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1308 lines
37 KiB
C
1308 lines
37 KiB
C
/*-------------------------------------------------------------------------
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*
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* rewriteHandler.c
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* Primary module of query rewriter.
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*
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* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.121 2003/06/25 04:19:24 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/heapam.h"
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#include "catalog/pg_operator.h"
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#include "catalog/pg_type.h"
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#include "miscadmin.h"
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#include "nodes/makefuncs.h"
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#include "optimizer/clauses.h"
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#include "optimizer/prep.h"
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#include "optimizer/var.h"
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#include "parser/analyze.h"
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#include "parser/parse_coerce.h"
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#include "parser/parse_expr.h"
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#include "parser/parse_oper.h"
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#include "parser/parse_type.h"
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#include "parser/parsetree.h"
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#include "rewrite/rewriteHandler.h"
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#include "rewrite/rewriteManip.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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/* We use a list of these to detect recursion in RewriteQuery */
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typedef struct rewrite_event {
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Oid relation; /* OID of relation having rules */
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CmdType event; /* type of rule being fired */
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} rewrite_event;
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static Query *rewriteRuleAction(Query *parsetree,
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Query *rule_action,
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Node *rule_qual,
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int rt_index,
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CmdType event);
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static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
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static void rewriteTargetList(Query *parsetree, Relation target_relation);
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static TargetEntry *process_matched_tle(TargetEntry *src_tle,
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TargetEntry *prior_tle);
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static void markQueryForUpdate(Query *qry, bool skipOldNew);
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static List *matchLocks(CmdType event, RuleLock *rulelocks,
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int varno, Query *parsetree);
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static Query *fireRIRrules(Query *parsetree, List *activeRIRs);
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/*
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* rewriteRuleAction -
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* Rewrite the rule action with appropriate qualifiers (taken from
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* the triggering query).
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*/
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static Query *
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rewriteRuleAction(Query *parsetree,
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Query *rule_action,
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Node *rule_qual,
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int rt_index,
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CmdType event)
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{
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int current_varno,
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new_varno;
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List *main_rtable;
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int rt_length;
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Query *sub_action;
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Query **sub_action_ptr;
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List *rt;
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/*
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* Make modifiable copies of rule action and qual (what we're passed
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* are the stored versions in the relcache; don't touch 'em!).
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*/
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rule_action = (Query *) copyObject(rule_action);
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rule_qual = (Node *) copyObject(rule_qual);
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current_varno = rt_index;
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rt_length = length(parsetree->rtable);
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new_varno = PRS2_NEW_VARNO + rt_length;
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/*
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* Adjust rule action and qual to offset its varnos, so that we can
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* merge its rtable with the main parsetree's rtable.
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*
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* If the rule action is an INSERT...SELECT, the OLD/NEW rtable entries
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* will be in the SELECT part, and we have to modify that rather than
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* the top-level INSERT (kluge!).
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*/
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sub_action = getInsertSelectQuery(rule_action, &sub_action_ptr);
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OffsetVarNodes((Node *) sub_action, rt_length, 0);
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OffsetVarNodes(rule_qual, rt_length, 0);
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/* but references to *OLD* should point at original rt_index */
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ChangeVarNodes((Node *) sub_action,
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PRS2_OLD_VARNO + rt_length, rt_index, 0);
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ChangeVarNodes(rule_qual,
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PRS2_OLD_VARNO + rt_length, rt_index, 0);
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/*
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* Generate expanded rtable consisting of main parsetree's rtable plus
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* rule action's rtable; this becomes the complete rtable for the rule
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* action. Some of the entries may be unused after we finish
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* rewriting, but if we tried to remove them we'd have a much
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* harder job to adjust RT indexes in the query's Vars. It's OK to
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* have unused RT entries, since planner will ignore them.
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*
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* NOTE: because planner will destructively alter rtable, we must ensure
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* that rule action's rtable is separate and shares no substructure
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* with the main rtable. Hence do a deep copy here.
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*
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* Also, we must disable write-access checking in all the RT entries
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* copied from the main query. This is safe since in fact the rule action
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* won't write on them, and it's necessary because the rule action may
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* have a different commandType than the main query, causing
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* ExecCheckRTEPerms() to make an inappropriate check. The read-access
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* checks can be left enabled, although they're probably redundant.
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*/
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main_rtable = (List *) copyObject(parsetree->rtable);
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foreach(rt, main_rtable)
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{
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RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);
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rte->checkForWrite = false;
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}
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sub_action->rtable = nconc(main_rtable, sub_action->rtable);
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/*
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* Each rule action's jointree should be the main parsetree's jointree
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* plus that rule's jointree, but usually *without* the original
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* rtindex that we're replacing (if present, which it won't be for
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* INSERT). Note that if the rule action refers to OLD, its jointree
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* will add a reference to rt_index. If the rule action doesn't refer
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* to OLD, but either the rule_qual or the user query quals do, then
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* we need to keep the original rtindex in the jointree to provide
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* data for the quals. We don't want the original rtindex to be
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* joined twice, however, so avoid keeping it if the rule action
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* mentions it.
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*
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* As above, the action's jointree must not share substructure with the
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* main parsetree's.
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*/
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if (sub_action->jointree != NULL)
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{
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bool keeporig;
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List *newjointree;
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keeporig = (!rangeTableEntry_used((Node *) sub_action->jointree,
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rt_index, 0)) &&
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(rangeTableEntry_used(rule_qual, rt_index, 0) ||
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rangeTableEntry_used(parsetree->jointree->quals, rt_index, 0));
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newjointree = adjustJoinTreeList(parsetree, !keeporig, rt_index);
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sub_action->jointree->fromlist =
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nconc(newjointree, sub_action->jointree->fromlist);
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}
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/*
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* We copy the qualifications of the parsetree to the action and vice
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* versa. So force hasSubLinks if one of them has it. If this is not
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* right, the flag will get cleared later, but we mustn't risk having
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* it not set when it needs to be. (XXX this should probably be
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* handled by AddQual and friends, not here...)
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*/
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if (parsetree->hasSubLinks)
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sub_action->hasSubLinks = TRUE;
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else if (sub_action->hasSubLinks)
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parsetree->hasSubLinks = TRUE;
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/*
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* Event Qualification forces copying of parsetree and splitting into
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* two queries one w/rule_qual, one w/NOT rule_qual. Also add user
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* query qual onto rule action
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*/
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AddQual(sub_action, rule_qual);
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AddQual(sub_action, parsetree->jointree->quals);
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/*
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* Rewrite new.attribute w/ right hand side of target-list entry for
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* appropriate field name in insert/update.
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*
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* KLUGE ALERT: since ResolveNew returns a mutated copy, we can't just
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* apply it to sub_action; we have to remember to update the sublink
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* inside rule_action, too.
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*/
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if (event == CMD_INSERT || event == CMD_UPDATE)
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{
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sub_action = (Query *) ResolveNew((Node *) sub_action,
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new_varno,
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0,
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parsetree->targetList,
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event,
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current_varno);
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if (sub_action_ptr)
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*sub_action_ptr = sub_action;
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else
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rule_action = sub_action;
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}
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return rule_action;
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}
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/*
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* Copy the query's jointree list, and optionally attempt to remove any
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* occurrence of the given rt_index as a top-level join item (we do not look
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* for it within join items; this is OK because we are only expecting to find
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* it as an UPDATE or DELETE target relation, which will be at the top level
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* of the join). Returns modified jointree list --- this is a separate copy
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* sharing no nodes with the original.
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*/
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static List *
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adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
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{
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List *newjointree = copyObject(parsetree->jointree->fromlist);
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List *jjt;
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if (removert)
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{
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foreach(jjt, newjointree)
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{
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RangeTblRef *rtr = lfirst(jjt);
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if (IsA(rtr, RangeTblRef) &&
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rtr->rtindex == rt_index)
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{
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newjointree = lremove(rtr, newjointree);
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/* foreach is safe because we exit loop after lremove... */
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break;
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}
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}
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}
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return newjointree;
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}
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/*
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* rewriteTargetList - rewrite INSERT/UPDATE targetlist into standard form
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*
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* This has the following responsibilities:
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*
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* 1. For an INSERT, add tlist entries to compute default values for any
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* attributes that have defaults and are not assigned to in the given tlist.
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* (We do not insert anything for default-less attributes, however. The
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* planner will later insert NULLs for them, but there's no reason to slow
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* down rewriter processing with extra tlist nodes.)
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*
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* 2. Merge multiple entries for the same target attribute, or declare error
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* if we can't. Presently, multiple entries are only allowed for UPDATE of
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* an array field, for example "UPDATE table SET foo[2] = 42, foo[4] = 43".
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* We can merge such operations into a single assignment op. Essentially,
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* the expression we want to produce in this case is like
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* foo = array_set(array_set(foo, 2, 42), 4, 43)
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*
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* 3. Sort the tlist into standard order: non-junk fields in order by resno,
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* then junk fields (these in no particular order).
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*
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* We must do items 1 and 2 before firing rewrite rules, else rewritten
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* references to NEW.foo will produce wrong or incomplete results. Item 3
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* is not needed for rewriting, but will be needed by the planner, and we
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* can do it essentially for free while handling items 1 and 2.
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*/
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static void
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rewriteTargetList(Query *parsetree, Relation target_relation)
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{
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CmdType commandType = parsetree->commandType;
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List *tlist = parsetree->targetList;
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List *new_tlist = NIL;
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int attrno,
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numattrs;
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List *temp;
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/*
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* Scan the tuple description in the relation's relcache entry to make
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* sure we have all the user attributes in the right order.
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*/
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numattrs = RelationGetNumberOfAttributes(target_relation);
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for (attrno = 1; attrno <= numattrs; attrno++)
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{
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Form_pg_attribute att_tup = target_relation->rd_att->attrs[attrno - 1];
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TargetEntry *new_tle = NULL;
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/* We can ignore deleted attributes */
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if (att_tup->attisdropped)
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continue;
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/*
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* Look for targetlist entries matching this attr. We match by
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* resno, but the resname should match too.
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*
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* Junk attributes are not candidates to be matched.
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*/
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foreach(temp, tlist)
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{
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TargetEntry *old_tle = (TargetEntry *) lfirst(temp);
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Resdom *resdom = old_tle->resdom;
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if (!resdom->resjunk && resdom->resno == attrno)
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{
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Assert(strcmp(resdom->resname,
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NameStr(att_tup->attname)) == 0);
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if (old_tle->expr != NULL && IsA(old_tle->expr, SetToDefault))
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{
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/* Set to the default value of the column, as requested */
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Node *new_expr;
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new_expr = build_column_default(target_relation, attrno);
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new_tle = makeTargetEntry(makeResdom(attrno,
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att_tup->atttypid,
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att_tup->atttypmod,
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pstrdup(NameStr(att_tup->attname)),
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false),
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(Expr *) new_expr);
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}
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else
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/* Normal Case */
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new_tle = process_matched_tle(old_tle, new_tle);
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/* keep scanning to detect multiple assignments to attr */
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}
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}
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if (new_tle == NULL && commandType == CMD_INSERT)
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{
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/*
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* Didn't find a matching tlist entry; if it's an INSERT, look
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* for a default value, and add a tlist entry computing the
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* default if we find one.
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*/
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Node *new_expr;
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new_expr = build_column_default(target_relation, attrno);
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if (new_expr)
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new_tle = makeTargetEntry(makeResdom(attrno,
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att_tup->atttypid,
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att_tup->atttypmod,
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pstrdup(NameStr(att_tup->attname)),
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false),
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(Expr *) new_expr);
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}
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if (new_tle)
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new_tlist = lappend(new_tlist, new_tle);
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}
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/*
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* Copy all resjunk tlist entries to the end of the new tlist, and
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* assign them resnos above the last real resno.
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*
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* Typical junk entries include ORDER BY or GROUP BY expressions (are
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* these actually possible in an INSERT or UPDATE?), system attribute
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* references, etc.
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*/
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foreach(temp, tlist)
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{
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TargetEntry *old_tle = (TargetEntry *) lfirst(temp);
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Resdom *resdom = old_tle->resdom;
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if (resdom->resjunk)
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{
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/* Get the resno right, but don't copy unnecessarily */
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if (resdom->resno != attrno)
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{
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resdom = (Resdom *) copyObject((Node *) resdom);
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resdom->resno = attrno;
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old_tle = makeTargetEntry(resdom, old_tle->expr);
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}
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new_tlist = lappend(new_tlist, old_tle);
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attrno++;
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}
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else
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{
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/* Let's just make sure we processed all the non-junk items */
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if (resdom->resno < 1 || resdom->resno > numattrs)
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elog(ERROR, "rewriteTargetList: bogus resno %d in targetlist",
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resdom->resno);
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}
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}
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parsetree->targetList = new_tlist;
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}
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/*
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* Convert a matched TLE from the original tlist into a correct new TLE.
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*
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* This routine detects and handles multiple assignments to the same target
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* attribute.
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*/
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static TargetEntry *
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process_matched_tle(TargetEntry *src_tle,
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TargetEntry *prior_tle)
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{
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Resdom *resdom = src_tle->resdom;
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Node *priorbottom;
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ArrayRef *newexpr;
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if (prior_tle == NULL)
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{
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/*
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* Normal case where this is the first assignment to the
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* attribute.
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*/
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return src_tle;
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}
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/*
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* Multiple assignments to same attribute. Allow only if all are
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* array-assign operators with same bottom array object.
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*/
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if (src_tle->expr == NULL || !IsA(src_tle->expr, ArrayRef) ||
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((ArrayRef *) src_tle->expr)->refassgnexpr == NULL ||
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prior_tle->expr == NULL || !IsA(prior_tle->expr, ArrayRef) ||
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((ArrayRef *) prior_tle->expr)->refassgnexpr == NULL ||
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((ArrayRef *) src_tle->expr)->refrestype !=
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((ArrayRef *) prior_tle->expr)->refrestype)
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elog(ERROR, "Multiple assignments to same attribute \"%s\"",
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resdom->resname);
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/*
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* Prior TLE could be a nest of ArrayRefs if we do this more than
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* once.
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*/
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priorbottom = (Node *) ((ArrayRef *) prior_tle->expr)->refexpr;
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while (priorbottom != NULL && IsA(priorbottom, ArrayRef) &&
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((ArrayRef *) priorbottom)->refassgnexpr != NULL)
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priorbottom = (Node *) ((ArrayRef *) priorbottom)->refexpr;
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if (!equal(priorbottom, ((ArrayRef *) src_tle->expr)->refexpr))
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elog(ERROR, "Multiple assignments to same attribute \"%s\"",
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resdom->resname);
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/*
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* Looks OK to nest 'em.
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*/
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newexpr = makeNode(ArrayRef);
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memcpy(newexpr, src_tle->expr, sizeof(ArrayRef));
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newexpr->refexpr = prior_tle->expr;
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return makeTargetEntry(resdom, (Expr *) newexpr);
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}
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/*
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* Make an expression tree for the default value for a column.
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*
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* If there is no default, return a NULL instead.
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*/
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Node *
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build_column_default(Relation rel, int attrno)
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{
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TupleDesc rd_att = rel->rd_att;
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Form_pg_attribute att_tup = rd_att->attrs[attrno - 1];
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Oid atttype = att_tup->atttypid;
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int32 atttypmod = att_tup->atttypmod;
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Node *expr = NULL;
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Oid exprtype;
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/*
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* Scan to see if relation has a default for this column.
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*/
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if (rd_att->constr && rd_att->constr->num_defval > 0)
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{
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AttrDefault *defval = rd_att->constr->defval;
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int ndef = rd_att->constr->num_defval;
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while (--ndef >= 0)
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{
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if (attrno == defval[ndef].adnum)
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{
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/*
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* Found it, convert string representation to node tree.
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*/
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expr = stringToNode(defval[ndef].adbin);
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break;
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}
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}
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}
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|
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if (expr == NULL)
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{
|
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/*
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* No per-column default, so look for a default for the type
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* itself.
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*/
|
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if (att_tup->attisset)
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{
|
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/*
|
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* Set attributes are represented as OIDs no matter what the
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* set element type is, and the element type's default is
|
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* irrelevant too.
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*/
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}
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else
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expr = get_typdefault(atttype);
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}
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|
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if (expr == NULL)
|
|
return NULL; /* No default anywhere */
|
|
|
|
/*
|
|
* Make sure the value is coerced to the target column type (might not
|
|
* be right type yet if it's not a constant!) This should match the
|
|
* parser's processing of non-defaulted expressions --- see
|
|
* updateTargetListEntry().
|
|
*/
|
|
exprtype = exprType(expr);
|
|
|
|
expr = coerce_to_target_type(NULL, /* no UNKNOWN params here */
|
|
expr, exprtype,
|
|
atttype, atttypmod,
|
|
COERCION_ASSIGNMENT,
|
|
COERCE_IMPLICIT_CAST);
|
|
/*
|
|
* This really shouldn't fail; should have checked the default's
|
|
* type when it was created ...
|
|
*/
|
|
if (expr == NULL)
|
|
elog(ERROR, "Column \"%s\" is of type %s"
|
|
" but default expression is of type %s"
|
|
"\n\tYou will need to rewrite or cast the expression",
|
|
NameStr(att_tup->attname),
|
|
format_type_be(atttype),
|
|
format_type_be(exprtype));
|
|
|
|
return expr;
|
|
}
|
|
|
|
|
|
/*
|
|
* matchLocks -
|
|
* match the list of locks and returns the matching rules
|
|
*/
|
|
static List *
|
|
matchLocks(CmdType event,
|
|
RuleLock *rulelocks,
|
|
int varno,
|
|
Query *parsetree)
|
|
{
|
|
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 == event)
|
|
{
|
|
if (parsetree->commandType != CMD_SELECT ||
|
|
(oneLock->attrno == -1 ?
|
|
rangeTableEntry_used((Node *) parsetree, varno, 0) :
|
|
attribute_used((Node *) parsetree,
|
|
varno, oneLock->attrno, 0)))
|
|
matching_locks = lappend(matching_locks, oneLock);
|
|
}
|
|
}
|
|
|
|
return matching_locks;
|
|
}
|
|
|
|
|
|
static Query *
|
|
ApplyRetrieveRule(Query *parsetree,
|
|
RewriteRule *rule,
|
|
int rt_index,
|
|
bool relation_level,
|
|
Relation relation,
|
|
bool relIsUsed,
|
|
List *activeRIRs)
|
|
{
|
|
Query *rule_action;
|
|
RangeTblEntry *rte,
|
|
*subrte;
|
|
|
|
if (length(rule->actions) != 1)
|
|
elog(ERROR, "ApplyRetrieveRule: expected just one rule action");
|
|
if (rule->qual != NULL)
|
|
elog(ERROR, "ApplyRetrieveRule: can't handle qualified ON SELECT rule");
|
|
if (!relation_level)
|
|
elog(ERROR, "ApplyRetrieveRule: can't handle per-attribute ON SELECT rule");
|
|
|
|
/*
|
|
* Make a modifiable copy of the view query, and recursively expand
|
|
* any view references inside it.
|
|
*/
|
|
rule_action = copyObject(lfirst(rule->actions));
|
|
|
|
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.
|
|
*/
|
|
rte = rt_fetch(rt_index, parsetree->rtable);
|
|
|
|
rte->rtekind = RTE_SUBQUERY;
|
|
rte->relid = InvalidOid;
|
|
rte->subquery = rule_action;
|
|
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.
|
|
*/
|
|
subrte = rt_fetch(PRS2_OLD_VARNO, rule_action->rtable);
|
|
Assert(subrte->relid == relation->rd_id);
|
|
subrte->checkForRead = rte->checkForRead;
|
|
subrte->checkForWrite = rte->checkForWrite;
|
|
subrte->checkAsUser = rte->checkAsUser;
|
|
|
|
rte->checkForRead = false; /* no permission check on subquery itself */
|
|
rte->checkForWrite = false;
|
|
rte->checkAsUser = InvalidOid;
|
|
|
|
/*
|
|
* FOR UPDATE of view?
|
|
*/
|
|
if (intMember(rt_index, parsetree->rowMarks))
|
|
{
|
|
/*
|
|
* Remove the view from the list of rels that will actually be
|
|
* marked FOR UPDATE by the executor. It will still be access-
|
|
* checked for write access, though.
|
|
*/
|
|
parsetree->rowMarks = lremovei(rt_index, parsetree->rowMarks);
|
|
|
|
/*
|
|
* Set up the view's referenced tables as if FOR UPDATE.
|
|
*/
|
|
markQueryForUpdate(rule_action, true);
|
|
}
|
|
|
|
return parsetree;
|
|
}
|
|
|
|
/*
|
|
* Recursively mark all relations used by a view as FOR UPDATE.
|
|
*
|
|
* 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 transformForUpdate() routine.
|
|
*/
|
|
static void
|
|
markQueryForUpdate(Query *qry, bool skipOldNew)
|
|
{
|
|
Index rti = 0;
|
|
List *l;
|
|
|
|
foreach(l, qry->rtable)
|
|
{
|
|
RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
|
|
|
|
rti++;
|
|
|
|
/* Ignore OLD and NEW entries if we are at top level of view */
|
|
if (skipOldNew &&
|
|
(rti == PRS2_OLD_VARNO || rti == PRS2_NEW_VARNO))
|
|
continue;
|
|
|
|
if (rte->rtekind == RTE_RELATION)
|
|
{
|
|
if (!intMember(rti, qry->rowMarks))
|
|
qry->rowMarks = lappendi(qry->rowMarks, rti);
|
|
rte->checkForWrite = true;
|
|
}
|
|
else if (rte->rtekind == RTE_SUBQUERY)
|
|
{
|
|
/* FOR UPDATE of subquery is propagated to subquery's rels */
|
|
markQueryForUpdate(rte->subquery, false);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* 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, List *activeRIRs)
|
|
{
|
|
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,
|
|
activeRIRs);
|
|
/* 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,
|
|
(void *) activeRIRs);
|
|
}
|
|
|
|
|
|
/*
|
|
* fireRIRrules -
|
|
* Apply all RIR rules on each rangetable entry in a query
|
|
*/
|
|
static Query *
|
|
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...
|
|
*/
|
|
rt_index = 0;
|
|
while (rt_index < length(parsetree->rtable))
|
|
{
|
|
RangeTblEntry *rte;
|
|
Relation rel;
|
|
List *locks;
|
|
RuleLock *rules;
|
|
RewriteRule *rule;
|
|
LOCKMODE lockmode;
|
|
bool relIsUsed;
|
|
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);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Joins and other non-relation RTEs can be ignored completely.
|
|
*/
|
|
if (rte->rtekind != RTE_RELATION)
|
|
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.
|
|
*/
|
|
relIsUsed = rangeTableEntry_used((Node *) parsetree, rt_index, 0);
|
|
|
|
if (!relIsUsed && rt_index != parsetree->resultRelation)
|
|
continue;
|
|
|
|
/*
|
|
* This may well be the first access to the relation during the
|
|
* current statement (it will be, if this Query was extracted from
|
|
* a rule or somehow got here other than via the parser).
|
|
* Therefore, 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
|
|
* RewriteQuery() already got the right lock on it, so we need no
|
|
* additional lock. Otherwise, check to see if the relation is
|
|
* accessed FOR UPDATE or not.
|
|
*/
|
|
if (rt_index == parsetree->resultRelation)
|
|
lockmode = NoLock;
|
|
else if (intMember(rt_index, parsetree->rowMarks))
|
|
lockmode = RowShareLock;
|
|
else
|
|
lockmode = AccessShareLock;
|
|
|
|
rel = heap_open(rte->relid, lockmode);
|
|
|
|
/*
|
|
* Collect the RIR rules that we must apply
|
|
*/
|
|
rules = rel->rd_rules;
|
|
if (rules == NULL)
|
|
{
|
|
heap_close(rel, NoLock);
|
|
continue;
|
|
}
|
|
locks = NIL;
|
|
for (i = 0; i < rules->numLocks; i++)
|
|
{
|
|
rule = rules->rules[i];
|
|
if (rule->event != CMD_SELECT)
|
|
continue;
|
|
|
|
if (rule->attrno > 0)
|
|
{
|
|
/* per-attr rule; do we need it? */
|
|
if (!attribute_used((Node *) parsetree, rt_index,
|
|
rule->attrno, 0))
|
|
continue;
|
|
}
|
|
|
|
locks = lappend(locks, rule);
|
|
}
|
|
|
|
/*
|
|
* If we found any, apply them --- but first check for recursion!
|
|
*/
|
|
if (locks != NIL)
|
|
{
|
|
List *newActiveRIRs;
|
|
List *l;
|
|
|
|
if (oidMember(RelationGetRelid(rel), activeRIRs))
|
|
elog(ERROR, "Infinite recursion detected in rules for relation %s",
|
|
RelationGetRelationName(rel));
|
|
newActiveRIRs = lconso(RelationGetRelid(rel), activeRIRs);
|
|
|
|
foreach(l, locks)
|
|
{
|
|
rule = lfirst(l);
|
|
|
|
parsetree = ApplyRetrieveRule(parsetree,
|
|
rule,
|
|
rt_index,
|
|
rule->attrno == -1,
|
|
rel,
|
|
relIsUsed,
|
|
newActiveRIRs);
|
|
}
|
|
}
|
|
|
|
heap_close(rel, NoLock);
|
|
}
|
|
|
|
/*
|
|
* Recurse into sublink subqueries, too. But we already did the ones
|
|
* in the rtable.
|
|
*/
|
|
if (parsetree->hasSubLinks)
|
|
query_tree_walker(parsetree, fireRIRonSubLink, (void *) activeRIRs,
|
|
QTW_IGNORE_RT_SUBQUERIES);
|
|
|
|
/*
|
|
* If the query was marked having aggregates, check if this is still
|
|
* true after rewriting. Ditto for sublinks. Note there should be no
|
|
* aggs in the qual at this point. (Does this code still do anything
|
|
* useful? The view-becomes-subselect-in-FROM approach doesn't look
|
|
* like it could remove aggs or sublinks...)
|
|
*/
|
|
if (parsetree->hasAggs)
|
|
{
|
|
parsetree->hasAggs = checkExprHasAggs((Node *) parsetree);
|
|
if (parsetree->hasAggs)
|
|
if (checkExprHasAggs((Node *) parsetree->jointree))
|
|
elog(ERROR, "fireRIRrules: failed to remove aggs from qual");
|
|
}
|
|
if (parsetree->hasSubLinks)
|
|
parsetree->hasSubLinks = checkExprHasSubLink((Node *) parsetree);
|
|
|
|
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)
|
|
{
|
|
Query *new_tree = (Query *) copyObject(parsetree);
|
|
Node *new_qual = (Node *) copyObject(rule_qual);
|
|
|
|
/* 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 = ResolveNew(new_qual,
|
|
PRS2_NEW_VARNO,
|
|
0,
|
|
parsetree->targetList,
|
|
event,
|
|
rt_index);
|
|
/* And attach the fixed qual */
|
|
AddInvertedQual(new_tree, new_qual);
|
|
|
|
return new_tree;
|
|
}
|
|
|
|
|
|
/*
|
|
* 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)
|
|
* *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,
|
|
Query **qual_product)
|
|
{
|
|
List *results = NIL;
|
|
List *i;
|
|
|
|
foreach(i, locks)
|
|
{
|
|
RewriteRule *rule_lock = (RewriteRule *) lfirst(i);
|
|
Node *event_qual = rule_lock->qual;
|
|
List *actions = rule_lock->actions;
|
|
QuerySource qsrc;
|
|
List *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 = 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);
|
|
|
|
rule_action->querySource = qsrc;
|
|
rule_action->canSetTag = false; /* might change later */
|
|
|
|
results = lappend(results, rule_action);
|
|
}
|
|
}
|
|
|
|
return results;
|
|
}
|
|
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static List *
|
|
RewriteQuery(Query *parsetree, List *rewrite_events)
|
|
{
|
|
CmdType event = parsetree->commandType;
|
|
bool instead = false;
|
|
Query *qual_product = NULL;
|
|
List *rewritten = NIL;
|
|
|
|
/*
|
|
* 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?)
|
|
*/
|
|
if (event != CMD_SELECT && event != CMD_UTILITY)
|
|
{
|
|
int result_relation;
|
|
RangeTblEntry *rt_entry;
|
|
Relation rt_entry_relation;
|
|
List *locks;
|
|
|
|
result_relation = parsetree->resultRelation;
|
|
Assert(result_relation != 0);
|
|
rt_entry = rt_fetch(result_relation, parsetree->rtable);
|
|
Assert(rt_entry->rtekind == RTE_RELATION);
|
|
|
|
/*
|
|
* This may well be the first access to the result relation during the
|
|
* current statement (it will be, if this Query was extracted from a
|
|
* rule or somehow got here other than via the parser). Therefore,
|
|
* grab the appropriate lock type for a result relation, and do not
|
|
* release it until end of transaction. This protects the rewriter
|
|
* and planner against schema changes mid-query.
|
|
*/
|
|
rt_entry_relation = heap_open(rt_entry->relid, RowExclusiveLock);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/*
|
|
* Collect and apply the appropriate rules.
|
|
*/
|
|
locks = matchLocks(event, rt_entry_relation->rd_rules,
|
|
result_relation, parsetree);
|
|
|
|
if (locks != NIL)
|
|
{
|
|
List *product_queries;
|
|
|
|
product_queries = fireRules(parsetree,
|
|
result_relation,
|
|
event,
|
|
locks,
|
|
&instead,
|
|
&qual_product);
|
|
|
|
/*
|
|
* If we got any product queries, recursively rewrite them
|
|
* --- but first check for recursion!
|
|
*/
|
|
if (product_queries != NIL)
|
|
{
|
|
List *n;
|
|
rewrite_event *rev;
|
|
|
|
foreach(n, rewrite_events)
|
|
{
|
|
rev = (rewrite_event *) lfirst(n);
|
|
if (rev->relation == RelationGetRelid(rt_entry_relation) &&
|
|
rev->event == event)
|
|
elog(ERROR, "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 = lcons(rev, rewrite_events);
|
|
|
|
foreach(n, product_queries)
|
|
{
|
|
Query *pt = (Query *) lfirst(n);
|
|
List *newstuff;
|
|
|
|
newstuff = RewriteQuery(pt, rewrite_events);
|
|
rewritten = nconc(rewritten, newstuff);
|
|
}
|
|
}
|
|
}
|
|
|
|
heap_close(rt_entry_relation, NoLock); /* keep lock! */
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
}
|
|
|
|
return rewritten;
|
|
}
|
|
|
|
|
|
/*
|
|
* QueryRewrite -
|
|
* Primary entry point to the query rewriter.
|
|
* Rewrite one query via query rewrite system, possibly returning 0
|
|
* or many queries.
|
|
*
|
|
* NOTE: The code in QueryRewrite was formerly in pg_parse_and_plan(), and was
|
|
* moved here so that it would be invoked during EXPLAIN.
|
|
*/
|
|
List *
|
|
QueryRewrite(Query *parsetree)
|
|
{
|
|
List *querylist;
|
|
List *results = NIL;
|
|
List *l;
|
|
CmdType origCmdType;
|
|
bool foundOriginalQuery;
|
|
Query *lastInstead;
|
|
|
|
/*
|
|
* Step 1
|
|
*
|
|
* Apply all non-SELECT rules possibly getting 0 or many queries
|
|
*/
|
|
querylist = RewriteQuery(parsetree, NIL);
|
|
|
|
/*
|
|
* Step 2
|
|
*
|
|
* Apply all the RIR rules on each query
|
|
*/
|
|
foreach(l, querylist)
|
|
{
|
|
Query *query = (Query *) lfirst(l);
|
|
|
|
query = fireRIRrules(query, NIL);
|
|
|
|
/*
|
|
* If the query target was rewritten as a view, complain.
|
|
*/
|
|
if (query->resultRelation)
|
|
{
|
|
RangeTblEntry *rte = rt_fetch(query->resultRelation,
|
|
query->rtable);
|
|
|
|
if (rte->rtekind == RTE_SUBQUERY)
|
|
{
|
|
switch (query->commandType)
|
|
{
|
|
case CMD_INSERT:
|
|
elog(ERROR, "Cannot insert into a view"
|
|
"\n\tYou need an unconditional ON INSERT DO INSTEAD rule");
|
|
break;
|
|
case CMD_UPDATE:
|
|
elog(ERROR, "Cannot update a view"
|
|
"\n\tYou need an unconditional ON UPDATE DO INSTEAD rule");
|
|
break;
|
|
case CMD_DELETE:
|
|
elog(ERROR, "Cannot delete from a view"
|
|
"\n\tYou need an unconditional ON DELETE DO INSTEAD rule");
|
|
break;
|
|
default:
|
|
elog(ERROR, "QueryRewrite: unexpected commandType %d",
|
|
(int) query->commandType);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
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;
|
|
}
|