mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-20 05:13:23 +02:00
1966 lines
57 KiB
C
1966 lines
57 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* rewriteHandler.c
|
|
* Primary module of query rewriter.
|
|
*
|
|
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* IDENTIFICATION
|
|
* $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.193 2010/01/02 16:57:51 momjian Exp $
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#include "postgres.h"
|
|
|
|
#include "access/heapam.h"
|
|
#include "catalog/pg_type.h"
|
|
#include "nodes/makefuncs.h"
|
|
#include "nodes/nodeFuncs.h"
|
|
#include "parser/analyze.h"
|
|
#include "parser/parse_coerce.h"
|
|
#include "parser/parsetree.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 bool acquireLocksOnSubLinks(Node *node, void *context);
|
|
static Query *rewriteRuleAction(Query *parsetree,
|
|
Query *rule_action,
|
|
Node *rule_qual,
|
|
int rt_index,
|
|
CmdType event,
|
|
bool *returning_flag);
|
|
static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
|
|
static void rewriteTargetList(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 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, List *activeRIRs,
|
|
bool forUpdatePushedDown);
|
|
|
|
|
|
/*
|
|
* 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.)
|
|
*/
|
|
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 *returning_flag)
|
|
{
|
|
int current_varno,
|
|
new_varno;
|
|
int rt_length;
|
|
Query *sub_action;
|
|
Query **sub_action_ptr;
|
|
|
|
/*
|
|
* Make modifiable copies of rule action and qual (what we're passed are
|
|
* the stored versions in the relcache; don't touch 'em!).
|
|
*/
|
|
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 with the main parsetree's rtable.
|
|
*
|
|
* If the rule action is an INSERT...SELECT, the OLD/NEW rtable entries
|
|
* will be in the SELECT part, and we have to modify that rather than the
|
|
* top-level INSERT (kluge!).
|
|
*/
|
|
sub_action = getInsertSelectQuery(rule_action, &sub_action_ptr);
|
|
|
|
OffsetVarNodes((Node *) sub_action, rt_length, 0);
|
|
OffsetVarNodes(rule_qual, rt_length, 0);
|
|
/* but references to OLD should point at original rt_index */
|
|
ChangeVarNodes((Node *) sub_action,
|
|
PRS2_OLD_VARNO + rt_length, rt_index, 0);
|
|
ChangeVarNodes(rule_qual,
|
|
PRS2_OLD_VARNO + rt_length, rt_index, 0);
|
|
|
|
/*
|
|
* 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:
|
|
*
|
|
* 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.
|
|
*/
|
|
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.
|
|
*
|
|
* As above, the action's jointree must not share substructure with the
|
|
* main parsetree's.
|
|
*/
|
|
if (sub_action->commandType != CMD_UTILITY)
|
|
{
|
|
bool keeporig;
|
|
List *newjointree;
|
|
|
|
Assert(sub_action->jointree != NULL);
|
|
keeporig = (!rangeTableEntry_used((Node *) sub_action->jointree,
|
|
rt_index, 0)) &&
|
|
(rangeTableEntry_used(rule_qual, rt_index, 0) ||
|
|
rangeTableEntry_used(parsetree->jointree->quals, rt_index, 0));
|
|
newjointree = adjustJoinTreeList(parsetree, !keeporig, rt_index);
|
|
if (newjointree != NIL)
|
|
{
|
|
/*
|
|
* If sub_action is a setop, manipulating its jointree will do no
|
|
* good at all, because the jointree is dummy. (Perhaps someday
|
|
* we could push the joining and quals down to the member
|
|
* statements of the setop?)
|
|
*/
|
|
if (sub_action->setOperations != NULL)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
|
|
|
|
sub_action->jointree->fromlist =
|
|
list_concat(newjointree, sub_action->jointree->fromlist);
|
|
|
|
/*
|
|
* There could have been some SubLinks in newjointree, in which
|
|
* case we'd better mark the sub_action correctly.
|
|
*/
|
|
if (parsetree->hasSubLinks && !sub_action->hasSubLinks)
|
|
sub_action->hasSubLinks =
|
|
checkExprHasSubLink((Node *) newjointree);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Event Qualification forces copying of parsetree and splitting into two
|
|
* queries one w/rule_qual, one w/NOT rule_qual. Also add user query qual
|
|
* onto rule action
|
|
*/
|
|
AddQual(sub_action, rule_qual);
|
|
|
|
AddQual(sub_action, parsetree->jointree->quals);
|
|
|
|
/*
|
|
* Rewrite new.attribute w/ right hand side of target-list entry for
|
|
* appropriate field name in insert/update.
|
|
*
|
|
* KLUGE ALERT: since ResolveNew returns a mutated copy, we can't just
|
|
* apply it to sub_action; we have to remember to update the sublink
|
|
* inside rule_action, too.
|
|
*/
|
|
if ((event == CMD_INSERT || event == CMD_UPDATE) &&
|
|
sub_action->commandType != CMD_UTILITY)
|
|
{
|
|
sub_action = (Query *) ResolveNew((Node *) sub_action,
|
|
new_varno,
|
|
0,
|
|
rt_fetch(new_varno,
|
|
sub_action->rtable),
|
|
parsetree->targetList,
|
|
event,
|
|
current_varno,
|
|
NULL);
|
|
if (sub_action_ptr)
|
|
*sub_action_ptr = sub_action;
|
|
else
|
|
rule_action = sub_action;
|
|
}
|
|
|
|
/*
|
|
* If rule_action has a RETURNING clause, then either throw it away if the
|
|
* triggering query has no RETURNING clause, or rewrite it to emit what
|
|
* the triggering query's RETURNING clause asks for. Throw an error if
|
|
* more than one rule has a RETURNING clause.
|
|
*/
|
|
if (!parsetree->returningList)
|
|
rule_action->returningList = NIL;
|
|
else if (rule_action->returningList)
|
|
{
|
|
if (*returning_flag)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("cannot have RETURNING lists in multiple rules")));
|
|
*returning_flag = true;
|
|
rule_action->returningList = (List *)
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* Copy the query's jointree list, and optionally attempt to remove any
|
|
* occurrence of the given rt_index as a top-level join item (we do not look
|
|
* for it within join items; this is OK because we are only expecting to find
|
|
* it as an UPDATE or DELETE target relation, which will be at the top level
|
|
* of the join). Returns modified jointree list --- this is a separate copy
|
|
* sharing no nodes with the original.
|
|
*/
|
|
static List *
|
|
adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
|
|
{
|
|
List *newjointree = copyObject(parsetree->jointree->fromlist);
|
|
ListCell *l;
|
|
|
|
if (removert)
|
|
{
|
|
foreach(l, newjointree)
|
|
{
|
|
RangeTblRef *rtr = lfirst(l);
|
|
|
|
if (IsA(rtr, RangeTblRef) &&
|
|
rtr->rtindex == rt_index)
|
|
{
|
|
newjointree = list_delete_ptr(newjointree, rtr);
|
|
|
|
/*
|
|
* foreach is safe because we exit loop after list_delete...
|
|
*/
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return newjointree;
|
|
}
|
|
|
|
|
|
/*
|
|
* rewriteTargetList - rewrite INSERT/UPDATE targetlist into standard form
|
|
*
|
|
* This has the following responsibilities:
|
|
*
|
|
* 1. For an INSERT, add tlist entries to compute default values for any
|
|
* attributes that have defaults and are not assigned to in the given tlist.
|
|
* (We do not insert anything for default-less attributes, however. The
|
|
* planner will later insert NULLs for them, but there's no reason to slow
|
|
* down rewriter processing with extra tlist nodes.) Also, for both INSERT
|
|
* and UPDATE, replace explicit DEFAULT specifications with column default
|
|
* expressions.
|
|
*
|
|
* 2. Merge multiple entries for the same target attribute, or declare error
|
|
* if we can't. Multiple entries are only allowed for INSERT/UPDATE of
|
|
* portions of an array or record field, for example
|
|
* UPDATE table SET foo[2] = 42, foo[4] = 43;
|
|
* We can merge such operations into a single assignment op. Essentially,
|
|
* the expression we want to produce in this case is like
|
|
* foo = array_set(array_set(foo, 2, 42), 4, 43)
|
|
*
|
|
* 3. Sort the tlist into standard order: non-junk fields in order by resno,
|
|
* then junk fields (these in no particular order).
|
|
*
|
|
* We must do items 1 and 2 before firing rewrite rules, else rewritten
|
|
* references to NEW.foo will produce wrong or incomplete results. Item 3
|
|
* is not needed for rewriting, but will be needed by the planner, and we
|
|
* can do it essentially for free while handling items 1 and 2.
|
|
*
|
|
* 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
|
|
rewriteTargetList(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);
|
|
}
|
|
|
|
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 rewriteTargetList
|
|
* 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;
|
|
}
|
|
|
|
|
|
/*
|
|
* 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];
|
|
|
|
/*
|
|
* 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 ||
|
|
(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,
|
|
bool forUpdatePushedDown)
|
|
{
|
|
Query *rule_action;
|
|
RangeTblEntry *rte,
|
|
*subrte;
|
|
RowMarkClause *rc;
|
|
|
|
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");
|
|
|
|
/*
|
|
* 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 acquire needed locks on
|
|
* the relations it mentions.
|
|
*/
|
|
rule_action = copyObject(linitial(rule->actions));
|
|
|
|
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.
|
|
*/
|
|
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;
|
|
subrte->selectedCols = rte->selectedCols;
|
|
subrte->modifiedCols = rte->modifiedCols;
|
|
|
|
rte->requiredPerms = 0; /* no permission check on subquery itself */
|
|
rte->checkAsUser = InvalidOid;
|
|
rte->selectedCols = NULL;
|
|
rte->modifiedCols = NULL;
|
|
|
|
/*
|
|
* 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 (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/SHARE.
|
|
*
|
|
* This may generate an invalid query, eg if some sub-query uses an
|
|
* aggregate. We leave it to the planner to detect that.
|
|
*
|
|
* NB: this must agree with the parser's transformLockingClause() routine.
|
|
* However, 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
|
|
markQueryForLocking(Query *qry, Node *jtnode,
|
|
bool forUpdate, bool noWait, bool pushedDown)
|
|
{
|
|
if (jtnode == NULL)
|
|
return;
|
|
if (IsA(jtnode, RangeTblRef))
|
|
{
|
|
int rti = ((RangeTblRef *) jtnode)->rtindex;
|
|
RangeTblEntry *rte = rt_fetch(rti, qry->rtable);
|
|
|
|
if (rte->rtekind == RTE_RELATION)
|
|
{
|
|
applyLockingClause(qry, rti, forUpdate, noWait, pushedDown);
|
|
rte->requiredPerms |= ACL_SELECT_FOR_UPDATE;
|
|
}
|
|
else if (rte->rtekind == RTE_SUBQUERY)
|
|
{
|
|
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));
|
|
}
|
|
|
|
|
|
/*
|
|
* 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, false);
|
|
/* 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, bool forUpdatePushedDown)
|
|
{
|
|
int rt_index;
|
|
ListCell *lc;
|
|
|
|
/*
|
|
* 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,
|
|
(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.
|
|
*/
|
|
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,
|
|
forUpdatePushedDown);
|
|
}
|
|
|
|
activeRIRs = list_delete_first(activeRIRs);
|
|
}
|
|
|
|
heap_close(rel, NoLock);
|
|
}
|
|
|
|
/* Recurse into subqueries in WITH */
|
|
foreach(lc, parsetree->cteList)
|
|
{
|
|
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
|
|
|
|
cte->ctequery = (Node *)
|
|
fireRIRrules((Query *) cte->ctequery, activeRIRs, false);
|
|
}
|
|
|
|
/*
|
|
* Recurse into sublink subqueries, too. But we already did the ones in
|
|
* the rtable and cteList.
|
|
*/
|
|
if (parsetree->hasSubLinks)
|
|
query_tree_walker(parsetree, fireRIRonSubLink, (void *) activeRIRs,
|
|
QTW_IGNORE_RC_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,
|
|
rt_fetch(rt_index, parsetree->rtable),
|
|
parsetree->targetList,
|
|
event,
|
|
rt_index,
|
|
&parsetree->hasSubLinks);
|
|
/* And attach the fixed qual */
|
|
AddInvertedQual(parsetree, new_qual);
|
|
|
|
return parsetree;
|
|
}
|
|
|
|
|
|
/*
|
|
* fireRules -
|
|
* Iterate through rule locks applying rules.
|
|
*
|
|
* Input arguments:
|
|
* parsetree - original query
|
|
* rt_index - RT index of result relation in original query
|
|
* event - type of rule event
|
|
* locks - list of rules to fire
|
|
* Output arguments:
|
|
* *instead_flag - set TRUE if any unqualified INSTEAD rule is found
|
|
* (must be initialized to FALSE)
|
|
* *returning_flag - set TRUE if we rewrite RETURNING clause in any rule
|
|
* (must be initialized to FALSE)
|
|
* *qual_product - filled with modified original query if any qualified
|
|
* INSTEAD rule is found (must be initialized to NULL)
|
|
* Return value:
|
|
* list of rule actions adjusted for use with this query
|
|
*
|
|
* Qualified INSTEAD rules generate their action with the qualification
|
|
* condition added. They also generate a modified version of the original
|
|
* query with the negated qualification added, so that it will run only for
|
|
* rows that the qualified action doesn't act on. (If there are multiple
|
|
* qualified INSTEAD rules, we AND all the negated quals onto a single
|
|
* modified original query.) We won't execute the original, unmodified
|
|
* query if we find either qualified or unqualified INSTEAD rules. If
|
|
* we find both, the modified original query is discarded too.
|
|
*/
|
|
static List *
|
|
fireRules(Query *parsetree,
|
|
int rt_index,
|
|
CmdType event,
|
|
List *locks,
|
|
bool *instead_flag,
|
|
bool *returning_flag,
|
|
Query **qual_product)
|
|
{
|
|
List *results = NIL;
|
|
ListCell *l;
|
|
|
|
foreach(l, locks)
|
|
{
|
|
RewriteRule *rule_lock = (RewriteRule *) lfirst(l);
|
|
Node *event_qual = rule_lock->qual;
|
|
List *actions = rule_lock->actions;
|
|
QuerySource qsrc;
|
|
ListCell *r;
|
|
|
|
/* Determine correct QuerySource value for actions */
|
|
if (rule_lock->isInstead)
|
|
{
|
|
if (event_qual != NULL)
|
|
qsrc = QSRC_QUAL_INSTEAD_RULE;
|
|
else
|
|
{
|
|
qsrc = QSRC_INSTEAD_RULE;
|
|
*instead_flag = true; /* report unqualified INSTEAD */
|
|
}
|
|
}
|
|
else
|
|
qsrc = QSRC_NON_INSTEAD_RULE;
|
|
|
|
if (qsrc == QSRC_QUAL_INSTEAD_RULE)
|
|
{
|
|
/*
|
|
* If there are INSTEAD rules with qualifications, the original
|
|
* query is still performed. But all the negated rule
|
|
* qualifications of the INSTEAD rules are added so it does its
|
|
* actions only in cases where the rule quals of all INSTEAD rules
|
|
* are false. Think of it as the default action in a case. We save
|
|
* this in *qual_product so RewriteQuery() can add it to the query
|
|
* list after we mangled it up enough.
|
|
*
|
|
* If we have already found an unqualified INSTEAD rule, then
|
|
* *qual_product won't be used, so don't bother building it.
|
|
*/
|
|
if (!*instead_flag)
|
|
{
|
|
if (*qual_product == NULL)
|
|
*qual_product = copyObject(parsetree);
|
|
*qual_product = CopyAndAddInvertedQual(*qual_product,
|
|
event_qual,
|
|
rt_index,
|
|
event);
|
|
}
|
|
}
|
|
|
|
/* Now process the rule's actions and add them to the result list */
|
|
foreach(r, actions)
|
|
{
|
|
Query *rule_action = lfirst(r);
|
|
|
|
if (rule_action->commandType == CMD_NOTHING)
|
|
continue;
|
|
|
|
rule_action = rewriteRuleAction(parsetree, rule_action,
|
|
event_qual, rt_index, event,
|
|
returning_flag);
|
|
|
|
rule_action->querySource = qsrc;
|
|
rule_action->canSetTag = false; /* might change later */
|
|
|
|
results = lappend(results, rule_action);
|
|
}
|
|
}
|
|
|
|
return results;
|
|
}
|
|
|
|
|
|
/*
|
|
* 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;
|
|
bool returning = 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_UPDATE)
|
|
rewriteTargetList(parsetree, rt_entry_relation, NULL);
|
|
else if (event == CMD_INSERT)
|
|
{
|
|
RangeTblEntry *values_rte = NULL;
|
|
|
|
/*
|
|
* 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 (IsA(rtr, RangeTblRef))
|
|
{
|
|
RangeTblEntry *rte = rt_fetch(rtr->rtindex,
|
|
parsetree->rtable);
|
|
|
|
if (rte->rtekind == RTE_VALUES)
|
|
values_rte = rte;
|
|
}
|
|
}
|
|
|
|
if (values_rte)
|
|
{
|
|
List *attrnos;
|
|
|
|
/* Process the main targetlist ... */
|
|
rewriteTargetList(parsetree, rt_entry_relation, &attrnos);
|
|
/* ... and the VALUES expression lists */
|
|
rewriteValuesRTE(values_rte, rt_entry_relation, attrnos);
|
|
}
|
|
else
|
|
{
|
|
/* Process just the main targetlist */
|
|
rewriteTargetList(parsetree, rt_entry_relation, NULL);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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,
|
|
&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;
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
}
|
|
|
|
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, false);
|
|
|
|
/*
|
|
* 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;
|
|
}
|