/*-------------------------------------------------------------------------
*
* rewriteHandler.c
+ * Primary module of query rewriter.
*
- * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- *
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.90 2001/03/22 03:59:44 momjian Exp $
+ * src/backend/rewrite/rewriteHandler.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
-#include "catalog/pg_operator.h"
+#include "access/sysattr.h"
#include "catalog/pg_type.h"
-#include "miscadmin.h"
#include "nodes/makefuncs.h"
-#include "optimizer/clauses.h"
-#include "optimizer/prep.h"
-#include "optimizer/var.h"
+#include "nodes/nodeFuncs.h"
#include "parser/analyze.h"
-#include "parser/parse_expr.h"
-#include "parser/parse_oper.h"
-#include "parser/parse_target.h"
+#include "parser/parse_coerce.h"
#include "parser/parsetree.h"
-#include "parser/parse_type.h"
+#include "rewrite/rewriteDefine.h"
+#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteManip.h"
+#include "utils/builtins.h"
#include "utils/lsyscache.h"
+#include "commands/trigger.h"
+
+/* We use a list of these to detect recursion in RewriteQuery */
+typedef struct rewrite_event
+{
+ Oid relation; /* OID of relation having rules */
+ CmdType event; /* type of rule being fired */
+} rewrite_event;
-static RewriteInfo *gatherRewriteMeta(Query *parsetree,
+static bool acquireLocksOnSubLinks(Node *node, void *context);
+static Query *rewriteRuleAction(Query *parsetree,
Query *rule_action,
Node *rule_qual,
int rt_index,
CmdType event,
- bool instead_flag);
+ bool *returning_flag);
static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
-static void markQueryForUpdate(Query *qry, bool skipOldNew);
+static void rewriteTargetListIU(Query *parsetree, Relation target_relation,
+ List **attrno_list);
+static TargetEntry *process_matched_tle(TargetEntry *src_tle,
+ TargetEntry *prior_tle,
+ const char *attrName);
+static Node *get_assignment_input(Node *node);
+static void rewriteValuesRTE(RangeTblEntry *rte, Relation target_relation,
+ List *attrnos);
+static void rewriteTargetListUD(Query *parsetree, RangeTblEntry *target_rte,
+ Relation target_relation);
+static void markQueryForLocking(Query *qry, Node *jtnode,
+ bool forUpdate, bool noWait, bool pushedDown);
static List *matchLocks(CmdType event, RuleLock *rulelocks,
int varno, Query *parsetree);
-static Query *fireRIRrules(Query *parsetree);
+static Query *fireRIRrules(Query *parsetree, List *activeRIRs,
+ bool forUpdatePushedDown);
/*
- * gatherRewriteMeta -
- * Gather meta information about parsetree, and rule. Fix rule body
- * and qualifier so that they can be mixed with the parsetree and
- * maintain semantic validity
+ * AcquireRewriteLocks -
+ * Acquire suitable locks on all the relations mentioned in the Query.
+ * These locks will ensure that the relation schemas don't change under us
+ * while we are rewriting and planning the query.
+ *
+ * forUpdatePushedDown indicates that a pushed-down FOR UPDATE/SHARE applies
+ * to the current subquery, requiring all rels to be opened with RowShareLock.
+ * This should always be false at the start of the recursion.
+ *
+ * A secondary purpose of this routine is to fix up JOIN RTE references to
+ * dropped columns (see details below). Because the RTEs are modified in
+ * place, it is generally appropriate for the caller of this routine to have
+ * first done a copyObject() to make a writable copy of the querytree in the
+ * current memory context.
+ *
+ * This processing can, and for efficiency's sake should, be skipped when the
+ * querytree has just been built by the parser: parse analysis already got
+ * all the same locks we'd get here, and the parser will have omitted dropped
+ * columns from JOINs to begin with. But we must do this whenever we are
+ * dealing with a querytree produced earlier than the current command.
+ *
+ * About JOINs and dropped columns: although the parser never includes an
+ * already-dropped column in a JOIN RTE's alias var list, it is possible for
+ * such a list in a stored rule to include references to dropped columns.
+ * (If the column is not explicitly referenced anywhere else in the query,
+ * the dependency mechanism won't consider it used by the rule and so won't
+ * prevent the column drop.) To support get_rte_attribute_is_dropped(),
+ * we replace join alias vars that reference dropped columns with NULL Const
+ * nodes.
+ *
+ * (In PostgreSQL 8.0, we did not do this processing but instead had
+ * get_rte_attribute_is_dropped() recurse to detect dropped columns in joins.
+ * That approach had horrible performance unfortunately; in particular
+ * construction of a nested join was O(N^2) in the nesting depth.)
*/
-static RewriteInfo *
-gatherRewriteMeta(Query *parsetree,
+void
+AcquireRewriteLocks(Query *parsetree, bool forUpdatePushedDown)
+{
+ ListCell *l;
+ int rt_index;
+
+ /*
+ * First, process RTEs of the current query level.
+ */
+ rt_index = 0;
+ foreach(l, parsetree->rtable)
+ {
+ RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
+ Relation rel;
+ LOCKMODE lockmode;
+ List *newaliasvars;
+ Index curinputvarno;
+ RangeTblEntry *curinputrte;
+ ListCell *ll;
+
+ ++rt_index;
+ switch (rte->rtekind)
+ {
+ case RTE_RELATION:
+
+ /*
+ * Grab the appropriate lock type for the relation, and do not
+ * release it until end of transaction. This protects the
+ * rewriter and planner against schema changes mid-query.
+ *
+ * If the relation is the query's result relation, then we
+ * need RowExclusiveLock. Otherwise, check to see if the
+ * relation is accessed FOR UPDATE/SHARE or not. We can't
+ * just grab AccessShareLock because then the executor would
+ * be trying to upgrade the lock, leading to possible
+ * deadlocks.
+ */
+ if (rt_index == parsetree->resultRelation)
+ lockmode = RowExclusiveLock;
+ else if (forUpdatePushedDown ||
+ get_parse_rowmark(parsetree, rt_index) != NULL)
+ lockmode = RowShareLock;
+ else
+ lockmode = AccessShareLock;
+
+ rel = heap_open(rte->relid, lockmode);
+ heap_close(rel, NoLock);
+ break;
+
+ case RTE_JOIN:
+
+ /*
+ * Scan the join's alias var list to see if any columns have
+ * been dropped, and if so replace those Vars with NULL
+ * Consts.
+ *
+ * Since a join has only two inputs, we can expect to see
+ * multiple references to the same input RTE; optimize away
+ * multiple fetches.
+ */
+ newaliasvars = NIL;
+ curinputvarno = 0;
+ curinputrte = NULL;
+ foreach(ll, rte->joinaliasvars)
+ {
+ Var *aliasvar = (Var *) lfirst(ll);
+
+ /*
+ * If the list item isn't a simple Var, then it must
+ * represent a merged column, ie a USING column, and so it
+ * couldn't possibly be dropped, since it's referenced in
+ * the join clause. (Conceivably it could also be a NULL
+ * constant already? But that's OK too.)
+ */
+ if (IsA(aliasvar, Var))
+ {
+ /*
+ * The elements of an alias list have to refer to
+ * earlier RTEs of the same rtable, because that's the
+ * order the planner builds things in. So we already
+ * processed the referenced RTE, and so it's safe to
+ * use get_rte_attribute_is_dropped on it. (This might
+ * not hold after rewriting or planning, but it's OK
+ * to assume here.)
+ */
+ Assert(aliasvar->varlevelsup == 0);
+ if (aliasvar->varno != curinputvarno)
+ {
+ curinputvarno = aliasvar->varno;
+ if (curinputvarno >= rt_index)
+ elog(ERROR, "unexpected varno %d in JOIN RTE %d",
+ curinputvarno, rt_index);
+ curinputrte = rt_fetch(curinputvarno,
+ parsetree->rtable);
+ }
+ if (get_rte_attribute_is_dropped(curinputrte,
+ aliasvar->varattno))
+ {
+ /*
+ * can't use vartype here, since that might be a
+ * now-dropped type OID, but it doesn't really
+ * matter what type the Const claims to be.
+ */
+ aliasvar = (Var *) makeNullConst(INT4OID, -1);
+ }
+ }
+ newaliasvars = lappend(newaliasvars, aliasvar);
+ }
+ rte->joinaliasvars = newaliasvars;
+ break;
+
+ case RTE_SUBQUERY:
+
+ /*
+ * The subquery RTE itself is all right, but we have to
+ * recurse to process the represented subquery.
+ */
+ AcquireRewriteLocks(rte->subquery,
+ (forUpdatePushedDown ||
+ get_parse_rowmark(parsetree, rt_index) != NULL));
+ break;
+
+ default:
+ /* ignore other types of RTEs */
+ break;
+ }
+ }
+
+ /* Recurse into subqueries in WITH */
+ foreach(l, parsetree->cteList)
+ {
+ CommonTableExpr *cte = (CommonTableExpr *) lfirst(l);
+
+ AcquireRewriteLocks((Query *) cte->ctequery, false);
+ }
+
+ /*
+ * Recurse into sublink subqueries, too. But we already did the ones in
+ * the rtable and cteList.
+ */
+ if (parsetree->hasSubLinks)
+ query_tree_walker(parsetree, acquireLocksOnSubLinks, NULL,
+ QTW_IGNORE_RC_SUBQUERIES);
+}
+
+/*
+ * Walker to find sublink subqueries for AcquireRewriteLocks
+ */
+static bool
+acquireLocksOnSubLinks(Node *node, void *context)
+{
+ if (node == NULL)
+ return false;
+ if (IsA(node, SubLink))
+ {
+ SubLink *sub = (SubLink *) node;
+
+ /* Do what we came for */
+ AcquireRewriteLocks((Query *) sub->subselect, false);
+ /* Fall through to process lefthand args of SubLink */
+ }
+
+ /*
+ * Do NOT recurse into Query nodes, because AcquireRewriteLocks already
+ * processed subselects of subselects for us.
+ */
+ return expression_tree_walker(node, acquireLocksOnSubLinks, context);
+}
+
+
+/*
+ * rewriteRuleAction -
+ * Rewrite the rule action with appropriate qualifiers (taken from
+ * the triggering query).
+ *
+ * Input arguments:
+ * parsetree - original query
+ * rule_action - one action (query) of a rule
+ * rule_qual - WHERE condition of rule, or NULL if unconditional
+ * rt_index - RT index of result relation in original query
+ * event - type of rule event
+ * Output arguments:
+ * *returning_flag - set TRUE if we rewrite RETURNING clause in rule_action
+ * (must be initialized to FALSE)
+ * Return value:
+ * rewritten form of rule_action
+ */
+static Query *
+rewriteRuleAction(Query *parsetree,
Query *rule_action,
Node *rule_qual,
int rt_index,
CmdType event,
- bool instead_flag)
+ bool *returning_flag)
{
- RewriteInfo *info;
+ int current_varno,
+ new_varno;
+ int rt_length;
Query *sub_action;
Query **sub_action_ptr;
- int rt_length;
- info = (RewriteInfo *) palloc(sizeof(RewriteInfo));
- info->rt_index = rt_index;
- info->event = event;
- info->instead_flag = instead_flag;
- info->rule_action = (Query *) copyObject(rule_action);
- info->rule_qual = (Node *) copyObject(rule_qual);
- if (info->rule_action == NULL)
- {
- info->nothing = TRUE;
- return info;
- }
- info->nothing = FALSE;
- info->action = info->rule_action->commandType;
- info->current_varno = rt_index;
- rt_length = length(parsetree->rtable);
- info->new_varno = PRS2_NEW_VARNO + rt_length;
+ /*
+ * Make modifiable copies of rule action and qual (what we're passed are
+ * the stored versions in the relcache; don't touch 'em!).
+ */
+ rule_action = (Query *) copyObject(rule_action);
+ rule_qual = (Node *) copyObject(rule_qual);
+
+ /*
+ * Acquire necessary locks and fix any deleted JOIN RTE entries.
+ */
+ AcquireRewriteLocks(rule_action, false);
+ (void) acquireLocksOnSubLinks(rule_qual, NULL);
+
+ current_varno = rt_index;
+ rt_length = list_length(parsetree->rtable);
+ new_varno = PRS2_NEW_VARNO + rt_length;
/*
- * Adjust rule action and qual to offset its varnos, so that we can
- * merge its rtable into the main parsetree's rtable.
+ * Adjust rule action and qual to offset its varnos, so that we can merge
+ * its rtable with the main parsetree's rtable.
*
* If the rule action is an INSERT...SELECT, the OLD/NEW rtable entries
- * will be in the SELECT part, and we have to modify that rather than
- * the top-level INSERT (kluge!).
+ * will be in the SELECT part, and we have to modify that rather than the
+ * top-level INSERT (kluge!).
*/
- sub_action = getInsertSelectQuery(info->rule_action, &sub_action_ptr);
+ sub_action = getInsertSelectQuery(rule_action, &sub_action_ptr);
OffsetVarNodes((Node *) sub_action, rt_length, 0);
- OffsetVarNodes(info->rule_qual, rt_length, 0);
- /* but references to *OLD* should point at original rt_index */
+ OffsetVarNodes(rule_qual, rt_length, 0);
+ /* but references to OLD should point at original rt_index */
ChangeVarNodes((Node *) sub_action,
PRS2_OLD_VARNO + rt_length, rt_index, 0);
- ChangeVarNodes(info->rule_qual,
+ ChangeVarNodes(rule_qual,
PRS2_OLD_VARNO + rt_length, rt_index, 0);
/*
- * We want the main parsetree's rtable to end up as the concatenation
- * of its original contents plus those of all the relevant rule
- * actions. Also store same into all the rule_action rtables. Some of
- * the entries may be unused after we finish rewriting, but if we
- * tried to clean those out we'd have a much harder job to adjust RT
- * indexes in the query's Vars. It's OK to have unused RT entries,
- * since planner will ignore them.
+ * Generate expanded rtable consisting of main parsetree's rtable plus
+ * rule action's rtable; this becomes the complete rtable for the rule
+ * action. Some of the entries may be unused after we finish rewriting,
+ * but we leave them all in place for two reasons:
*
- * NOTE KLUGY HACK: we assume the parsetree rtable had at least one entry
- * to begin with (OK enough, else where'd the rule come from?).
- * Because of this, if multiple rules nconc() their rtable additions
- * onto parsetree->rtable, they'll all see the same rtable because
- * they all have the same list head pointer.
+ * We'd have a much harder job to adjust the query's varnos if we
+ * selectively removed RT entries.
+ *
+ * If the rule is INSTEAD, then the original query won't be executed at
+ * all, and so its rtable must be preserved so that the executor will do
+ * the correct permissions checks on it.
+ *
+ * RT entries that are not referenced in the completed jointree will be
+ * ignored by the planner, so they do not affect query semantics. But any
+ * permissions checks specified in them will be applied during executor
+ * startup (see ExecCheckRTEPerms()). This allows us to check that the
+ * caller has, say, insert-permission on a view, when the view is not
+ * semantically referenced at all in the resulting query.
+ *
+ * When a rule is not INSTEAD, the permissions checks done on its copied
+ * RT entries will be redundant with those done during execution of the
+ * original query, but we don't bother to treat that case differently.
+ *
+ * NOTE: because planner will destructively alter rtable, we must ensure
+ * that rule action's rtable is separate and shares no substructure with
+ * the main rtable. Hence do a deep copy here.
+ */
+ sub_action->rtable = list_concat((List *) copyObject(parsetree->rtable),
+ sub_action->rtable);
+
+ /*
+ * There could have been some SubLinks in parsetree's rtable, in which
+ * case we'd better mark the sub_action correctly.
*/
- parsetree->rtable = nconc(parsetree->rtable,
- sub_action->rtable);
- sub_action->rtable = parsetree->rtable;
+ if (parsetree->hasSubLinks && !sub_action->hasSubLinks)
+ {
+ ListCell *lc;
+
+ foreach(lc, parsetree->rtable)
+ {
+ RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
+
+ switch (rte->rtekind)
+ {
+ case RTE_FUNCTION:
+ sub_action->hasSubLinks =
+ checkExprHasSubLink(rte->funcexpr);
+ break;
+ case RTE_VALUES:
+ sub_action->hasSubLinks =
+ checkExprHasSubLink((Node *) rte->values_lists);
+ break;
+ default:
+ /* other RTE types don't contain bare expressions */
+ break;
+ }
+ if (sub_action->hasSubLinks)
+ break; /* no need to keep scanning rtable */
+ }
+ }
/*
* Each rule action's jointree should be the main parsetree's jointree
- * plus that rule's jointree, but usually *without* the original
- * rtindex that we're replacing (if present, which it won't be for
- * INSERT). Note that if the rule action refers to OLD, its jointree
- * will add a reference to rt_index. If the rule action doesn't refer
- * to OLD, but either the rule_qual or the user query quals do, then
- * we need to keep the original rtindex in the jointree to provide
- * data for the quals. We don't want the original rtindex to be
- * joined twice, however, so avoid keeping it if the rule action
- * mentions it.
- */
- if (sub_action->jointree != NULL)
+ * plus that rule's jointree, but usually *without* the original rtindex
+ * that we're replacing (if present, which it won't be for INSERT). Note
+ * that if the rule action refers to OLD, its jointree will add a
+ * reference to rt_index. If the rule action doesn't refer to OLD, but
+ * either the rule_qual or the user query quals do, then we need to keep
+ * the original rtindex in the jointree to provide data for the quals. We
+ * don't want the original rtindex to be joined twice, however, so avoid
+ * keeping it if the rule action mentions it.
+ *
+ * As above, the action's jointree must not share substructure with the
+ * main parsetree's.
+ */
+ if (sub_action->commandType != CMD_UTILITY)
{
bool keeporig;
List *newjointree;
+ Assert(sub_action->jointree != NULL);
keeporig = (!rangeTableEntry_used((Node *) sub_action->jointree,
rt_index, 0)) &&
- (rangeTableEntry_used(info->rule_qual, rt_index, 0) ||
- rangeTableEntry_used(parsetree->jointree->quals, rt_index, 0));
+ (rangeTableEntry_used(rule_qual, rt_index, 0) ||
+ rangeTableEntry_used(parsetree->jointree->quals, rt_index, 0));
newjointree = adjustJoinTreeList(parsetree, !keeporig, rt_index);
- sub_action->jointree->fromlist =
- nconc(newjointree, sub_action->jointree->fromlist);
- }
+ if (newjointree != NIL)
+ {
+ /*
+ * If sub_action is a setop, manipulating its jointree will do no
+ * good at all, because the jointree is dummy. (Perhaps someday
+ * we could push the joining and quals down to the member
+ * statements of the setop?)
+ */
+ if (sub_action->setOperations != NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
- /*
- * We copy the qualifications of the parsetree to the action and vice
- * versa. So force hasSubLinks if one of them has it. If this is not
- * right, the flag will get cleared later, but we mustn't risk having
- * it not set when it needs to be.
- */
- if (parsetree->hasSubLinks)
- sub_action->hasSubLinks = TRUE;
- else if (sub_action->hasSubLinks)
- parsetree->hasSubLinks = TRUE;
+ sub_action->jointree->fromlist =
+ list_concat(newjointree, sub_action->jointree->fromlist);
+
+ /*
+ * There could have been some SubLinks in newjointree, in which
+ * case we'd better mark the sub_action correctly.
+ */
+ if (parsetree->hasSubLinks && !sub_action->hasSubLinks)
+ sub_action->hasSubLinks =
+ checkExprHasSubLink((Node *) newjointree);
+ }
+ }
/*
- * Event Qualification forces copying of parsetree and splitting into
- * two queries one w/rule_qual, one w/NOT rule_qual. Also add user
- * query qual onto rule action
+ * Event Qualification forces copying of parsetree and splitting into two
+ * queries one w/rule_qual, one w/NOT rule_qual. Also add user query qual
+ * onto rule action
*/
- AddQual(sub_action, info->rule_qual);
+ AddQual(sub_action, rule_qual);
AddQual(sub_action, parsetree->jointree->quals);
*
* KLUGE ALERT: since ResolveNew returns a mutated copy, we can't just
* apply it to sub_action; we have to remember to update the sublink
- * inside info->rule_action, too.
+ * inside rule_action, too.
*/
- if (info->event == CMD_INSERT || info->event == CMD_UPDATE)
+ if ((event == CMD_INSERT || event == CMD_UPDATE) &&
+ sub_action->commandType != CMD_UTILITY)
{
sub_action = (Query *) ResolveNew((Node *) sub_action,
- info->new_varno,
+ new_varno,
0,
+ rt_fetch(new_varno,
+ sub_action->rtable),
parsetree->targetList,
- info->event,
- info->current_varno);
+ event,
+ current_varno,
+ NULL);
if (sub_action_ptr)
*sub_action_ptr = sub_action;
else
- info->rule_action = sub_action;
+ rule_action = sub_action;
}
- return info;
+ /*
+ * If rule_action has a RETURNING clause, then either throw it away if the
+ * triggering query has no RETURNING clause, or rewrite it to emit what
+ * the triggering query's RETURNING clause asks for. Throw an error if
+ * more than one rule has a RETURNING clause.
+ */
+ if (!parsetree->returningList)
+ rule_action->returningList = NIL;
+ else if (rule_action->returningList)
+ {
+ if (*returning_flag)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot have RETURNING lists in multiple rules")));
+ *returning_flag = true;
+ rule_action->returningList = (List *)
+ ResolveNew((Node *) parsetree->returningList,
+ parsetree->resultRelation,
+ 0,
+ rt_fetch(parsetree->resultRelation,
+ parsetree->rtable),
+ rule_action->returningList,
+ CMD_SELECT,
+ 0,
+ &rule_action->hasSubLinks);
+
+ /*
+ * There could have been some SubLinks in parsetree's returningList,
+ * in which case we'd better mark the rule_action correctly.
+ */
+ if (parsetree->hasSubLinks && !rule_action->hasSubLinks)
+ rule_action->hasSubLinks =
+ checkExprHasSubLink((Node *) rule_action->returningList);
+ }
+
+ return rule_action;
}
/*
* occurrence of the given rt_index as a top-level join item (we do not look
* for it within join items; this is OK because we are only expecting to find
* it as an UPDATE or DELETE target relation, which will be at the top level
- * of the join). Returns modified jointree list --- original list is not
- * changed.
+ * of the join). Returns modified jointree list --- this is a separate copy
+ * sharing no nodes with the original.
*/
static List *
adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
{
- List *newjointree = listCopy(parsetree->jointree->fromlist);
- List *jjt;
+ List *newjointree = copyObject(parsetree->jointree->fromlist);
+ ListCell *l;
if (removert)
{
- foreach(jjt, newjointree)
+ foreach(l, newjointree)
{
- RangeTblRef *rtr = lfirst(jjt);
+ RangeTblRef *rtr = lfirst(l);
- if (IsA(rtr, RangeTblRef) &&rtr->rtindex == rt_index)
+ if (IsA(rtr, RangeTblRef) &&
+ rtr->rtindex == rt_index)
{
- newjointree = lremove(rtr, newjointree);
+ newjointree = list_delete_ptr(newjointree, rtr);
+
+ /*
+ * foreach is safe because we exit loop after list_delete...
+ */
break;
}
}
}
+/*
+ * rewriteTargetListIU - rewrite INSERT/UPDATE targetlist into standard form
+ *
+ * This has the following responsibilities:
+ *
+ * 1. For an INSERT, add tlist entries to compute default values for any
+ * attributes that have defaults and are not assigned to in the given tlist.
+ * (We do not insert anything for default-less attributes, however. The
+ * planner will later insert NULLs for them, but there's no reason to slow
+ * down rewriter processing with extra tlist nodes.) Also, for both INSERT
+ * and UPDATE, replace explicit DEFAULT specifications with column default
+ * expressions.
+ *
+ * 2. For an UPDATE on a view, add tlist entries for any unassigned-to
+ * attributes, assigning them their old values. These will later get
+ * expanded to the output values of the view. (This is equivalent to what
+ * the planner's expand_targetlist() will do for UPDATE on a regular table,
+ * but it's more convenient to do it here while we still have easy access
+ * to the view's original RT index.)
+ *
+ * 3. Merge multiple entries for the same target attribute, or declare error
+ * if we can't. Multiple entries are only allowed for INSERT/UPDATE of
+ * portions of an array or record field, for example
+ * UPDATE table SET foo[2] = 42, foo[4] = 43;
+ * We can merge such operations into a single assignment op. Essentially,
+ * the expression we want to produce in this case is like
+ * foo = array_set(array_set(foo, 2, 42), 4, 43)
+ *
+ * 4. Sort the tlist into standard order: non-junk fields in order by resno,
+ * then junk fields (these in no particular order).
+ *
+ * We must do items 1,2,3 before firing rewrite rules, else rewritten
+ * references to NEW.foo will produce wrong or incomplete results. Item 4
+ * is not needed for rewriting, but will be needed by the planner, and we
+ * can do it essentially for free while handling the other items.
+ *
+ * If attrno_list isn't NULL, we return an additional output besides the
+ * rewritten targetlist: an integer list of the assigned-to attnums, in
+ * order of the original tlist's non-junk entries. This is needed for
+ * processing VALUES RTEs.
+ */
+static void
+rewriteTargetListIU(Query *parsetree, Relation target_relation,
+ List **attrno_list)
+{
+ CmdType commandType = parsetree->commandType;
+ TargetEntry **new_tles;
+ List *new_tlist = NIL;
+ List *junk_tlist = NIL;
+ Form_pg_attribute att_tup;
+ int attrno,
+ next_junk_attrno,
+ numattrs;
+ ListCell *temp;
+
+ if (attrno_list) /* initialize optional result list */
+ *attrno_list = NIL;
+
+ /*
+ * 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];
+
+ /* put attrno into attrno_list even if it's dropped */
+ if (attrno_list)
+ *attrno_list = lappend_int(*attrno_list, attrno);
+
+ /* 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,
+ -1,
+ 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, -1,
+ att_tup->atttypid,
+ COERCE_IMPLICIT_CAST,
+ -1,
+ false,
+ false);
+ }
+ }
+
+ if (new_expr)
+ new_tle = makeTargetEntry((Expr *) new_expr,
+ attrno,
+ pstrdup(NameStr(att_tup->attname)),
+ false);
+ }
+
+ /*
+ * For an UPDATE on a view, provide a dummy entry whenever there is
+ * no explicit assignment.
+ */
+ if (new_tle == NULL && commandType == CMD_UPDATE &&
+ target_relation->rd_rel->relkind == RELKIND_VIEW)
+ {
+ Node *new_expr;
+
+ new_expr = (Node *) makeVar(parsetree->resultRelation,
+ attrno,
+ att_tup->atttypid,
+ att_tup->atttypmod,
+ att_tup->attcollation,
+ 0);
+
+ 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, "cannot 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
+ * transformAssignedExpr().
+ */
+ exprtype = exprType(expr);
+
+ expr = coerce_to_target_type(NULL, /* no UNKNOWN params here */
+ expr, exprtype,
+ atttype, atttypmod,
+ COERCION_ASSIGNMENT,
+ COERCE_IMPLICIT_CAST,
+ -1);
+ if (expr == NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("column \"%s\" is of type %s"
+ " but default expression is of type %s",
+ NameStr(att_tup->attname),
+ format_type_be(atttype),
+ format_type_be(exprtype)),
+ errhint("You will need to rewrite or cast the expression.")));
+
+ return expr;
+}
+
+
+/* Does VALUES RTE contain any SetToDefault items? */
+static bool
+searchForDefault(RangeTblEntry *rte)
+{
+ ListCell *lc;
+
+ foreach(lc, rte->values_lists)
+ {
+ List *sublist = (List *) lfirst(lc);
+ ListCell *lc2;
+
+ foreach(lc2, sublist)
+ {
+ Node *col = (Node *) lfirst(lc2);
+
+ if (IsA(col, SetToDefault))
+ return true;
+ }
+ }
+ return false;
+}
+
+/*
+ * When processing INSERT ... VALUES with a VALUES RTE (ie, multiple VALUES
+ * lists), we have to replace any DEFAULT items in the VALUES lists with
+ * the appropriate default expressions. The other aspects of targetlist
+ * rewriting need be applied only to the query's targetlist proper.
+ *
+ * Note that we currently can't support subscripted or field assignment
+ * in the multi-VALUES case. The targetlist will contain simple Vars
+ * referencing the VALUES RTE, and therefore process_matched_tle() will
+ * reject any such attempt with "multiple assignments to same column".
+ */
+static void
+rewriteValuesRTE(RangeTblEntry *rte, Relation target_relation, List *attrnos)
+{
+ List *newValues;
+ ListCell *lc;
+
+ /*
+ * Rebuilding all the lists is a pretty expensive proposition in a big
+ * VALUES list, and it's a waste of time if there aren't any DEFAULT
+ * placeholders. So first scan to see if there are any.
+ */
+ if (!searchForDefault(rte))
+ return; /* nothing to do */
+
+ /* Check list lengths (we can assume all the VALUES sublists are alike) */
+ Assert(list_length(attrnos) == list_length(linitial(rte->values_lists)));
+
+ newValues = NIL;
+ foreach(lc, rte->values_lists)
+ {
+ List *sublist = (List *) lfirst(lc);
+ List *newList = NIL;
+ ListCell *lc2;
+ ListCell *lc3;
+
+ forboth(lc2, sublist, lc3, attrnos)
+ {
+ Node *col = (Node *) lfirst(lc2);
+ int attrno = lfirst_int(lc3);
+
+ if (IsA(col, SetToDefault))
+ {
+ Form_pg_attribute att_tup;
+ Node *new_expr;
+
+ att_tup = target_relation->rd_att->attrs[attrno - 1];
+
+ if (!att_tup->attisdropped)
+ new_expr = build_column_default(target_relation, attrno);
+ else
+ new_expr = NULL; /* force a NULL if dropped */
+
+ /*
+ * If there is no default (ie, default is effectively NULL),
+ * we've got to explicitly set the column to NULL.
+ */
+ if (!new_expr)
+ {
+ new_expr = (Node *) makeConst(att_tup->atttypid,
+ -1,
+ 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, -1,
+ att_tup->atttypid,
+ COERCE_IMPLICIT_CAST,
+ -1,
+ false,
+ false);
+ }
+ newList = lappend(newList, new_expr);
+ }
+ else
+ newList = lappend(newList, col);
+ }
+ newValues = lappend(newValues, newList);
+ }
+ rte->values_lists = newValues;
+}
+
+
+/*
+ * rewriteTargetListUD - rewrite UPDATE/DELETE targetlist as needed
+ *
+ * This function adds a "junk" TLE that is needed to allow the executor to
+ * find the original row for the update or delete. When the target relation
+ * is a regular table, the junk TLE emits the ctid attribute of the original
+ * row. When the target relation is a view, there is no ctid, so we instead
+ * emit a whole-row Var that will contain the "old" values of the view row.
+ *
+ * For UPDATE queries, this is applied after rewriteTargetListIU. The
+ * ordering isn't actually critical at the moment.
+ */
+static void
+rewriteTargetListUD(Query *parsetree, RangeTblEntry *target_rte,
+ Relation target_relation)
+{
+ Var *var;
+ const char *attrname;
+ TargetEntry *tle;
+
+ if (target_relation->rd_rel->relkind == RELKIND_RELATION)
+ {
+ /*
+ * Emit CTID so that executor can find the row to update or delete.
+ */
+ var = makeVar(parsetree->resultRelation,
+ SelfItemPointerAttributeNumber,
+ TIDOID,
+ -1,
+ InvalidOid,
+ 0);
+
+ attrname = "ctid";
+ }
+ else
+ {
+ /*
+ * Emit whole-row Var so that executor will have the "old" view row
+ * to pass to the INSTEAD OF trigger.
+ */
+ var = makeWholeRowVar(target_rte,
+ parsetree->resultRelation,
+ 0);
+
+ attrname = "wholerow";
+ }
+
+ tle = makeTargetEntry((Expr *) var,
+ list_length(parsetree->targetList) + 1,
+ pstrdup(attrname),
+ true);
+
+ parsetree->targetList = lappend(parsetree->targetList, tle);
+}
+
+
/*
* matchLocks -
* match the list of locks and returns the matching rules
int varno,
Query *parsetree)
{
- List *real_locks = NIL;
+ List *matching_locks = NIL;
int nlocks;
int i;
- Assert(rulelocks != NULL); /* we get called iff there is some lock */
- Assert(parsetree != NULL);
+ if (rulelocks == NULL)
+ return NIL;
if (parsetree->commandType != CMD_SELECT)
{
{
RewriteRule *oneLock = rulelocks->rules[i];
+ /*
+ * Suppress ON INSERT/UPDATE/DELETE rules that are disabled or
+ * configured to not fire during the current sessions replication
+ * role. ON SELECT rules will always be applied in order to keep views
+ * working even in LOCAL or REPLICA role.
+ */
+ if (oneLock->event != CMD_SELECT)
+ {
+ if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
+ {
+ if (oneLock->enabled == RULE_FIRES_ON_ORIGIN ||
+ oneLock->enabled == RULE_DISABLED)
+ continue;
+ }
+ else /* ORIGIN or LOCAL ROLE */
+ {
+ if (oneLock->enabled == RULE_FIRES_ON_REPLICA ||
+ oneLock->enabled == RULE_DISABLED)
+ continue;
+ }
+ }
+
if (oneLock->event == event)
{
if (parsetree->commandType != CMD_SELECT ||
rangeTableEntry_used((Node *) parsetree, varno, 0) :
attribute_used((Node *) parsetree,
varno, oneLock->attrno, 0)))
- real_locks = lappend(real_locks, oneLock);
+ matching_locks = lappend(matching_locks, oneLock);
}
}
- return real_locks;
+ return matching_locks;
}
+/*
+ * ApplyRetrieveRule - expand an ON SELECT rule
+ */
static Query *
ApplyRetrieveRule(Query *parsetree,
RewriteRule *rule,
int rt_index,
bool relation_level,
Relation relation,
- bool relIsUsed)
+ List *activeRIRs,
+ bool forUpdatePushedDown)
{
Query *rule_action;
RangeTblEntry *rte,
*subrte;
+ RowMarkClause *rc;
- if (length(rule->actions) != 1)
- elog(ERROR, "ApplyRetrieveRule: expected just one rule action");
+ if (list_length(rule->actions) != 1)
+ elog(ERROR, "expected just one rule action");
if (rule->qual != NULL)
- elog(ERROR, "ApplyRetrieveRule: can't handle qualified ON SELECT rule");
+ elog(ERROR, "cannot handle qualified ON SELECT rule");
if (!relation_level)
- elog(ERROR, "ApplyRetrieveRule: can't handle per-attribute ON SELECT rule");
+ elog(ERROR, "cannot handle per-attribute ON SELECT rule");
+
+ if (rt_index == parsetree->resultRelation)
+ {
+ /*
+ * We have a view as the result relation of the query, and it wasn't
+ * rewritten by any rule. This case is supported if there is an
+ * INSTEAD OF trigger that will trap attempts to insert/update/delete
+ * view rows. The executor will check that; for the moment just plow
+ * ahead. We have two cases:
+ *
+ * For INSERT, we needn't do anything. The unmodified RTE will serve
+ * fine as the result relation.
+ *
+ * For UPDATE/DELETE, we need to expand the view so as to have source
+ * data for the operation. But we also need an unmodified RTE to
+ * serve as the target. So, copy the RTE and add the copy to the
+ * rangetable. Note that the copy does not get added to the jointree.
+ * Also note that there's a hack in fireRIRrules to avoid calling
+ * this function again when it arrives at the copied RTE.
+ */
+ if (parsetree->commandType == CMD_INSERT)
+ return parsetree;
+ else if (parsetree->commandType == CMD_UPDATE ||
+ parsetree->commandType == CMD_DELETE)
+ {
+ RangeTblEntry *newrte;
+
+ rte = rt_fetch(rt_index, parsetree->rtable);
+ newrte = copyObject(rte);
+ parsetree->rtable = lappend(parsetree->rtable, newrte);
+ parsetree->resultRelation = list_length(parsetree->rtable);
+
+ /*
+ * There's no need to do permissions checks twice, so wipe out
+ * the permissions info for the original RTE (we prefer to keep
+ * the bits set on the result RTE).
+ */
+ rte->requiredPerms = 0;
+ rte->checkAsUser = InvalidOid;
+ rte->selectedCols = NULL;
+ rte->modifiedCols = NULL;
+
+ /*
+ * For the most part, Vars referencing the view should remain as
+ * they are, meaning that they implicitly represent OLD values.
+ * But in the RETURNING list if any, we want such Vars to
+ * represent NEW values, so change them to reference the new RTE.
+ *
+ * Since ChangeVarNodes scribbles on the tree in-place, copy the
+ * RETURNING list first for safety.
+ */
+ parsetree->returningList = copyObject(parsetree->returningList);
+ ChangeVarNodes((Node *) parsetree->returningList, rt_index,
+ parsetree->resultRelation, 0);
+
+ /* Now, continue with expanding the original view RTE */
+ }
+ else
+ elog(ERROR, "unrecognized commandType: %d",
+ (int) parsetree->commandType);
+ }
+
+ /*
+ * If FOR UPDATE/SHARE of view, be sure we get right initial lock on the
+ * relations it references.
+ */
+ rc = get_parse_rowmark(parsetree, rt_index);
+ forUpdatePushedDown |= (rc != NULL);
/*
- * Make a modifiable copy of the view query, and recursively expand
- * any view references inside it.
+ * Make a modifiable copy of the view query, and acquire needed locks on
+ * the relations it mentions.
*/
- rule_action = copyObject(lfirst(rule->actions));
+ rule_action = copyObject(linitial(rule->actions));
- rule_action = fireRIRrules(rule_action);
+ AcquireRewriteLocks(rule_action, forUpdatePushedDown);
+
+ /*
+ * Recursively expand any view references inside the view.
+ */
+ rule_action = fireRIRrules(rule_action, activeRIRs, forUpdatePushedDown);
/*
- * VIEWs are really easy --- just plug the view query in as a
- * subselect, replacing the relation's original RTE.
+ * Now, plug the view query in as a subselect, replacing the relation's
+ * original RTE.
*/
rte = rt_fetch(rt_index, parsetree->rtable);
- rte->relname = NULL;
+ 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.
+ * 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->requiredPerms = rte->requiredPerms;
+ subrte->checkAsUser = rte->checkAsUser;
+ subrte->selectedCols = rte->selectedCols;
+ subrte->modifiedCols = rte->modifiedCols;
- rte->checkForRead = false; /* no permission check on subquery itself */
- rte->checkForWrite = false;
+ rte->requiredPerms = 0; /* no permission check on subquery itself */
+ rte->checkAsUser = InvalidOid;
+ rte->selectedCols = NULL;
+ rte->modifiedCols = NULL;
/*
- * FOR UPDATE of view?
+ * If FOR UPDATE/SHARE of view, mark all the contained tables as implicit
+ * FOR UPDATE/SHARE, the same as the parser would have done if the view's
+ * subquery had been written out explicitly.
+ *
+ * Note: we don't consider forUpdatePushedDown here; such marks will be
+ * made by recursing from the upper level in markQueryForLocking.
*/
- 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);
- }
+ if (rc != NULL)
+ markQueryForLocking(rule_action, (Node *) rule_action->jointree,
+ rc->forUpdate, rc->noWait, true);
return parsetree;
}
/*
- * Recursively mark all relations used by a view as FOR UPDATE.
+ * 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 transformForUpdate() routine.
+ * NB: this must agree with the parser's transformLockingClause() routine.
+ * However, unlike the parser we have to be careful not to mark a view's
+ * OLD and NEW rels for updating. The best way to handle that seems to be
+ * to scan the jointree to determine which rels are used.
*/
static void
-markQueryForUpdate(Query *qry, bool skipOldNew)
+markQueryForLocking(Query *qry, Node *jtnode,
+ bool forUpdate, bool noWait, bool pushedDown)
{
- Index rti = 0;
- List *l;
-
- foreach(l, qry->rtable)
+ if (jtnode == NULL)
+ return;
+ if (IsA(jtnode, RangeTblRef))
{
- RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
+ int rti = ((RangeTblRef *) jtnode)->rtindex;
+ RangeTblEntry *rte = rt_fetch(rti, qry->rtable);
- 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->subquery)
+ if (rte->rtekind == RTE_RELATION)
{
- /* FOR UPDATE of subquery is propagated to subquery's rels */
- markQueryForUpdate(rte->subquery, false);
+ /* ignore foreign tables */
+ if (get_rel_relkind(rte->relid) != RELKIND_FOREIGN_TABLE)
+ {
+ applyLockingClause(qry, rti, forUpdate, noWait, pushedDown);
+ rte->requiredPerms |= ACL_SELECT_FOR_UPDATE;
+ }
}
- else
+ else if (rte->rtekind == RTE_SUBQUERY)
{
- if (!intMember(rti, qry->rowMarks))
- qry->rowMarks = lappendi(qry->rowMarks, rti);
- rte->checkForWrite = true;
+ applyLockingClause(qry, rti, forUpdate, noWait, pushedDown);
+ /* FOR UPDATE/SHARE of subquery is propagated to subquery's rels */
+ markQueryForLocking(rte->subquery, (Node *) rte->subquery->jointree,
+ forUpdate, noWait, true);
}
+ /* other RTE types are unaffected by FOR UPDATE */
+ }
+ else if (IsA(jtnode, FromExpr))
+ {
+ FromExpr *f = (FromExpr *) jtnode;
+ ListCell *l;
+
+ foreach(l, f->fromlist)
+ markQueryForLocking(qry, lfirst(l), forUpdate, noWait, pushedDown);
+ }
+ else if (IsA(jtnode, JoinExpr))
+ {
+ JoinExpr *j = (JoinExpr *) jtnode;
+
+ markQueryForLocking(qry, j->larg, forUpdate, noWait, pushedDown);
+ markQueryForLocking(qry, j->rarg, forUpdate, noWait, pushedDown);
}
+ else
+ elog(ERROR, "unrecognized node type: %d",
+ (int) nodeTag(jtnode));
}
* the SubLink's subselect link with the possibly-rewritten subquery.
*/
static bool
-fireRIRonSubLink(Node *node, void *context)
+fireRIRonSubLink(Node *node, List *activeRIRs)
{
if (node == NULL)
return false;
SubLink *sub = (SubLink *) node;
/* Do what we came for */
- sub->subselect = (Node *) fireRIRrules((Query *) (sub->subselect));
+ sub->subselect = (Node *) fireRIRrules((Query *) sub->subselect,
+ activeRIRs, false);
/* Fall through to process lefthand args of SubLink */
}
/*
- * Do NOT recurse into Query nodes, because fireRIRrules already
- * processed subselects of subselects for us.
+ * Do NOT recurse into Query nodes, because fireRIRrules already processed
+ * subselects of subselects for us.
*/
return expression_tree_walker(node, fireRIRonSubLink,
- (void *) context);
+ (void *) activeRIRs);
}
* Apply all RIR rules on each rangetable entry in a query
*/
static Query *
-fireRIRrules(Query *parsetree)
+fireRIRrules(Query *parsetree, List *activeRIRs, bool forUpdatePushedDown)
{
+ int origResultRelation = parsetree->resultRelation;
int rt_index;
+ ListCell *lc;
/*
- * don't try to convert this into a foreach loop, because rtable list
- * can get changed each time through...
+ * don't try to convert this into a foreach loop, because rtable list can
+ * get changed each time through...
*/
rt_index = 0;
- while (rt_index < length(parsetree->rtable))
+ while (rt_index < list_length(parsetree->rtable))
{
RangeTblEntry *rte;
Relation rel;
List *locks;
RuleLock *rules;
RewriteRule *rule;
- LOCKMODE lockmode;
- bool relIsUsed;
int i;
- List *l;
++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
+ * 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->subquery)
+ if (rte->rtekind == RTE_SUBQUERY)
{
- rte->subquery = fireRIRrules(rte->subquery);
+ rte->subquery = fireRIRrules(rte->subquery, activeRIRs,
+ (forUpdatePushedDown ||
+ get_parse_rowmark(parsetree, rt_index) != NULL));
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.
+ * 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)
+ if (rt_index != parsetree->resultRelation &&
+ !rangeTableEntry_used((Node *) parsetree, rt_index, 0))
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.
+ * Also, if this is a new result relation introduced by
+ * ApplyRetrieveRule, we don't want to do anything more with it.
*/
- if (rt_index == parsetree->resultRelation)
- lockmode = NoLock;
- else if (intMember(rt_index, parsetree->rowMarks))
- lockmode = RowShareLock;
- else
- lockmode = AccessShareLock;
+ if (rt_index == parsetree->resultRelation &&
+ rt_index != origResultRelation)
+ continue;
- rel = heap_openr(rte->relname, lockmode);
+ /*
+ * 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;
}
-
- /*
- * Collect the RIR rules that we must apply
- */
locks = NIL;
for (i = 0; i < rules->numLocks; i++)
{
}
/*
- * Now apply them
+ * If we found any, apply them --- but first check for recursion!
*/
- foreach(l, locks)
+ if (locks != NIL)
{
- rule = lfirst(l);
+ 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);
- parsetree = ApplyRetrieveRule(parsetree,
- rule,
- rt_index,
- rule->attrno == -1,
- rel,
- relIsUsed);
+ foreach(l, locks)
+ {
+ rule = lfirst(l);
+
+ parsetree = ApplyRetrieveRule(parsetree,
+ rule,
+ rt_index,
+ rule->attrno == -1,
+ rel,
+ activeRIRs,
+ forUpdatePushedDown);
+ }
+
+ activeRIRs = list_delete_first(activeRIRs);
}
heap_close(rel, NoLock);
}
- /*
- * Recurse into sublink subqueries, too.
- */
- if (parsetree->hasSubLinks)
- query_tree_walker(parsetree, fireRIRonSubLink, NULL,
- false /* already handled the ones in rtable */ );
+ /* Recurse into subqueries in WITH */
+ foreach(lc, parsetree->cteList)
+ {
+ CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
+
+ cte->ctequery = (Node *)
+ fireRIRrules((Query *) cte->ctequery, activeRIRs, false);
+ }
/*
- * 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...)
+ * Recurse into sublink subqueries, too. But we already did the ones in
+ * the rtable and cteList.
*/
- 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);
+ query_tree_walker(parsetree, fireRIRonSubLink, (void *) activeRIRs,
+ QTW_IGNORE_RC_SUBQUERIES);
return parsetree;
}
/*
- * idea is to fire regular rules first, then qualified instead
- * rules and unqualified instead rules last. Any lemming is counted for.
- */
-static List *
-orderRules(List *locks)
-{
- List *regular = NIL;
- List *instead_rules = NIL;
- List *instead_qualified = NIL;
- List *i;
-
- foreach(i, locks)
- {
- RewriteRule *rule_lock = (RewriteRule *) lfirst(i);
-
- if (rule_lock->isInstead)
- {
- if (rule_lock->qual == NULL)
- instead_rules = lappend(instead_rules, rule_lock);
- else
- instead_qualified = lappend(instead_qualified, rule_lock);
- }
- else
- regular = lappend(regular, rule_lock);
- }
- return nconc(nconc(regular, instead_qualified), instead_rules);
-}
-
-
-/*
- * Modify the given query by adding 'AND NOT rule_qual' to its qualification.
- * This is used to generate suitable "else clauses" for conditional INSTEAD
- * rules.
+ * 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
* of the related entries in the query's own targetlist.
*/
static Query *
-CopyAndAddQual(Query *parsetree,
- Node *rule_qual,
- int rt_index,
- CmdType event)
+CopyAndAddInvertedQual(Query *parsetree,
+ Node *rule_qual,
+ int rt_index,
+ CmdType event)
{
- Query *new_tree = (Query *) copyObject(parsetree);
+ /* 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 */
new_qual = ResolveNew(new_qual,
PRS2_NEW_VARNO,
0,
+ rt_fetch(rt_index, parsetree->rtable),
parsetree->targetList,
event,
- rt_index);
+ rt_index,
+ &parsetree->hasSubLinks);
/* And attach the fixed qual */
- AddNotQual(new_tree, new_qual);
+ AddInvertedQual(parsetree, new_qual);
- return new_tree;
+ return parsetree;
}
-
/*
* fireRules -
* Iterate through rule locks applying rules.
- * All rules create their own parsetrees. Instead rules
- * with rule qualification save the original parsetree
- * and add their negated qualification to it. Real instead
- * rules finally throw away the original parsetree.
*
- * remember: reality is for dead birds -- glass
+ * Input arguments:
+ * parsetree - original query
+ * rt_index - RT index of result relation in original query
+ * event - type of rule event
+ * locks - list of rules to fire
+ * Output arguments:
+ * *instead_flag - set TRUE if any unqualified INSTEAD rule is found
+ * (must be initialized to FALSE)
+ * *returning_flag - set TRUE if we rewrite RETURNING clause in any rule
+ * (must be initialized to FALSE)
+ * *qual_product - filled with modified original query if any qualified
+ * INSTEAD rule is found (must be initialized to NULL)
+ * Return value:
+ * list of rule actions adjusted for use with this query
*
+ * Qualified INSTEAD rules generate their action with the qualification
+ * condition added. They also generate a modified version of the original
+ * query with the negated qualification added, so that it will run only for
+ * rows that the qualified action doesn't act on. (If there are multiple
+ * qualified INSTEAD rules, we AND all the negated quals onto a single
+ * modified original query.) We won't execute the original, unmodified
+ * query if we find either qualified or unqualified INSTEAD rules. If
+ * we find both, the modified original query is discarded too.
*/
static List *
fireRules(Query *parsetree,
int rt_index,
CmdType event,
- bool *instead_flag,
List *locks,
- List **qual_products)
+ bool *instead_flag,
+ bool *returning_flag,
+ Query **qual_product)
{
List *results = NIL;
- List *i;
-
- /* choose rule to fire from list of rules */
- if (locks == NIL)
- return NIL;
+ ListCell *l;
- locks = orderRules(locks); /* real instead rules last */
-
- foreach(i, locks)
+ foreach(l, locks)
{
- RewriteRule *rule_lock = (RewriteRule *) lfirst(i);
- Node *event_qual;
- List *actions;
- List *r;
-
- /* multiple rule action time */
- *instead_flag = rule_lock->isInstead;
- event_qual = rule_lock->qual;
- actions = rule_lock->actions;
+ RewriteRule *rule_lock = (RewriteRule *) lfirst(l);
+ Node *event_qual = rule_lock->qual;
+ List *actions = rule_lock->actions;
+ QuerySource qsrc;
+ ListCell *r;
- if (event_qual != NULL && *instead_flag)
+ /* Determine correct QuerySource value for actions */
+ if (rule_lock->isInstead)
{
- Query *qual_product;
+ 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 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_products
- * so deepRewriteQuery() can add it to the query
+ 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 (*qual_products == NIL)
- qual_product = parsetree;
- else
- qual_product = (Query *) lfirst(*qual_products);
-
- qual_product = CopyAndAddQual(qual_product,
- event_qual,
- rt_index,
- event);
-
- *qual_products = makeList1(qual_product);
+ 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);
- RewriteInfo *info;
if (rule_action->commandType == CMD_NOTHING)
continue;
- info = gatherRewriteMeta(parsetree, rule_action, event_qual,
- rt_index, event, *instead_flag);
-
- /* handle escapable cases, or those handled by other code */
- if (info->nothing)
- {
- if (*instead_flag)
- return NIL;
- else
- continue;
- }
+ rule_action = rewriteRuleAction(parsetree, rule_action,
+ event_qual, rt_index, event,
+ returning_flag);
- results = lappend(results, info->rule_action);
+ rule_action->querySource = qsrc;
+ rule_action->canSetTag = false; /* might change later */
- pfree(info);
+ results = lappend(results, rule_action);
}
-
- /* ----------
- * If this was an unqualified instead rule,
- * throw away an eventually saved 'default' parsetree
- * ----------
- */
- if (event_qual == NULL && *instead_flag)
- *qual_products = NIL;
}
+
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, bool *instead_flag, List **qual_products)
+RewriteQuery(Query *parsetree, List *rewrite_events)
{
- CmdType event;
- List *product_queries = NIL;
- int result_relation;
- RangeTblEntry *rt_entry;
- Relation rt_entry_relation;
- RuleLock *rt_entry_locks;
-
- Assert(parsetree != NULL);
-
- event = parsetree->commandType;
+ CmdType event = parsetree->commandType;
+ bool instead = false;
+ bool returning = false;
+ Query *qual_product = NULL;
+ List *rewritten = NIL;
/*
- * SELECT rules are handled later when we have all the queries that
- * should get executed
+ * If the statement is an insert, update, or delete, adjust its targetlist
+ * as needed, and then fire INSERT/UPDATE/DELETE rules on it.
+ *
+ * SELECT rules are handled later when we have all the queries that should
+ * get executed. Also, utilities aren't rewritten at all (do we still
+ * need that check?)
*/
- if (event == CMD_SELECT)
- return NIL;
+ if (event != CMD_SELECT && event != CMD_UTILITY)
+ {
+ int result_relation;
+ RangeTblEntry *rt_entry;
+ Relation rt_entry_relation;
+ List *locks;
- /*
- * Utilities aren't rewritten at all - why is this here?
- */
- if (event == CMD_UTILITY)
- return NIL;
+ result_relation = parsetree->resultRelation;
+ Assert(result_relation != 0);
+ rt_entry = rt_fetch(result_relation, parsetree->rtable);
+ Assert(rt_entry->rtekind == RTE_RELATION);
- /*
- * the statement is an update, insert or delete - fire rules on it.
- */
- result_relation = parsetree->resultRelation;
- Assert(result_relation != 0);
- rt_entry = rt_fetch(result_relation, parsetree->rtable);
+ /*
+ * 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);
- /*
- * 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_openr(rt_entry->relname, RowExclusiveLock);
+ /*
+ * Rewrite the targetlist as needed for the command type.
+ */
+ if (event == CMD_INSERT)
+ {
+ RangeTblEntry *values_rte = NULL;
- rt_entry_locks = rt_entry_relation->rd_rules;
+ /*
+ * If it's an INSERT ... VALUES (...), (...), ... there will be a
+ * single RTE for the VALUES targetlists.
+ */
+ if (list_length(parsetree->jointree->fromlist) == 1)
+ {
+ RangeTblRef *rtr = (RangeTblRef *) linitial(parsetree->jointree->fromlist);
- if (rt_entry_locks != NULL)
- {
- List *locks = matchLocks(event, rt_entry_locks,
- result_relation, parsetree);
+ if (IsA(rtr, RangeTblRef))
+ {
+ RangeTblEntry *rte = rt_fetch(rtr->rtindex,
+ parsetree->rtable);
- product_queries = fireRules(parsetree,
- result_relation,
- event,
- instead_flag,
- locks,
- qual_products);
- }
+ if (rte->rtekind == RTE_VALUES)
+ values_rte = rte;
+ }
+ }
- heap_close(rt_entry_relation, NoLock); /* keep lock! */
+ if (values_rte)
+ {
+ List *attrnos;
- return product_queries;
-}
+ /* Process the main targetlist ... */
+ rewriteTargetListIU(parsetree, rt_entry_relation, &attrnos);
+ /* ... and the VALUES expression lists */
+ rewriteValuesRTE(values_rte, rt_entry_relation, attrnos);
+ }
+ else
+ {
+ /* Process just the main targetlist */
+ rewriteTargetListIU(parsetree, rt_entry_relation, NULL);
+ }
+ }
+ else if (event == CMD_UPDATE)
+ {
+ rewriteTargetListIU(parsetree, rt_entry_relation, NULL);
+ rewriteTargetListUD(parsetree, rt_entry, rt_entry_relation);
+ }
+ else if (event == CMD_DELETE)
+ {
+ rewriteTargetListUD(parsetree, rt_entry, rt_entry_relation);
+ }
+ else
+ elog(ERROR, "unrecognized commandType: %d", (int) event);
+ /*
+ * Collect and apply the appropriate rules.
+ */
+ locks = matchLocks(event, rt_entry_relation->rd_rules,
+ result_relation, parsetree);
-/*
- * to avoid infinite recursion, we restrict the number of times a query
- * can be rewritten. Detecting cycles is left for the reader as an exercise.
- */
-#ifndef REWRITE_INVOKE_MAX
-#define REWRITE_INVOKE_MAX 10
-#endif
+ if (locks != NIL)
+ {
+ List *product_queries;
+
+ product_queries = fireRules(parsetree,
+ result_relation,
+ event,
+ locks,
+ &instead,
+ &returning,
+ &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;
-static int numQueryRewriteInvoked = 0;
+ 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))));
+ }
-/*
- * deepRewriteQuery -
- * rewrites the query and apply the rules again on the queries rewritten
- */
-static List *
-deepRewriteQuery(Query *parsetree)
-{
- List *n;
- List *rewritten = NIL;
- List *result;
- bool instead;
- List *qual_products = NIL;
+ rev = (rewrite_event *) palloc(sizeof(rewrite_event));
+ rev->relation = RelationGetRelid(rt_entry_relation);
+ rev->event = event;
+ rewrite_events = lcons(rev, rewrite_events);
- if (++numQueryRewriteInvoked > REWRITE_INVOKE_MAX)
- {
- elog(ERROR, "query rewritten %d times, may contain cycles",
- numQueryRewriteInvoked - 1);
- }
+ foreach(n, product_queries)
+ {
+ Query *pt = (Query *) lfirst(n);
+ List *newstuff;
- instead = FALSE;
- result = RewriteQuery(parsetree, &instead, &qual_products);
+ newstuff = RewriteQuery(pt, rewrite_events);
+ rewritten = list_concat(rewritten, newstuff);
+ }
- foreach(n, result)
- {
- Query *pt = lfirst(n);
- List *newstuff;
+ rewrite_events = list_delete_first(rewrite_events);
+ }
+ }
- newstuff = deepRewriteQuery(pt);
- if (newstuff != NIL)
- rewritten = nconc(rewritten, newstuff);
- }
+ /*
+ * If there is an INSTEAD, and the original query has a RETURNING, we
+ * have to have found a RETURNING in the rule(s), else fail. (Because
+ * DefineQueryRewrite only allows RETURNING in unconditional INSTEAD
+ * rules, there's no need to worry whether the substituted RETURNING
+ * will actually be executed --- it must be.)
+ */
+ if ((instead || qual_product != NULL) &&
+ parsetree->returningList &&
+ !returning)
+ {
+ switch (event)
+ {
+ case CMD_INSERT:
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot perform INSERT RETURNING on relation \"%s\"",
+ RelationGetRelationName(rt_entry_relation)),
+ errhint("You need an unconditional ON INSERT DO INSTEAD rule with a RETURNING clause.")));
+ break;
+ case CMD_UPDATE:
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot perform UPDATE RETURNING on relation \"%s\"",
+ RelationGetRelationName(rt_entry_relation)),
+ errhint("You need an unconditional ON UPDATE DO INSTEAD rule with a RETURNING clause.")));
+ break;
+ case CMD_DELETE:
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot perform DELETE RETURNING on relation \"%s\"",
+ RelationGetRelationName(rt_entry_relation)),
+ errhint("You need an unconditional ON DELETE DO INSTEAD rule with a RETURNING clause.")));
+ break;
+ default:
+ elog(ERROR, "unrecognized commandType: %d",
+ (int) event);
+ break;
+ }
+ }
- /* ----------
- * qual_products are the original query with the negated
- * rule qualification of an instead rule
- * ----------
- */
- if (qual_products != NIL)
- rewritten = nconc(rewritten, qual_products);
+ heap_close(rt_entry_relation, NoLock);
+ }
- /* ----------
- * The original query is appended last (if no "instead" rule)
- * 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 execution makes the deleted (and
- * maybe the updated) tuples disappear so the scans
+ /*
+ * 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)
- rewritten = lappend(rewritten, parsetree);
+ {
+ 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;
}
-/*
- * QueryRewriteOne -
- * rewrite one query
- */
-static List *
-QueryRewriteOne(Query *parsetree)
-{
- numQueryRewriteInvoked = 0;
-
- /*
- * take a deep breath and apply all the rewrite rules - ay
- */
- return deepRewriteQuery(parsetree);
-}
-
-
/*
* 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.
+ * 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;
- List *l;
+ List *results;
+ ListCell *l;
+ CmdType origCmdType;
+ bool foundOriginalQuery;
+ Query *lastInstead;
/*
* Step 1
*
* Apply all non-SELECT rules possibly getting 0 or many queries
*/
- querylist = QueryRewriteOne(parsetree);
+ querylist = RewriteQuery(parsetree, NIL);
/*
* Step 2
*
* Apply all the RIR rules on each query
*/
+ results = NIL;
foreach(l, querylist)
{
Query *query = (Query *) lfirst(l);
- query = fireRIRrules(query);
+ query = fireRIRrules(query, NIL, false);
+ results = lappend(results, query);
+ }
- /*
- * If the query target was rewritten as a view, complain.
- */
- if (query->resultRelation)
- {
- RangeTblEntry *rte = rt_fetch(query->resultRelation,
- query->rtable);
+ /*
+ * 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;
- if (rte->subquery)
- {
- switch (query->commandType)
- {
- case CMD_INSERT:
- elog(ERROR, "Cannot insert into a view without an appropriate rule");
- break;
- case CMD_UPDATE:
- elog(ERROR, "Cannot update a view without an appropriate rule");
- break;
- case CMD_DELETE:
- elog(ERROR, "Cannot delete from a view without an appropriate rule");
- break;
- default:
- elog(ERROR, "QueryRewrite: unexpected commandType %d",
- (int) query->commandType);
- break;
- }
- }
- }
+ foreach(l, results)
+ {
+ Query *query = (Query *) lfirst(l);
- results = lappend(results, query);
+ 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;
}