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performance problem pointed out by phil@vodafone: to wit, we were spending O(N^2) time to check dropped-ness in an N-deep join tree, even in the case where the tree was freshly constructed and couldn't possibly mention any dropped columns. Instead of recursing in get_rte_attribute_is_dropped(), change the data structure definition: the joinaliasvars list of a JOIN RTE must have a NULL Const instead of a Var at any position that references a now-dropped column. This costs nothing during normal parse-rewrite-plan path, and instead we have a linear-time update to make when loading a stored rule that might contain now-dropped columns. While at it, move the responsibility for acquring locks on relations referenced by rules into this separate function (which I therefore chose to call AcquireRewriteLocks). This saves effort --- namely, duplicated lock grabs in parser and rewriter --- in the normal path at a cost of one extra non-locked heap_open() in the stored-rule path; seems a good tradeoff. A fringe benefit is that it is now *much* clearer that we acquire lock on relations referenced in rules before we make any rewriter decisions based on their properties. (I don't know of any bug of that ilk, but it wasn't exactly clear before.)
1595 lines
45 KiB
C
1595 lines
45 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) 1996-2005, 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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* $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.153 2005/06/03 23:05:28 tgl 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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{
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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 bool acquireLocksOnSubLinks(Node *node, void *context);
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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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const char *attrName);
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static Node *get_assignment_input(Node *node);
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static void markQueryForLocking(Query *qry, bool forUpdate, 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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* AcquireRewriteLocks -
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* Acquire suitable locks on all the relations mentioned in the Query.
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* These locks will ensure that the relation schemas don't change under us
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* while we are rewriting and planning the query.
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*
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* A secondary purpose of this routine is to fix up JOIN RTE references to
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* dropped columns (see details below). Because the RTEs are modified in
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* place, it is generally appropriate for the caller of this routine to have
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* first done a copyObject() to make a writable copy of the querytree in the
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* current memory context.
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*
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* This processing can, and for efficiency's sake should, be skipped when the
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* querytree has just been built by the parser: parse analysis already got
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* all the same locks we'd get here, and the parser will have omitted dropped
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* columns from JOINs to begin with. But we must do this whenever we are
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* dealing with a querytree produced earlier than the current command.
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*
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* About JOINs and dropped columns: although the parser never includes an
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* already-dropped column in a JOIN RTE's alias var list, it is possible for
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* such a list in a stored rule to include references to dropped columns.
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* (If the column is not explicitly referenced anywhere else in the query,
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* the dependency mechanism won't consider it used by the rule and so won't
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* prevent the column drop.) To support get_rte_attribute_is_dropped(),
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* we replace join alias vars that reference dropped columns with NULL Const
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* nodes.
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*
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* (In PostgreSQL 8.0, we did not do this processing but instead had
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* get_rte_attribute_is_dropped() recurse to detect dropped columns in joins.
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* That approach had horrible performance unfortunately; in particular
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* construction of a nested join was O(N^2) in the nesting depth.)
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*/
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void
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AcquireRewriteLocks(Query *parsetree)
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{
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ListCell *l;
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int rt_index;
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/*
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* First, process RTEs of the current query level.
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*/
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rt_index = 0;
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foreach(l, parsetree->rtable)
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{
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RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
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Relation rel;
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LOCKMODE lockmode;
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List *newaliasvars;
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ListCell *ll;
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++rt_index;
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switch (rte->rtekind)
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{
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case RTE_RELATION:
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/*
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* Grab the appropriate lock type for the relation, and
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* do not release it until end of transaction. This protects
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* the rewriter and planner against schema changes mid-query.
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*
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* If the relation is the query's result relation, then we
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* need RowExclusiveLock. Otherwise, check to see if the
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* relation is accessed FOR UPDATE/SHARE or not. We can't
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* just grab AccessShareLock because then the executor
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* would be trying to upgrade the lock, leading to possible
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* deadlocks.
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*/
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if (rt_index == parsetree->resultRelation)
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lockmode = RowExclusiveLock;
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else if (list_member_int(parsetree->rowMarks, rt_index))
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lockmode = RowShareLock;
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else
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lockmode = AccessShareLock;
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rel = heap_open(rte->relid, lockmode);
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heap_close(rel, NoLock);
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break;
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case RTE_JOIN:
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/*
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* Scan the join's alias var list to see if any columns
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* have been dropped, and if so replace those Vars with
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* NULL Consts.
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*/
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newaliasvars = NIL;
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foreach(ll, rte->joinaliasvars)
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{
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Var *aliasvar = (Var *) lfirst(ll);
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/*
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* If the list item isn't a simple Var, then it must
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* represent a merged column, ie a USING column, and so it
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* couldn't possibly be dropped, since it's referenced in
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* the join clause. (Conceivably it could also be a
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* NULL constant already? But that's OK too.)
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*/
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if (IsA(aliasvar, Var))
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{
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/*
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* The elements of an alias list have to refer to
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* earlier RTEs of the same rtable, because that's
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* the order the planner builds things in. So we
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* already processed the referenced RTE, and so it's
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* safe to use get_rte_attribute_is_dropped on it.
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* (This might not hold after rewriting or planning,
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* but it's OK to assume here.)
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*/
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Assert(aliasvar->varlevelsup == 0);
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if (aliasvar->varno >= rt_index)
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elog(ERROR, "unexpected varno %d in JOIN RTE %d",
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aliasvar->varno, rt_index);
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if (get_rte_attribute_is_dropped(
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rt_fetch(aliasvar->varno, parsetree->rtable),
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aliasvar->varattno))
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{
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/*
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* can't use vartype here, since that might be a
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* now-dropped type OID, but it doesn't really
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* matter what type the Const claims to be.
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*/
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aliasvar = (Var *) makeNullConst(INT4OID);
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}
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}
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newaliasvars = lappend(newaliasvars, aliasvar);
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}
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rte->joinaliasvars = newaliasvars;
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break;
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case RTE_SUBQUERY:
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/*
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* The subquery RTE itself is all right, but we have to
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* recurse to process the represented subquery.
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*/
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AcquireRewriteLocks(rte->subquery);
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break;
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default:
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/* ignore other types of RTEs */
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break;
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}
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}
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/*
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* Recurse into sublink subqueries, too. But we already did the ones
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* in the rtable.
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*/
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if (parsetree->hasSubLinks)
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query_tree_walker(parsetree, acquireLocksOnSubLinks, NULL,
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QTW_IGNORE_RT_SUBQUERIES);
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}
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/*
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* Walker to find sublink subqueries for AcquireRewriteLocks
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*/
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static bool
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acquireLocksOnSubLinks(Node *node, void *context)
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{
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if (node == NULL)
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return false;
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if (IsA(node, SubLink))
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{
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SubLink *sub = (SubLink *) node;
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/* Do what we came for */
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AcquireRewriteLocks((Query *) sub->subselect);
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/* Fall through to process lefthand args of SubLink */
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}
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/*
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* Do NOT recurse into Query nodes, because AcquireRewriteLocks already
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* processed subselects of subselects for us.
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*/
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return expression_tree_walker(node, acquireLocksOnSubLinks, context);
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}
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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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int rt_length;
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Query *sub_action;
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Query **sub_action_ptr;
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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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/*
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* Acquire necessary locks and fix any deleted JOIN RTE entries.
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*/
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AcquireRewriteLocks(rule_action);
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(void) acquireLocksOnSubLinks(rule_qual, NULL);
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current_varno = rt_index;
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rt_length = list_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 we leave them all in place for two reasons:
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*
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* We'd have a much harder job to adjust the query's varnos if we
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* selectively removed RT entries.
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*
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* If the rule is INSTEAD, then the original query won't be executed at
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* all, and so its rtable must be preserved so that the executor will
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* do the correct permissions checks on it.
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*
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* RT entries that are not referenced in the completed jointree will be
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* ignored by the planner, so they do not affect query semantics. But
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* any permissions checks specified in them will be applied during
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* executor startup (see ExecCheckRTEPerms()). This allows us to
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* check that the caller has, say, insert-permission on a view, when
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* the view is not semantically referenced at all in the resulting
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* query.
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*
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* When a rule is not INSTEAD, the permissions checks done on its copied
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* RT entries will be redundant with those done during execution of
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* the original query, but we don't bother to treat that case
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* differently.
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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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sub_action->rtable = list_concat((List *) copyObject(parsetree->rtable),
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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->commandType != CMD_UTILITY)
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{
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bool keeporig;
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List *newjointree;
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Assert(sub_action->jointree != NULL);
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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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if (newjointree != NIL)
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{
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/*
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* If sub_action is a setop, manipulating its jointree will do
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* no good at all, because the jointree is dummy. (Perhaps
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* someday we could push the joining and quals down to the
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* member statements of the setop?)
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*/
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if (sub_action->setOperations != NULL)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
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sub_action->jointree->fromlist =
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list_concat(newjointree, sub_action->jointree->fromlist);
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}
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}
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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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sub_action->commandType != CMD_UTILITY)
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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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sub_action->rtable,
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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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ListCell *l;
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if (removert)
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{
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foreach(l, newjointree)
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{
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RangeTblRef *rtr = lfirst(l);
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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 = list_delete_ptr(newjointree, rtr);
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/*
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* foreach is safe because we exit loop after
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* list_delete...
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*/
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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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/*
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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.) Also, for both INSERT
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* and UPDATE, replace explicit DEFAULT specifications with column default
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* expressions.
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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. Multiple entries are only allowed for INSERT/UPDATE of
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* portions of an array or record field, for example
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* 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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TargetEntry **new_tles;
|
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List *new_tlist = NIL;
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List *junk_tlist = NIL;
|
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Form_pg_attribute att_tup;
|
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int attrno,
|
|
next_junk_attrno,
|
|
numattrs;
|
|
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.
|
|
*
|
|
* 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, parsetree->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 = target_relation->rd_att->attrs[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];
|
|
|
|
att_tup = target_relation->rd_att->attrs[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.
|
|
*/
|
|
if ((new_tle == NULL && commandType == CMD_INSERT) ||
|
|
(new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)))
|
|
{
|
|
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 = (Node *) makeConst(att_tup->atttypid,
|
|
att_tup->attlen,
|
|
(Datum) 0,
|
|
true, /* isnull */
|
|
att_tup->attbyval);
|
|
/* this is to catch a NOT NULL domain constraint */
|
|
new_expr = coerce_to_domain(new_expr,
|
|
InvalidOid,
|
|
att_tup->atttypid,
|
|
COERCE_IMPLICIT_CAST,
|
|
false,
|
|
false);
|
|
}
|
|
}
|
|
|
|
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);
|
|
|
|
parsetree->targetList = 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;
|
|
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 ArrayRef 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, x))
|
|
* However, we can ignore the substructure and just consider the top
|
|
* FieldStore or ArrayRef from each assignment, because it works to
|
|
* combine these as
|
|
* FieldStore(FieldStore(col, fld1,
|
|
* FieldStore(placeholder, subfld1, x)),
|
|
* fld2, FieldStore(placeholder, subfld2, x))
|
|
* 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
|
|
* ArrayRefs are involved though.
|
|
*----------
|
|
*/
|
|
src_expr = (Node *) src_tle->expr;
|
|
prior_expr = (Node *) prior_tle->expr;
|
|
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(list_copy(((FieldStore *) prior_expr)->newvals),
|
|
list_copy(((FieldStore *) src_expr)->newvals));
|
|
fstore->fieldnums =
|
|
list_concat(list_copy(((FieldStore *) prior_expr)->fieldnums),
|
|
list_copy(((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, ArrayRef))
|
|
{
|
|
ArrayRef *aref = makeNode(ArrayRef);
|
|
|
|
memcpy(aref, src_expr, sizeof(ArrayRef));
|
|
aref->refexpr = (Expr *) prior_expr;
|
|
newexpr = (Node *) aref;
|
|
}
|
|
else
|
|
{
|
|
elog(ERROR, "can't happen");
|
|
newexpr = NULL;
|
|
}
|
|
|
|
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, ArrayRef))
|
|
{
|
|
ArrayRef *aref = (ArrayRef *) node;
|
|
|
|
if (aref->refassgnexpr == NULL)
|
|
return NULL;
|
|
return (Node *) aref->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 = rd_att->attrs[attrno - 1];
|
|
Oid atttype = att_tup->atttypid;
|
|
int32 atttypmod = att_tup->atttypmod;
|
|
Node *expr = NULL;
|
|
Oid exprtype;
|
|
|
|
/*
|
|
* Scan to see if relation has a default for this column.
|
|
*/
|
|
if (rd_att->constr && rd_att->constr->num_defval > 0)
|
|
{
|
|
AttrDefault *defval = rd_att->constr->defval;
|
|
int ndef = rd_att->constr->num_defval;
|
|
|
|
while (--ndef >= 0)
|
|
{
|
|
if (attrno == defval[ndef].adnum)
|
|
{
|
|
/*
|
|
* Found it, convert string representation to node tree.
|
|
*/
|
|
expr = stringToNode(defval[ndef].adbin);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (expr == NULL)
|
|
{
|
|
/*
|
|
* No per-column default, so look for a default for the type
|
|
* itself.
|
|
*/
|
|
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
|
|
* updateTargetListEntry().
|
|
*/
|
|
exprtype = exprType(expr);
|
|
|
|
expr = coerce_to_target_type(NULL, /* no UNKNOWN params here */
|
|
expr, exprtype,
|
|
atttype, atttypmod,
|
|
COERCION_ASSIGNMENT,
|
|
COERCE_IMPLICIT_CAST);
|
|
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;
|
|
}
|
|
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
|
|
/*
|
|
* ApplyRetrieveRule - expand an ON SELECT rule
|
|
*/
|
|
static Query *
|
|
ApplyRetrieveRule(Query *parsetree,
|
|
RewriteRule *rule,
|
|
int rt_index,
|
|
bool relation_level,
|
|
Relation relation,
|
|
List *activeRIRs)
|
|
{
|
|
Query *rule_action;
|
|
RangeTblEntry *rte,
|
|
*subrte;
|
|
|
|
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");
|
|
if (!relation_level)
|
|
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.
|
|
*/
|
|
rule_action = copyObject(linitial(rule->actions));
|
|
|
|
AcquireRewriteLocks(rule_action);
|
|
|
|
/*
|
|
* Recursively expand any view references inside the view.
|
|
*/
|
|
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->requiredPerms = rte->requiredPerms;
|
|
subrte->checkAsUser = rte->checkAsUser;
|
|
|
|
rte->requiredPerms = 0; /* no permission check on subquery itself */
|
|
rte->checkAsUser = 0;
|
|
|
|
/*
|
|
* FOR UPDATE/SHARE of view?
|
|
*/
|
|
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.
|
|
*/
|
|
parsetree->rowMarks = list_delete_int(parsetree->rowMarks, rt_index);
|
|
|
|
/*
|
|
* Set up the view's referenced tables as if FOR UPDATE/SHARE.
|
|
*/
|
|
markQueryForLocking(rule_action, parsetree->forUpdate, true);
|
|
}
|
|
|
|
return parsetree;
|
|
}
|
|
|
|
/*
|
|
* Recursively mark all relations used by a view as FOR 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 transformLocking() routine.
|
|
*/
|
|
static void
|
|
markQueryForLocking(Query *qry, bool forUpdate, bool skipOldNew)
|
|
{
|
|
Index rti = 0;
|
|
ListCell *l;
|
|
|
|
if (qry->rowMarks && forUpdate != qry->forUpdate)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("cannot use both FOR UPDATE and FOR SHARE in one query")));
|
|
qry->forUpdate = forUpdate;
|
|
|
|
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 (!list_member_int(qry->rowMarks, rti))
|
|
qry->rowMarks = lappend_int(qry->rowMarks, rti);
|
|
rte->requiredPerms |= ACL_SELECT_FOR_UPDATE;
|
|
}
|
|
else if (rte->rtekind == RTE_SUBQUERY)
|
|
{
|
|
/* FOR UPDATE/SHARE of subquery is propagated to subquery's rels */
|
|
markQueryForLocking(rte->subquery, forUpdate, 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 < 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);
|
|
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.
|
|
*/
|
|
if (rt_index != parsetree->resultRelation &&
|
|
!rangeTableEntry_used((Node *) parsetree, rt_index, 0))
|
|
continue;
|
|
|
|
/*
|
|
* We can use NoLock here since either the parser or
|
|
* AcquireRewriteLocks should have locked the rel already.
|
|
*/
|
|
rel = heap_open(rte->relid, NoLock);
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
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 = lcons_oid(RelationGetRelid(rel), activeRIRs);
|
|
|
|
foreach(l, locks)
|
|
{
|
|
rule = lfirst(l);
|
|
|
|
parsetree = ApplyRetrieveRule(parsetree,
|
|
rule,
|
|
rt_index,
|
|
rule->attrno == -1,
|
|
rel,
|
|
activeRIRs);
|
|
}
|
|
|
|
activeRIRs = list_delete_first(activeRIRs);
|
|
}
|
|
|
|
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);
|
|
|
|
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 = (Node *) copyObject(rule_qual);
|
|
|
|
/*
|
|
* 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, NULL);
|
|
|
|
/* 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->rtable,
|
|
parsetree->targetList,
|
|
event,
|
|
rt_index);
|
|
/* 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)
|
|
* *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;
|
|
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);
|
|
|
|
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);
|
|
|
|
/*
|
|
* We can use NoLock here since either the parser or
|
|
* AcquireRewriteLocks should have locked the rel already.
|
|
*/
|
|
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 (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)
|
|
{
|
|
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 = lcons(rev, rewrite_events);
|
|
|
|
foreach(n, product_queries)
|
|
{
|
|
Query *pt = (Query *) lfirst(n);
|
|
List *newstuff;
|
|
|
|
newstuff = RewriteQuery(pt, rewrite_events);
|
|
rewritten = list_concat(rewritten, newstuff);
|
|
}
|
|
|
|
rewrite_events = list_delete_first(rewrite_events);
|
|
}
|
|
}
|
|
|
|
heap_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);
|
|
}
|
|
}
|
|
|
|
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 parsetree must either have come straight from the parser,
|
|
* or have been scanned by AcquireRewriteLocks to acquire suitable locks.
|
|
*/
|
|
List *
|
|
QueryRewrite(Query *parsetree)
|
|
{
|
|
List *querylist;
|
|
List *results = NIL;
|
|
ListCell *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:
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("cannot insert into a view"),
|
|
errhint("You need an unconditional ON INSERT DO INSTEAD rule.")));
|
|
break;
|
|
case CMD_UPDATE:
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("cannot update a view"),
|
|
errhint("You need an unconditional ON UPDATE DO INSTEAD rule.")));
|
|
break;
|
|
case CMD_DELETE:
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("cannot delete from a view"),
|
|
errhint("You need an unconditional ON DELETE DO INSTEAD rule.")));
|
|
break;
|
|
default:
|
|
elog(ERROR, "unrecognized 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;
|
|
}
|