diff options
Diffstat (limited to 'src/backend/rewrite/rewriteHandler.c')
| -rw-r--r-- | src/backend/rewrite/rewriteHandler.c | 321 |
1 files changed, 156 insertions, 165 deletions
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c index 1c58ccd7ca3..3513cf67c4b 100644 --- a/src/backend/rewrite/rewriteHandler.c +++ b/src/backend/rewrite/rewriteHandler.c @@ -7,7 +7,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.157 2005/08/01 20:31:10 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.158 2005/10/15 02:49:24 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -53,7 +53,7 @@ static TargetEntry *process_matched_tle(TargetEntry *src_tle, const char *attrName); static Node *get_assignment_input(Node *node); static void markQueryForLocking(Query *qry, bool forUpdate, bool noWait, - bool skipOldNew); + bool skipOldNew); static List *matchLocks(CmdType event, RuleLock *rulelocks, int varno, Query *parsetree); static Query *fireRIRrules(Query *parsetree, List *activeRIRs); @@ -115,17 +115,17 @@ AcquireRewriteLocks(Query *parsetree) 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 and planner against schema changes mid-query. + * Grab the appropriate lock type for the relation, and do not + * release it until end of transaction. This protects the + * rewriter and planner against schema changes mid-query. * - * If the relation is the query's result relation, then we - * need RowExclusiveLock. Otherwise, check to see if the - * relation is accessed FOR UPDATE/SHARE or not. We can't - * just grab AccessShareLock because then the executor - * would be trying to upgrade the lock, leading to possible - * deadlocks. + * If the relation is the query's result relation, then we need + * RowExclusiveLock. Otherwise, check to see if the relation + * is accessed FOR UPDATE/SHARE or not. We can't just grab + * AccessShareLock because then the executor would be trying + * to upgrade the lock, leading to possible deadlocks. */ if (rt_index == parsetree->resultRelation) lockmode = RowExclusiveLock; @@ -139,14 +139,15 @@ AcquireRewriteLocks(Query *parsetree) 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 Consts. + * Scan the join's alias var list to see if any columns have + * been dropped, and if so replace those Vars with NULL + * Consts. * - * Since a join has only two inputs, we can expect to - * see multiple references to the same input RTE; optimize - * away multiple fetches. + * 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; @@ -159,19 +160,19 @@ AcquireRewriteLocks(Query *parsetree) * 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 constant already? But that's OK too.) + * the join clause. (Conceivably it could also be a NULL + * constant already? But that's OK too.) */ if (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.) + * 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) @@ -200,6 +201,7 @@ AcquireRewriteLocks(Query *parsetree) break; case RTE_SUBQUERY: + /* * The subquery RTE itself is all right, but we have to * recurse to process the represented subquery. @@ -214,8 +216,8 @@ AcquireRewriteLocks(Query *parsetree) } /* - * Recurse into sublink subqueries, too. But we already did the ones - * in the rtable. + * Recurse into sublink subqueries, too. But we already did the ones in + * the rtable. */ if (parsetree->hasSubLinks) query_tree_walker(parsetree, acquireLocksOnSubLinks, NULL, @@ -266,8 +268,8 @@ rewriteRuleAction(Query *parsetree, Query **sub_action_ptr; /* - * Make modifiable copies of rule action and qual (what we're passed - * are the stored versions in the relcache; don't touch 'em!). + * 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 = (Query *) copyObject(rule_action); rule_qual = (Node *) copyObject(rule_qual); @@ -283,12 +285,12 @@ rewriteRuleAction(Query *parsetree, 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. + * 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!). + * 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); @@ -303,50 +305,47 @@ rewriteRuleAction(Query *parsetree, /* * 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 for two reasons: + * action. Some of the entries may be unused after we finish rewriting, + * but we leave them all in place for two reasons: * - * We'd have a much harder job to adjust the query's varnos if we - * selectively removed RT entries. + * We'd have a much harder job to adjust the query's varnos if we selectively + * removed RT entries. * - * If the rule is INSTEAD, then the original query won't be executed at - * all, and so its rtable must be preserved so that the executor will - * do the correct permissions checks on it. + * If the rule is INSTEAD, then the original query won't be executed at all, + * and so its rtable must be preserved so that the executor will do the + * correct permissions checks on it. * * RT entries that are not referenced in the completed jointree will be - * ignored by the planner, so they do not affect query semantics. But - * any permissions checks specified in them will be applied during - * executor startup (see ExecCheckRTEPerms()). 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. + * ignored by the planner, so they do not affect query semantics. But any + * permissions checks specified in them will be applied during executor + * startup (see ExecCheckRTEPerms()). 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 on its copied - * RT entries will be redundant with those done during execution of - * the original query, but we don't bother to treat that case - * differently. + * When a rule is not INSTEAD, the permissions checks done on its copied RT + * 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, we must ensure - * that rule action's rtable is separate and shares no substructure - * with the main rtable. Hence do a deep copy here. + * NOTE: because planner will destructively alter rtable, we must ensure that + * rule action's rtable is separate and shares no substructure with the + * main rtable. Hence do a deep copy here. */ sub_action->rtable = list_concat((List *) copyObject(parsetree->rtable), sub_action->rtable); /* * 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. + * 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. + * As above, the action's jointree must not share substructure with the main + * parsetree's. */ if (sub_action->commandType != CMD_UTILITY) { @@ -357,15 +356,15 @@ rewriteRuleAction(Query *parsetree, 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)); + 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 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, @@ -378,9 +377,9 @@ rewriteRuleAction(Query *parsetree, } /* - * 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 + * 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); @@ -390,9 +389,9 @@ rewriteRuleAction(Query *parsetree, * Rewrite new.attribute w/ right hand side of target-list entry for * appropriate field name in insert/update. * - * KLUGE ALERT: since ResolveNew 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. + * KLUGE ALERT: since ResolveNew 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) @@ -440,8 +439,7 @@ adjustJoinTreeList(Query *parsetree, bool removert, int rt_index) newjointree = list_delete_ptr(newjointree, rtr); /* - * foreach is safe because we exit loop after - * list_delete... + * foreach is safe because we exit loop after list_delete... */ break; } @@ -494,13 +492,13 @@ rewriteTargetList(Query *parsetree, Relation target_relation) ListCell *temp; /* - * 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. + * 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. + * 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 *)); @@ -531,11 +529,11 @@ rewriteTargetList(Query *parsetree, Relation target_relation) else { /* - * Copy all resjunk tlist entries to junk_tlist, and - * assign them resnos above the last real resno. + * 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 + * Typical junk entries include ORDER BY or GROUP BY expressions (are + * these actually possible in an INSERT or UPDATE?), system * attribute references, etc. */ @@ -561,9 +559,9 @@ rewriteTargetList(Query *parsetree, Relation target_relation) 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. + * 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. */ if ((new_tle == NULL && commandType == CMD_INSERT) || (new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault))) @@ -573,12 +571,11 @@ rewriteTargetList(Query *parsetree, Relation target_relation) 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 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) { @@ -640,8 +637,7 @@ process_matched_tle(TargetEntry *src_tle, if (prior_tle == NULL) { /* - * Normal case where this is the first assignment to the - * attribute. + * Normal case where this is the first assignment to the attribute. */ return src_tle; } @@ -682,8 +678,7 @@ process_matched_tle(TargetEntry *src_tle, attrName))); /* - * Prior TLE could be a nest of assignments if we do this more than - * once. + * Prior TLE could be a nest of assignments if we do this more than once. */ priorbottom = prior_input; for (;;) @@ -713,10 +708,10 @@ process_matched_tle(TargetEntry *src_tle, memcpy(fstore, prior_expr, sizeof(FieldStore)); fstore->newvals = list_concat(list_copy(((FieldStore *) prior_expr)->newvals), - list_copy(((FieldStore *) src_expr)->newvals)); + list_copy(((FieldStore *) src_expr)->newvals)); fstore->fieldnums = list_concat(list_copy(((FieldStore *) prior_expr)->fieldnums), - list_copy(((FieldStore *) src_expr)->fieldnums)); + list_copy(((FieldStore *) src_expr)->fieldnums)); } else { @@ -809,8 +804,7 @@ build_column_default(Relation rel, int attrno) if (expr == NULL) { /* - * No per-column default, so look for a default for the type - * itself. + * No per-column default, so look for a default for the type itself. */ expr = get_typdefault(atttype); } @@ -821,8 +815,8 @@ build_column_default(Relation rel, int attrno) /* * 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 + * involving domain defaults where it might not be true. This should match + * the parser's processing of non-defaulted expressions --- see * updateTargetListEntry(). */ exprtype = exprType(expr); @@ -840,7 +834,7 @@ build_column_default(Relation rel, int attrno) NameStr(att_tup->attname), format_type_be(atttype), format_type_be(exprtype)), - errhint("You will need to rewrite or cast the expression."))); + errhint("You will need to rewrite or cast the expression."))); return expr; } @@ -913,8 +907,8 @@ ApplyRetrieveRule(Query *parsetree, elog(ERROR, "cannot handle per-attribute ON SELECT rule"); /* - * Make a modifiable copy of the view query, and acquire needed locks - * on the relations it mentions. + * Make a modifiable copy of the view query, and acquire needed locks on + * the relations it mentions. */ rule_action = copyObject(linitial(rule->actions)); @@ -926,8 +920,8 @@ ApplyRetrieveRule(Query *parsetree, rule_action = fireRIRrules(rule_action, activeRIRs); /* - * VIEWs are really easy --- just plug the view query in as a - * subselect, replacing the relation's original RTE. + * VIEWs are really easy --- just plug the view query in as a subselect, + * replacing the relation's original RTE. */ rte = rt_fetch(rt_index, parsetree->rtable); @@ -937,8 +931,8 @@ ApplyRetrieveRule(Query *parsetree, rte->inh = false; /* must not be set for a subquery */ /* - * We move the view's permission check data down to its rangetable. - * The checks will actually be done against the *OLD* entry therein. + * We move the view's permission check data down to its rangetable. The + * checks will actually be done against the *OLD* entry therein. */ subrte = rt_fetch(PRS2_OLD_VARNO, rule_action->rtable); Assert(subrte->relid == relation->rd_id); @@ -954,9 +948,9 @@ ApplyRetrieveRule(Query *parsetree, if (list_member_int(parsetree->rowMarks, rt_index)) { /* - * Remove the view from the list of rels that will actually be - * marked FOR UPDATE/SHARE by the executor. It will still be access- - * checked for write access, though. + * Remove the view from the list of rels that will actually be marked + * FOR UPDATE/SHARE by the executor. It will still be access- checked + * for write access, though. */ parsetree->rowMarks = list_delete_int(parsetree->rowMarks, rt_index); @@ -989,7 +983,7 @@ markQueryForLocking(Query *qry, bool forUpdate, bool noWait, bool skipOldNew) if (forUpdate != qry->forUpdate) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("cannot use both FOR UPDATE and FOR SHARE in one query"))); + errmsg("cannot use both FOR UPDATE and FOR SHARE in one query"))); if (noWait != qry->rowNoWait) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), @@ -1052,8 +1046,8 @@ fireRIRonSubLink(Node *node, List *activeRIRs) } /* - * Do NOT recurse into Query nodes, because fireRIRrules already - * processed subselects of subselects for us. + * Do NOT recurse into Query nodes, because fireRIRrules already processed + * subselects of subselects for us. */ return expression_tree_walker(node, fireRIRonSubLink, (void *) activeRIRs); @@ -1070,8 +1064,8 @@ fireRIRrules(Query *parsetree, List *activeRIRs) int rt_index; /* - * don't try to convert this into a foreach loop, because rtable list - * can get changed each time through... + * 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)) @@ -1088,8 +1082,8 @@ fireRIRrules(Query *parsetree, List *activeRIRs) 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 + * 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) @@ -1108,8 +1102,8 @@ fireRIRrules(Query *parsetree, List *activeRIRs) * 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. + * 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)) @@ -1181,8 +1175,8 @@ fireRIRrules(Query *parsetree, List *activeRIRs) } /* - * Recurse into sublink subqueries, too. But we already did the ones - * in the rtable. + * Recurse into sublink subqueries, too. But we already did the ones in + * the rtable. */ if (parsetree->hasSubLinks) query_tree_walker(parsetree, fireRIRonSubLink, (void *) activeRIRs, @@ -1217,8 +1211,8 @@ CopyAndAddInvertedQual(Query *parsetree, /* * 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.) + * rewriteRuleAction, but not entirely ... consider restructuring so that + * we only need to process the qual this way once.) */ (void) acquireLocksOnSubLinks(new_qual, NULL); @@ -1302,13 +1296,13 @@ fireRules(Query *parsetree, 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 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. @@ -1364,9 +1358,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events) /* * If the statement is an update, insert or delete - fire 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?) + * 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) { @@ -1387,10 +1381,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events) rt_entry_relation = heap_open(rt_entry->relid, NoLock); /* - * If it's an INSERT or UPDATE, rewrite the targetlist into - * standard form. This will be needed by the planner anyway, and - * doing it now ensures that any references to NEW.field will - * behave sanely. + * If it's an INSERT or UPDATE, rewrite the targetlist into standard + * form. This will be needed by the planner anyway, and doing it now + * ensures that any references to NEW.field will behave sanely. */ if (event == CMD_INSERT || event == CMD_UPDATE) rewriteTargetList(parsetree, rt_entry_relation); @@ -1413,8 +1406,8 @@ RewriteQuery(Query *parsetree, List *rewrite_events) &qual_product); /* - * If we got any product queries, recursively rewrite them --- - * but first check for recursion! + * If we got any product queries, recursively rewrite them --- but + * first check for recursion! */ if (product_queries != NIL) { @@ -1427,9 +1420,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events) 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)))); + (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)); @@ -1454,13 +1447,12 @@ RewriteQuery(Query *parsetree, List *rewrite_events) } /* - * 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. + * 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 @@ -1569,19 +1561,18 @@ QueryRewrite(Query *parsetree) /* * Step 3 * - * Determine which, if any, of the resulting queries is supposed to set - * the command-result tag; and update the canSetTag fields - * accordingly. + * 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.) + * 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. + * 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; |