstLowInvalidHeapAttributeNumber); } } } auto_update_detail = view_cols_are_auto_updatable(viewquery, modified_cols, NULL, &non_updatable_col); if (auto_update_detail) { /* * This is a different error, caused by an attempt to update a * non-updatable column in an otherwise updatable view. */ switch (parsetree->commandType) { case CMD_INSERT: ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot insert into column \"%s\" of view \"%s\"", non_updatable_col, RelationGetRelationName(view)), errdetail_internal("%s", _(auto_update_detail)))); break; case CMD_UPDATE: ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot update column \"%s\" of view \"%s\"", non_updatable_col, RelationGetRelationName(view)), errdetail_internal("%s", _(auto_update_detail)))); break; case CMD_MERGE: ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot merge into column \"%s\" of view \"%s\"", non_updatable_col, RelationGetRelationName(view)), errdetail_internal("%s", _(auto_update_detail)))); break; default: elog(ERROR, "unrecognized CmdType: %d", (int) parsetree->commandType); break; } } } /* * For MERGE, there must not be any INSTEAD OF triggers on an otherwise * updatable view. The caller already checked that there isn't a full set * of INSTEAD OF triggers, so this is to guard against having a partial * set (mixing auto-update and trigger-update actions in a single command * isn't supported). */ if (parsetree->commandType == CMD_MERGE) { foreach_node(MergeAction, action, parsetree->mergeActionList) { if (action->commandType != CMD_NOTHING && view_has_instead_trigger(view, action->commandType, NIL)) ereport(ERROR, errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot merge into view \"%s\"", RelationGetRelationName(view)), errdetail("MERGE is not supported for views with INSTEAD OF triggers for some actions but not all."), errhint("To enable merging into the view, either provide a full set of INSTEAD OF triggers or drop the existing INSTEAD OF triggers.")); } } /* * If we get here, view_query_is_auto_updatable() has verified that the * view contains a single base relation. */ Assert(list_length(viewquery->jointree->fromlist) == 1); rtr = linitial_node(RangeTblRef, viewquery->jointree->fromlist); base_rt_index = rtr->rtindex; base_rte = rt_fetch(base_rt_index, viewquery->rtable); Assert(base_rte->rtekind == RTE_RELATION); base_perminfo = getRTEPermissionInfo(viewquery->rteperminfos, base_rte); /* * Up to now, the base relation hasn't been touched at all in our query. * We need to acquire lock on it before we try to do anything with it. * (The subsequent recursive call of RewriteQuery will suppose that we * already have the right lock!) Since it will become the query target * relation, RowExclusiveLock is always the right thing. */ base_rel = table_open(base_rte->relid, RowExclusiveLock); /* * While we have the relation open, update the RTE's relkind, just in case * it changed since this view was made (cf. AcquireRewriteLocks). */ base_rte->relkind = base_rel->rd_rel->relkind; /* * If the view query contains any sublink subqueries then we need to also * acquire locks on any relations they refer to. We know that there won't * be any subqueries in the range table or CTEs, so we can skip those, as * in AcquireRewriteLocks. */ if (viewquery->hasSubLinks) { acquireLocksOnSubLinks_context context; context.for_execute = true; query_tree_walker(viewquery, acquireLocksOnSubLinks, &context, QTW_IGNORE_RC_SUBQUERIES); } /* * Create a new target RTE describing the base relation, and add it to the * outer query's rangetable. (What's happening in the next few steps is * very much like what the planner would do to "pull up" the view into the * outer query. Perhaps someday we should refactor things enough so that * we can share code with the planner.) * * Be sure to set rellockmode to the correct thing for the target table. * Since we copied the whole viewquery above, we can just scribble on * base_rte instead of copying it. */ new_rte = base_rte; new_rte->rellockmode = RowExclusiveLock; parsetree->rtable = lappend(parsetree->rtable, new_rte); new_rt_index = list_length(parsetree->rtable); /* * INSERTs never inherit. For UPDATE/DELETE/MERGE, we use the view * query's inheritance flag for the base relation. */ if (parsetree->commandType == CMD_INSERT) new_rte->inh = false; /* * Adjust the view's targetlist Vars to reference the new target RTE, ie * make their varnos be new_rt_index instead of base_rt_index. There can * be no Vars for other rels in the tlist, so this is sufficient to pull * up the tlist expressions for use in the outer query. The tlist will * provide the replacement expressions used by ReplaceVarsFromTargetList * below. */ view_targetlist = viewquery->targetList; ChangeVarNodes((Node *) view_targetlist, base_rt_index, new_rt_index, 0); /* * If the view has "security_invoker" set, mark the new target relation * for the permissions checks that we want to enforce against the query * caller. Otherwise we want to enforce them against the view owner. * * At the relation level, require the same INSERT/UPDATE/DELETE * permissions that the query caller needs against the view. We drop the * ACL_SELECT bit that is presumably in new_perminfo->requiredPerms * initially. * * Note: the original view's RTEPermissionInfo remains in the query's * rteperminfos so that the executor still performs appropriate * permissions checks for the query caller's use of the view. * * Disregard the perminfo in viewquery->rteperminfos that the base_rte * would currently be pointing at, because we'd like it to point now to a * new one that will be filled below. Must set perminfoindex to 0 to not * trip over the Assert in addRTEPermissionInfo(). */ new_rte->perminfoindex = 0; new_perminfo = addRTEPermissionInfo(&parsetree->rteperminfos, new_rte); if (RelationHasSecurityInvoker(view)) new_perminfo->checkAsUser = InvalidOid; else new_perminfo->checkAsUser = view->rd_rel->relowner; new_perminfo->requiredPerms = view_perminfo->requiredPerms; /* * Now for the per-column permissions bits. * * Initially, new_perminfo (base_perminfo) contains selectedCols * permission check bits for all base-rel columns referenced by the view, * but since the view is a SELECT query its insertedCols/updatedCols is * empty. We set insertedCols and updatedCols to include all the columns * the outer query is trying to modify, adjusting the column numbers as * needed. But we leave selectedCols as-is, so the view owner must have * read permission for all columns used in the view definition, even if * some of them are not read by the outer query. We could try to limit * selectedCols to only columns used in the transformed query, but that * does not correspond to what happens in ordinary SELECT usage of a view: * all referenced columns must have read permission, even if optimization * finds that some of them can be discarded during query transformation. * The flattening we're doing here is an optional optimization, too. (If * you are unpersuaded and want to change this, note that applying * adjust_view_column_set to view_perminfo->selectedCols is clearly *not* * the right answer, since that neglects base-rel columns used in the * view's WHERE quals.) * * This step needs the modified view targetlist, so we have to do things * in this order. */ Assert(bms_is_empty(new_perminfo->insertedCols) && bms_is_empty(new_perminfo->updatedCols)); new_perminfo->selectedCols = base_perminfo->selectedCols; new_perminfo->insertedCols = adjust_view_column_set(view_perminfo->insertedCols, view_targetlist); new_perminfo->updatedCols = adjust_view_column_set(view_perminfo->updatedCols, view_targetlist); /* * Move any security barrier quals from the view RTE onto the new target * RTE. Any such quals should now apply to the new target RTE and will * not reference the original view RTE in the rewritten query. */ new_rte->securityQuals = view_rte->securityQuals; view_rte->securityQuals = NIL; /* * Now update all Vars in the outer query that reference the view to * reference the appropriate column of the base relation instead. */ parsetree = (Query *) ReplaceVarsFromTargetList((Node *) parsetree, parsetree->resultRelation, 0, view_rte, view_targetlist, new_rt_index, REPLACEVARS_REPORT_ERROR, 0, NULL); /* * Update all other RTI references in the query that point to the view * (for example, parsetree->resultRelation itself) to point to the new * base relation instead. Vars will not be affected since none of them * reference parsetree->resultRelation any longer. */ ChangeVarNodes((Node *) parsetree, parsetree->resultRelation, new_rt_index, 0); Assert(parsetree->resultRelation == new_rt_index); /* * For INSERT/UPDATE we must also update resnos in the targetlist to refer * to columns of the base relation, since those indicate the target * columns to be affected. Similarly, for MERGE we must update the resnos * in the merge action targetlists of any INSERT/UPDATE actions. * * Note that this destroys the resno ordering of the targetlists, but that * will be fixed when we recurse through RewriteQuery, which will invoke * rewriteTargetListIU again on the updated targetlists. */ if (parsetree->commandType != CMD_DELETE) { foreach(lc, parsetree->targetList) { TargetEntry *tle = (TargetEntry *) lfirst(lc); TargetEntry *view_tle; if (tle->resjunk) continue; view_tle = get_tle_by_resno(view_targetlist, tle->resno); if (view_tle != NULL && !view_tle->resjunk && IsA(view_tle->expr, Var)) tle->resno = ((Var *) view_tle->expr)->varattno; else elog(ERROR, "attribute number %d not found in view targetlist", tle->resno); } foreach_node(MergeAction, action, parsetree->mergeActionList) { if (action->commandType == CMD_INSERT || action->commandType == CMD_UPDATE) { foreach_node(TargetEntry, tle, action->targetList) { TargetEntry *view_tle; if (tle->resjunk) continue; view_tle = get_tle_by_resno(view_targetlist, tle->resno); if (view_tle != NULL && !view_tle->resjunk && IsA(view_tle->expr, Var)) tle->resno = ((Var *) view_tle->expr)->varattno; else elog(ERROR, "attribute number %d not found in view targetlist", tle->resno); } } } } /* * For INSERT .. ON CONFLICT .. DO UPDATE, we must also update assorted * stuff in the onConflict data structure. */ if (parsetree->onConflict && parsetree->onConflict->action == ONCONFLICT_UPDATE) { Index old_exclRelIndex, new_exclRelIndex; ParseNamespaceItem *new_exclNSItem; RangeTblEntry *new_exclRte; List *tmp_tlist; /* * Like the INSERT/UPDATE code above, update the resnos in the * auxiliary UPDATE targetlist to refer to columns of the base * relation. */ foreach(lc, parsetree->onConflict->onConflictSet) { TargetEntry *tle = (TargetEntry *) lfirst(lc); TargetEntry *view_tle; if (tle->resjunk) continue; view_tle = get_tle_by_resno(view_targetlist, tle->resno); if (view_tle != NULL && !view_tle->resjunk && IsA(view_tle->expr, Var)) tle->resno = ((Var *) view_tle->expr)->varattno; else elog(ERROR, "attribute number %d not found in view targetlist", tle->resno); } /* * Also, create a new RTE for the EXCLUDED pseudo-relation, using the * query's new base rel (which may well have a different column list * from the view, hence we need a new column alias list). This should * match transformOnConflictClause. In particular, note that the * relkind is set to composite to signal that we're not dealing with * an actual relation. */ old_exclRelIndex = parsetree->onConflict->exclRelIndex; new_exclNSItem = addRangeTableEntryForRelation(make_parsestate(NULL), base_rel, RowExclusiveLock, makeAlias("excluded", NIL), false, false); new_exclRte = new_exclNSItem->p_rte; new_exclRte->relkind = RELKIND_COMPOSITE_TYPE; /* Ignore the RTEPermissionInfo that would've been added. */ new_exclRte->perminfoindex = 0; parsetree->rtable = lappend(parsetree->rtable, new_exclRte); new_exclRelIndex = parsetree->onConflict->exclRelIndex = list_length(parsetree->rtable); /* * Replace the targetlist for the EXCLUDED pseudo-relation with a new * one, representing the columns from the new base relation. */ parsetree->onConflict->exclRelTlist = BuildOnConflictExcludedTargetlist(base_rel, new_exclRelIndex); /* * Update all Vars in the ON CONFLICT clause that refer to the old * EXCLUDED pseudo-relation. We want to use the column mappings * defined in the view targetlist, but we need the outputs to refer to * the new EXCLUDED pseudo-relation rather than the new target RTE. * Also notice that "EXCLUDED.*" will be expanded using the view's * rowtype, which seems correct. */ tmp_tlist = copyObject(view_targetlist); ChangeVarNodes((Node *) tmp_tlist, new_rt_index, new_exclRelIndex, 0); parsetree->onConflict = (OnConflictExpr *) ReplaceVarsFromTargetList((Node *) parsetree->onConflict, old_exclRelIndex, 0, view_rte, tmp_tlist, new_rt_index, REPLACEVARS_REPORT_ERROR, 0, &parsetree->hasSubLinks); } /* * For UPDATE/DELETE/MERGE, pull up any WHERE quals from the view. We * know that any Vars in the quals must reference the one base relation, * so we need only adjust their varnos to reference the new target (just * the same as we did with the view targetlist). * * If it's a security-barrier view, its WHERE quals must be applied before * quals from the outer query, so we attach them to the RTE as security * barrier quals rather than adding them to the main WHERE clause. * * For INSERT, the view's quals can be ignored in the main query. */ if (parsetree->commandType != CMD_INSERT && viewquery->jointree->quals != NULL) { Node *viewqual = (Node *) viewquery->jointree->quals; /* * Even though we copied viewquery already at the top of this * function, we must duplicate the viewqual again here, because we may * need to use the quals again below for a WithCheckOption clause. */ viewqual = copyObject(viewqual); ChangeVarNodes(viewqual, base_rt_index, new_rt_index, 0); if (RelationIsSecurityView(view)) { /* * The view's quals go in front of existing barrier quals: those * would have come from an outer level of security-barrier view, * and so must get evaluated later. * * Note: the parsetree has been mutated, so the new_rte pointer is * stale and needs to be re-computed. */ new_rte = rt_fetch(new_rt_index, parsetree->rtable); new_rte->securityQuals = lcons(viewqual, new_rte->securityQuals); /* * Do not set parsetree->hasRowSecurity, because these aren't RLS * conditions (they aren't affected by enabling/disabling RLS). */ /* * Make sure that the query is marked correctly if the added qual * has sublinks. */ if (!parsetree->hasSubLinks) parsetree->hasSubLinks = checkExprHasSubLink(viewqual); } else AddQual(parsetree, (Node *) viewqual); } /* * For INSERT/UPDATE (or MERGE containing INSERT/UPDATE), if the view has * the WITH CHECK OPTION, or any parent view specified WITH CASCADED CHECK * OPTION, add the quals from the view to the query's withCheckOptions * list. */ if (insert_or_update) { bool has_wco = RelationHasCheckOption(view); bool cascaded = RelationHasCascadedCheckOption(view); /* * If the parent view has a cascaded check option, treat this view as * if it also had a cascaded check option. * * New WithCheckOptions are added to the start of the list, so if * there is a cascaded check option, it will be the first item in the * list. */ if (parsetree->withCheckOptions != NIL) { WithCheckOption *parent_wco = (WithCheckOption *) linitial(parsetree->withCheckOptions); if (parent_wco->cascaded) { has_wco = true; cascaded = true; } } /* * Add the new WithCheckOption to the start of the list, so that * checks on inner views are run before checks on outer views, as * required by the SQL standard. * * If the new check is CASCADED, we need to add it even if this view * has no quals, since there may be quals on child views. A LOCAL * check can be omitted if this view has no quals. */ if (has_wco && (cascaded || viewquery->jointree->quals != NULL)) { WithCheckOption *wco; wco = makeNode(WithCheckOption); wco->kind = WCO_VIEW_CHECK; wco->relname = pstrdup(RelationGetRelationName(view)); wco->polname = NULL; wco->qual = NULL; wco->cascaded = cascaded; parsetree->withCheckOptions = lcons(wco, parsetree->withCheckOptions); if (viewquery->jointree->quals != NULL) { wco->qual = (Node *) viewquery->jointree->quals; ChangeVarNodes(wco->qual, base_rt_index, new_rt_index, 0); /* * For INSERT, make sure that the query is marked correctly if * the added qual has sublinks. This can be skipped for * UPDATE/MERGE, since the same qual will have already been * added above, and the check will already have been done. */ if (!parsetree->hasSubLinks && parsetree->commandType == CMD_INSERT) parsetree->hasSubLinks = checkExprHasSubLink(wco->qual); } } } table_close(base_rel, NoLock); return parsetree; } /* * RewriteQuery - * rewrites the query and apply the rules again on the queries rewritten * * rewrite_events is a list of open query-rewrite actions, so we can detect * infinite recursion. * * orig_rt_length is the length of the originating query's rtable, for product * queries created by fireRules(), and 0 otherwise. This is used to skip any * already-processed VALUES RTEs from the original query. */ static List * RewriteQuery(Query *parsetree, List *rewrite_events, int orig_rt_length) { CmdType event = parsetree->commandType; bool instead = false; bool returning = false; bool updatableview = false; Query *qual_product = NULL; List *rewritten = NIL; ListCell *lc1; /* * First, recursively process any insert/update/delete/merge statements in * WITH clauses. (We have to do this first because the WITH clauses may * get copied into rule actions below.) */ foreach(lc1, parsetree->cteList) { CommonTableExpr *cte = lfirst_node(CommonTableExpr, lc1); Query *ctequery = castNode(Query, cte->ctequery); List *newstuff; if (ctequery->commandType == CMD_SELECT) continue; newstuff = RewriteQuery(ctequery, rewrite_events, 0); /* * Currently we can only handle unconditional, single-statement DO * INSTEAD rules correctly; we have to get exactly one non-utility * Query out of the rewrite operation to stuff back into the CTE node. */ if (list_length(newstuff) == 1) { /* Must check it's not a utility command */ ctequery = linitial_node(Query, newstuff); if (!(ctequery->commandType == CMD_SELECT || ctequery->commandType == CMD_UPDATE || ctequery->commandType == CMD_INSERT || ctequery->commandType == CMD_DELETE || ctequery->commandType == CMD_MERGE)) { /* * Currently it could only be NOTIFY; this error message will * need work if we ever allow other utility commands in rules. */ ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("DO INSTEAD NOTIFY rules are not supported for data-modifying statements in WITH"))); } /* WITH queries should never be canSetTag */ Assert(!ctequery->canSetTag); /* Push the single Query back into the CTE node */ cte->ctequery = (Node *) ctequery; } else if (newstuff == NIL) { ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("DO INSTEAD NOTHING rules are not supported for data-modifying statements in WITH"))); } else { ListCell *lc2; /* examine queries to determine which error message to issue */ foreach(lc2, newstuff) { Query *q = (Query *) lfirst(lc2); if (q->querySource == QSRC_QUAL_INSTEAD_RULE) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("conditional DO INSTEAD rules are not supported for data-modifying statements in WITH"))); if (q->querySource == QSRC_NON_INSTEAD_RULE) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("DO ALSO rules are not supported for data-modifying statements in WITH"))); } ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("multi-statement DO INSTEAD rules are not supported for data-modifying statements in WITH"))); } } /* * If the statement is an insert, update, delete, or merge, adjust its * targetlist as needed, and then fire INSERT/UPDATE/DELETE rules on it. * * SELECT rules are handled later when we have all the queries that should * get executed. Also, utilities aren't rewritten at all (do we still * need that check?) */ if (event != CMD_SELECT && event != CMD_UTILITY) { int result_relation; RangeTblEntry *rt_entry; Relation rt_entry_relation; List *locks; int product_orig_rt_length; List *product_queries; bool hasUpdate = false; int values_rte_index = 0; bool defaults_remaining = false; result_relation = parsetree->resultRelation; Assert(result_relation != 0); rt_entry = rt_fetch(result_relation, parsetree->rtable); Assert(rt_entry->rtekind == RTE_RELATION); /* * We can use NoLock here since either the parser or * AcquireRewriteLocks should have locked the rel already. */ rt_entry_relation = table_open(rt_entry->relid, NoLock); /* * Rewrite the targetlist as needed for the command type. */ if (event == CMD_INSERT) { ListCell *lc2; RangeTblEntry *values_rte = NULL; /* * Test if it's a multi-row INSERT ... VALUES (...), (...), ... by * looking for a VALUES RTE in the fromlist. For product queries, * we must ignore any already-processed VALUES RTEs from the * original query. These appear at the start of the rangetable. */ foreach(lc2, parsetree->jointree->fromlist) { RangeTblRef *rtr = (RangeTblRef *) lfirst(lc2); if (IsA(rtr, RangeTblRef) && rtr->rtindex > orig_rt_length) { RangeTblEntry *rte = rt_fetch(rtr->rtindex, parsetree->rtable); if (rte->rtekind == RTE_VALUES) { /* should not find more than one VALUES RTE */ if (values_rte != NULL) elog(ERROR, "more than one VALUES RTE found"); values_rte = rte; values_rte_index = rtr->rtindex; } } } if (values_rte) { Bitmapset *unused_values_attrnos = NULL; /* Process the main targetlist ... */ parsetree->targetList = rewriteTargetListIU(parsetree->targetList, parsetree->commandType, parsetree->override, rt_entry_relation, values_rte, values_rte_index, &unused_values_attrnos); /* ... and the VALUES expression lists */ if (!rewriteValuesRTE(parsetree, values_rte, values_rte_index, rt_entry_relation, unused_values_attrnos)) defaults_remaining = true; } else { /* Process just the main targetlist */ parsetree->targetList = rewriteTargetListIU(parsetree->targetList, parsetree->commandType, parsetree->override, rt_entry_relation, NULL, 0, NULL); } if (parsetree->onConflict && parsetree->onConflict->action == ONCONFLICT_UPDATE) { parsetree->onConflict->onConflictSet = rewriteTargetListIU(parsetree->onConflict->onConflictSet, CMD_UPDATE, parsetree->override, rt_entry_relation, NULL, 0, NULL); } } else if (event == CMD_UPDATE) { Assert(parsetree->override == OVERRIDING_NOT_SET); parsetree->targetList = rewriteTargetListIU(parsetree->targetList, parsetree->commandType, parsetree->override, rt_entry_relation, NULL, 0, NULL); } else if (event == CMD_MERGE) { Assert(parsetree->override == OVERRIDING_NOT_SET); /* * Rewrite each action targetlist separately */ foreach(lc1, parsetree->mergeActionList) { MergeAction *action = (MergeAction *) lfirst(lc1); switch (action->commandType) { case CMD_NOTHING: case CMD_DELETE: /* Nothing to do here */ break; case CMD_UPDATE: case CMD_INSERT: /* * MERGE actions do not permit multi-row INSERTs, so * there is no VALUES RTE to deal with here. */ action->targetList = rewriteTargetListIU(action->targetList, action->commandType, action->override, rt_entry_relation, NULL, 0, NULL); break; default: elog(ERROR, "unrecognized commandType: %d", action->commandType); break; } } } else if (event == CMD_DELETE) { /* Nothing to do here */ } else elog(ERROR, "unrecognized commandType: %d", (int) event); /* * Collect and apply the appropriate rules. */ locks = matchLocks(event, rt_entry_relation, result_relation, parsetree, &hasUpdate); product_orig_rt_length = list_length(parsetree->rtable); product_queries = fireRules(parsetree, result_relation, event, locks, &instead, &returning, &qual_product); /* * If we have a VALUES RTE with any remaining untouched DEFAULT items, * and we got any product queries, finalize the VALUES RTE for each * product query (replacing the remaining DEFAULT items with NULLs). * We don't do this for the original query, because we know that it * must be an auto-insert on a view, and so should use the base * relation's defaults for any remaining DEFAULT items. */ if (defaults_remaining && product_queries != NIL) { ListCell *n; /* * Each product query has its own copy of the VALUES RTE at the * same index in the rangetable, so we must finalize each one. * * Note that if the product query is an INSERT ... SELECT, then * the VALUES RTE will be at the same index in the SELECT part of * the product query rather than the top-level product query * itself. */ foreach(n, product_queries) { Query *pt = (Query *) lfirst(n); RangeTblEntry *values_rte; if (pt->commandType == CMD_INSERT && pt->jointree && IsA(pt->jointree, FromExpr) && list_length(pt->jointree->fromlist) == 1) { Node *jtnode = (Node *) linitial(pt->jointree->fromlist); if (IsA(jtnode, RangeTblRef)) { int rtindex = ((RangeTblRef *) jtnode)->rtindex; RangeTblEntry *src_rte = rt_fetch(rtindex, pt->rtable); if (src_rte->rtekind == RTE_SUBQUERY && src_rte->subquery && IsA(src_rte->subquery, Query) && src_rte->subquery->commandType == CMD_SELECT) pt = src_rte->subquery; } } values_rte = rt_fetch(values_rte_index, pt->rtable); if (values_rte->rtekind != RTE_VALUES) elog(ERROR, "failed to find VALUES RTE in product query"); rewriteValuesRTEToNulls(pt, values_rte); } } /* * If there was no unqualified INSTEAD rule, and the target relation * is a view without any INSTEAD OF triggers, see if the view can be * automatically updated. If so, we perform the necessary query * transformation here and add the resulting query to the * product_queries list, so that it gets recursively rewritten if * necessary. For MERGE, the view must be automatically updatable if * any of the merge actions lack a corresponding INSTEAD OF trigger. * * If the view cannot be automatically updated, we throw an error here * which is OK since the query would fail at runtime anyway. Throwing * the error here is preferable to the executor check since we have * more detailed information available about why the view isn't * updatable. */ if (!instead && rt_entry_relation->rd_rel->relkind == RELKIND_VIEW && !view_has_instead_trigger(rt_entry_relation, event, parsetree->mergeActionList)) { /* * If there were any qualified INSTEAD rules, don't allow the view * to be automatically updated (an unqualified INSTEAD rule or * INSTEAD OF trigger is required). */ if (qual_product != NULL) error_view_not_updatable(rt_entry_relation, parsetree->commandType, parsetree->mergeActionList, gettext_noop("Views with conditional DO INSTEAD rules are not automatically updatable.")); /* * Attempt to rewrite the query to automatically update the view. * This throws an error if the view can't be automatically * updated. */ parsetree = rewriteTargetView(parsetree, rt_entry_relation); /* * At this point product_queries contains any DO ALSO rule * actions. Add the rewritten query before or after those. This * must match the handling the original query would have gotten * below, if we allowed it to be included again. */ if (parsetree->commandType == CMD_INSERT) product_queries = lcons(parsetree, product_queries); else product_queries = lappend(product_queries, parsetree); /* * Set the "instead" flag, as if there had been an unqualified * INSTEAD, to prevent the original query from being included a * second time below. The transformation will have rewritten any * RETURNING list, so we can also set "returning" to forestall * throwing an error below. */ instead = true; returning = true; updatableview = true; } /* * If we got any product queries, recursively rewrite them --- but * first check for recursion! */ if (product_queries != NIL) { ListCell *n; rewrite_event *rev; foreach(n, rewrite_events) { rev = (rewrite_event *) lfirst(n); if (rev->relation == RelationGetRelid(rt_entry_relation) && rev->event == event) ereport(ERROR, (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), errmsg("infinite recursion detected in rules for relation \"%s\"", RelationGetRelationName(rt_entry_relation)))); } rev = (rewrite_event *) palloc(sizeof(rewrite_event)); rev->relation = RelationGetRelid(rt_entry_relation); rev->event = event; rewrite_events = lappend(rewrite_events, rev); foreach(n, product_queries) { Query *pt = (Query *) lfirst(n); List *newstuff; /* * For an updatable view, pt might be the rewritten version of * the original query, in which case we pass on orig_rt_length * to finish processing any VALUES RTE it contained. * * Otherwise, we have a product query created by fireRules(). * Any VALUES RTEs from the original query have been fully * processed, and must be skipped when we recurse. */ newstuff = RewriteQuery(pt, rewrite_events, pt == parsetree ? orig_rt_length : product_orig_rt_length); rewritten = list_concat(rewritten, newstuff); } rewrite_events = list_delete_last(rewrite_events); } /* * If there is an INSTEAD, and the original query has a RETURNING, we * have to have found a RETURNING in the rule(s), else fail. (Because * DefineQueryRewrite only allows RETURNING in unconditional INSTEAD * rules, there's no need to worry whether the substituted RETURNING * will actually be executed --- it must be.) */ if ((instead || qual_product != NULL) && parsetree->returningList && !returning) { switch (event) { case CMD_INSERT: ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot perform INSERT RETURNING on relation \"%s\"", RelationGetRelationName(rt_entry_relation)), errhint("You need an unconditional ON INSERT DO INSTEAD rule with a RETURNING clause."))); break; case CMD_UPDATE: ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot perform UPDATE RETURNING on relation \"%s\"", RelationGetRelationName(rt_entry_relation)), errhint("You need an unconditional ON UPDATE DO INSTEAD rule with a RETURNING clause."))); break; case CMD_DELETE: ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot perform DELETE RETURNING on relation \"%s\"", RelationGetRelationName(rt_entry_relation)), errhint("You need an unconditional ON DELETE DO INSTEAD rule with a RETURNING clause."))); break; default: elog(ERROR, "unrecognized commandType: %d", (int) event); break; } } /* * Updatable views are supported by ON CONFLICT, so don't prevent that * case from proceeding */ if (parsetree->onConflict && (product_queries != NIL || hasUpdate) && !updatableview) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("INSERT with ON CONFLICT clause cannot be used with table that has INSERT or UPDATE rules"))); table_close(rt_entry_relation, NoLock); } /* * For INSERTs, the original query is done first; for UPDATE/DELETE, it is * done last. This is needed because update and delete rule actions might * not do anything if they are invoked after the update or delete is * performed. The command counter increment between the query executions * makes the deleted (and maybe the updated) tuples disappear so the scans * for them in the rule actions cannot find them. * * If we found any unqualified INSTEAD, the original query is not done at * all, in any form. Otherwise, we add the modified form if qualified * INSTEADs were found, else the unmodified form. */ if (!instead) { if (parsetree->commandType == CMD_INSERT) { if (qual_product != NULL) rewritten = lcons(qual_product, rewritten); else rewritten = lcons(parsetree, rewritten); } else { if (qual_product != NULL) rewritten = lappend(rewritten, qual_product); else rewritten = lappend(rewritten, parsetree); } } /* * If the original query has a CTE list, and we generated more than one * non-utility result query, we have to fail because we'll have copied the * CTE list into each result query. That would break the expectation of * single evaluation of CTEs. This could possibly be fixed by * restructuring so that a CTE list can be shared across multiple Query * and PlannableStatement nodes. */ if (parsetree->cteList != NIL) { int qcount = 0; foreach(lc1, rewritten) { Query *q = (Query *) lfirst(lc1); if (q->commandType != CMD_UTILITY) qcount++; } if (qcount > 1) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("WITH cannot be used in a query that is rewritten by rules into multiple queries"))); } return rewritten; } /* * Expand virtual generated columns * * If the table contains virtual generated columns, build a target list * containing the expanded expressions and use ReplaceVarsFromTargetList() to * do the replacements. * * Vars matching rt_index at the current query level are replaced by the * virtual generated column expressions from rel, if there are any. * * The caller must also provide rte, the RTE describing the target relation, * in order to handle any whole-row Vars referencing the target, and * result_relation, the index of the result relation, if this is part of an * INSERT/UPDATE/DELETE/MERGE query. */ static Node * expand_generated_columns_internal(Node *node, Relation rel, int rt_index, RangeTblEntry *rte, int result_relation) { TupleDesc tupdesc; tupdesc = RelationGetDescr(rel); if (tupdesc->constr && tupdesc->constr->has_generated_virtual) { List *tlist = NIL; for (int i = 0; i < tupdesc->natts; i++) { Form_pg_attribute attr = TupleDescAttr(tupdesc, i); if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) { Node *defexpr; TargetEntry *te; defexpr = build_generation_expression(rel, i + 1); ChangeVarNodes(defexpr, 1, rt_index, 0); te = makeTargetEntry((Expr *) defexpr, i + 1, 0, false); tlist = lappend(tlist, te); } } Assert(list_length(tlist) > 0); node = ReplaceVarsFromTargetList(node, rt_index, 0, rte, tlist, result_relation, REPLACEVARS_CHANGE_VARNO, rt_index, NULL); } return node; } /* * Expand virtual generated columns in an expression * * This is for expressions that are not part of a query, such as default * expressions or index predicates. The rt_index is usually 1. */ Node * expand_generated_columns_in_expr(Node *node, Relation rel, int rt_index) { TupleDesc tupdesc = RelationGetDescr(rel); if (tupdesc->constr && tupdesc->constr->has_generated_virtual) { RangeTblEntry *rte; rte = makeNode(RangeTblEntry); /* eref needs to be set, but the actual name doesn't matter */ rte->eref = makeAlias(RelationGetRelationName(rel), NIL); rte->rtekind = RTE_RELATION; rte->relid = RelationGetRelid(rel); node = expand_generated_columns_internal(node, rel, rt_index, rte, 0); } return node; } /* * Build the generation expression for the virtual generated column. * * Error out if there is no generation expression found for the given column. */ Node * build_generation_expression(Relation rel, int attrno) { TupleDesc rd_att = RelationGetDescr(rel); Form_pg_attribute att_tup = TupleDescAttr(rd_att, attrno - 1); Node *defexpr; Oid attcollid; Assert(rd_att->constr && rd_att->constr->has_generated_virtual); Assert(att_tup->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL); defexpr = build_column_default(rel, attrno); if (defexpr == NULL) elog(ERROR, "no generation expression found for column number %d of table \"%s\"", attrno, RelationGetRelationName(rel)); /* * If the column definition has a collation and it is different from the * collation of the generation expression, put a COLLATE clause around the * expression. */ attcollid = att_tup->attcollation; if (attcollid && attcollid != exprCollation(defexpr)) { CollateExpr *ce = makeNode(CollateExpr); ce->arg = (Expr *) defexpr; ce->collOid = attcollid; ce->location = -1; defexpr = (Node *) ce; } return defexpr; } /* * QueryRewrite - * Primary entry point to the query rewriter. * Rewrite one query via query rewrite system, possibly returning 0 * or many queries. * * NOTE: the parsetree must either have come straight from the parser, * or have been scanned by AcquireRewriteLocks to acquire suitable locks. */ List * QueryRewrite(Query *parsetree) { int64 input_query_id = parsetree->queryId; List *querylist; List *results; ListCell *l; CmdType origCmdType; bool foundOriginalQuery; Query *lastInstead; /* * This function is only applied to top-level original queries */ Assert(parsetree->querySource == QSRC_ORIGINAL); Assert(parsetree->canSetTag); /* * Step 1 * * Apply all non-SELECT rules possibly getting 0 or many queries */ querylist = RewriteQuery(parsetree, NIL, 0); /* * Step 2 * * Apply all the RIR rules on each query * * This is also a handy place to mark each query with the original queryId */ results = NIL; foreach(l, querylist) { Query *query = (Query *) lfirst(l); query = fireRIRrules(query, NIL); query->queryId = input_query_id; results = lappend(results, query); } /* * Step 3 * * Determine which, if any, of the resulting queries is supposed to set * the command-result tag; and update the canSetTag fields accordingly. * * If the original query is still in the list, it sets the command tag. * Otherwise, the last INSTEAD query of the same kind as the original is * allowed to set the tag. (Note these rules can leave us with no query * setting the tag. The tcop code has to cope with this by setting up a * default tag based on the original un-rewritten query.) * * The Asserts verify that at most one query in the result list is marked * canSetTag. If we aren't checking asserts, we can fall out of the loop * as soon as we find the original query. */ origCmdType = parsetree->commandType; foundOriginalQuery = false; lastInstead = NULL; foreach(l, results) { Query *query = (Query *) lfirst(l); if (query->querySource == QSRC_ORIGINAL) { Assert(query->canSetTag); Assert(!foundOriginalQuery); foundOriginalQuery = true; #ifndef USE_ASSERT_CHECKING break; #endif } else { Assert(!query->canSetTag); if (query->commandType == origCmdType && (query->querySource == QSRC_INSTEAD_RULE || query->querySource == QSRC_QUAL_INSTEAD_RULE)) lastInstead = query; } } if (!foundOriginalQuery && lastInstead != NULL) lastInstead->canSetTag = true; return results; }