greenplumn rewriteHandler 源码
greenplumn rewriteHandler 代码
文件路径：/src/backend/rewrite/rewriteHandler.c
/*-------------------------------------------------------------------------
*
* rewriteHandler.c
* Primary module of query rewriter.
*
* Portions Copyright (c) 2006-2008, Greenplum inc
* Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/rewrite/rewriteHandler.c
*
* NOTES
* Some of the terms used in this file are of historic nature: "retrieve"
* was the PostQUEL keyword for what today is SELECT. "RIR" stands for
* "Retrieve-Instead-Retrieve", that is an ON SELECT DO INSTEAD SELECT rule
* (which has to be unconditional and where only one rule can exist on each
* relation).
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/relation.h"
#include "access/sysattr.h"
#include "access/table.h"
#include "catalog/dependency.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "foreign/fdwapi.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/analyze.h"
#include "parser/parse_coerce.h"
#include "parser/parse_relation.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteManip.h"
#include "rewrite/rowsecurity.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.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;
typedef struct acquireLocksOnSubLinks_context
{
bool for_execute; /* AcquireRewriteLocks' forExecute param */
} acquireLocksOnSubLinks_context;
static bool acquireLocksOnSubLinks(Node *node,
acquireLocksOnSubLinks_context *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 List *rewriteTargetListIU(List *targetList,
CmdType commandType,
OverridingKind override,
Relation target_relation,
int result_rti);
static TargetEntry *process_matched_tle(TargetEntry *src_tle,
TargetEntry *prior_tle,
const char *attrName);
static Node *get_assignment_input(Node *node);
static bool rewriteValuesRTE(Query *parsetree, RangeTblEntry *rte, int rti,
Relation target_relation, bool force_nulls);
static void markQueryForLocking(Query *qry, Node *jtnode,
LockClauseStrength strength, LockWaitPolicy waitPolicy,
bool pushedDown);
static List *matchLocks(CmdType event, RuleLock *rulelocks,
int varno, Query *parsetree, bool *hasUpdate);
static Query *fireRIRrules(Query *parsetree, List *activeRIRs);
static bool view_has_instead_trigger(Relation view, CmdType event);
static Bitmapset *adjust_view_column_set(Bitmapset *cols, List *targetlist);
/*
* 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, planning, and executing the query.
*
* Caution: this may modify the querytree, therefore caller should usually
* have done a copyObject() to make a writable copy of the querytree in the
* current memory context.
*
* forExecute indicates that the query is about to be executed. If so,
* we'll acquire the lock modes specified in the RTE rellockmode fields.
* If forExecute is false, AccessShareLock is acquired on all relations.
* This case is suitable for ruleutils.c, for example, where we only need
* schema stability and we don't intend to actually modify any relations.
*
* forUpdatePushedDown indicates that a pushed-down FOR [KEY] UPDATE/SHARE
* applies to the current subquery, requiring all rels to be opened with at
* least RowShareLock. This should always be false at the top of the
* recursion. When it is true, we adjust RTE rellockmode fields to reflect
* the higher lock level. This flag is ignored if forExecute is false.
*
* A secondary purpose of this routine is to fix up JOIN RTE references to
* dropped columns (see details below). Such RTEs are modified in-place.
*
* 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 pointers.
*
* (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 forExecute,
bool forUpdatePushedDown)
{
ListCell *l;
int rt_index;
acquireLocksOnSubLinks_context context;
context.for_execute = forExecute;
/*
* First, process RTEs of the current query level.
*/
rt_index = 0;
foreach(l, parsetree->rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
Relation rel;
LOCKMODE lockmode;
bool needLockUpgrade;
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, planner, and executor against schema changes
* mid-query.
*
* If forExecute is false, ignore rellockmode and just use
* AccessShareLock.
*
* CDB: The proper lock mode depends on whether the relation is
* local or distributed, which is discovered by heap_open().
* To handle this we make use of CdbOpenRelation().
*
* For update should hold ExclusiveLock, see the discussion on
* https://groups.google.com/a/greenplum.org/d/msg/gpdb-dev/p-6_dNjnRMQ/OzTnb586AwAJ
*
* Update|DELETE may have to upgrade the locks to avoid global
* deadlock and CdbOpenRelation will do more check for AO table
* and GDD's status.
*/
needLockUpgrade = false;
if (!forExecute)
lockmode = AccessShareLock;
else if (rt_index == parsetree->resultRelation)
{
lockmode = RowExclusiveLock;
needLockUpgrade = (parsetree->commandType == CMD_UPDATE ||
parsetree->commandType == CMD_DELETE);
}
else if (forUpdatePushedDown ||
get_parse_rowmark(parsetree, rt_index) != NULL)
{
/*
* Greenplum specific behavior:
* The implementation of select statement with locking clause
* (for update | no key update | share | key share) in postgres
* is to hold RowShareLock on tables during parsing stage, and
* generate a LockRows plan node for executor to lock the tuples.
* It is not easy to lock tuples in Greenplum database, since
* tuples may be fetched through motion nodes.
*
* But when Global Deadlock Detector is enabled, and the select
* statement with locking clause contains only one table, we are
* sure that there are no motions. For such simple cases, we could
* make the behavior just the same as Postgres.
*/
if (!parsetree->canOptSelectLockingClause)
rte->rellockmode = ExclusiveLock;
/* Upgrade RTE's lock mode to reflect pushed-down lock */
if (rte->rellockmode == AccessShareLock)
rte->rellockmode = RowShareLock;
lockmode = rte->rellockmode;
}
else
lockmode = rte->rellockmode;
/* Take a lock either using CDB lock promotion or not */
if (needLockUpgrade)
{
rel = CdbOpenTable(rte->relid, lockmode, NULL);
}
else
{
rel = table_open(rte->relid, lockmode);
}
/*
* While we have the relation open, update the RTE's relkind,
* just in case it changed since this rule was made.
*/
rte->relkind = rel->rd_rel->relkind;
/* Close the relcache entry without releasing the lock. */
table_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
* pointers.
*
* 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 *aliasitem = (Var *) lfirst(ll);
Var *aliasvar = aliasitem;
/* Look through any implicit coercion */
aliasvar = (Var *) strip_implicit_coercions((Node *) aliasvar);
/*
* 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
* pointer already? But that's OK too.)
*/
if (aliasvar && 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))
{
/* Replace the join alias item with a NULL */
aliasitem = NULL;
}
}
newaliasvars = lappend(newaliasvars, aliasitem);
}
rte->joinaliasvars = newaliasvars;
break;
case RTE_SUBQUERY:
case RTE_TABLEFUNCTION:
/*
* The subquery RTE itself is all right, but we have to
* recurse to process the represented subquery.
*/
AcquireRewriteLocks(rte->subquery,
forExecute,
(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, forExecute, 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, &context,
QTW_IGNORE_RC_SUBQUERIES);
}
/*
* Walker to find sublink subqueries for AcquireRewriteLocks
*/
static bool
acquireLocksOnSubLinks(Node *node, acquireLocksOnSubLinks_context *context)
{
if (node == NULL)
return false;
if (IsA(node, SubLink))
{
SubLink *sub = (SubLink *) node;
/* Do what we came for */
AcquireRewriteLocks((Query *) sub->subselect,
context->for_execute,
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;
acquireLocksOnSubLinks_context context;
context.for_execute = true;
/*
* 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 = copyObject(rule_action);
rule_qual = copyObject(rule_qual);
/*
* Acquire necessary locks and fix any deleted JOIN RTE entries.
*/
AcquireRewriteLocks(rule_action, true, false);
(void) acquireLocksOnSubLinks(rule_qual, &context);
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(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_RELATION:
sub_action->hasSubLinks =
checkExprHasSubLink((Node *) rte->tablesample);
break;
case RTE_TABLEFUNCTION:
sub_action->hasSubLinks =
checkExprHasSubLink((Node *) rte->functions);
break;
case RTE_FUNCTION:
sub_action->hasSubLinks =
checkExprHasSubLink((Node *) rte->functions);
break;
case RTE_TABLEFUNC:
sub_action->hasSubLinks =
checkExprHasSubLink((Node *) rte->tablefunc);
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 */
}
}
/*
* Also, we might have absorbed some RTEs with RLS conditions into the
* sub_action. If so, mark it as hasRowSecurity, whether or not those
* RTEs will be referenced after we finish rewriting. (Note: currently
* this is a no-op because RLS conditions aren't added till later, but it
* seems like good future-proofing to do this anyway.)
*/
sub_action->hasRowSecurity |= parsetree->hasRowSecurity;
/*
* 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);
}
}
/*
* If the original query has any CTEs, copy them into the rule action. But
* we don't need them for a utility action.
*/
if (parsetree->cteList != NIL && sub_action->commandType != CMD_UTILITY)
{
ListCell *lc;
/*
* Annoying implementation restriction: because CTEs are identified by
* name within a cteList, we can't merge a CTE from the original query
* if it has the same name as any CTE in the rule action.
*
* This could possibly be fixed by using some sort of internally
* generated ID, instead of names, to link CTE RTEs to their CTEs.
*/
foreach(lc, parsetree->cteList)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
ListCell *lc2;
foreach(lc2, sub_action->cteList)
{
CommonTableExpr *cte2 = (CommonTableExpr *) lfirst(lc2);
if (strcmp(cte->ctename, cte2->ctename) == 0)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("WITH query name \"%s\" appears in both a rule action and the query being rewritten",
cte->ctename)));
}
}
/* OK, it's safe to combine the CTE lists */
sub_action->cteList = list_concat(sub_action->cteList,
copyObject(parsetree->cteList));
}
/*
* 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 with right hand side of target-list entry for
* appropriate field name in insert/update.
*
* KLUGE ALERT: since ReplaceVarsFromTargetList 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 *)
ReplaceVarsFromTargetList((Node *) sub_action,
new_varno,
0,
rt_fetch(new_varno, sub_action->rtable),
parsetree->targetList,
(event == CMD_UPDATE) ?
REPLACEVARS_CHANGE_VARNO :
REPLACEVARS_SUBSTITUTE_NULL,
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 *)
ReplaceVarsFromTargetList((Node *) parsetree->returningList,
parsetree->resultRelation,
0,
rt_fetch(parsetree->resultRelation,
parsetree->rtable),
rule_action->returningList,
REPLACEVARS_REPORT_ERROR,
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;
}
/*
* 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 trigger-updatable 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.) This is only necessary for
* trigger-updatable views, for which the view remains the result relation of
* the query. For auto-updatable views we must not do this, since it might
* add assignments to non-updatable view columns. For rule-updatable views it
* is unnecessary extra work, since the query will be rewritten with a
* different result relation which will be processed when we recurse via
* RewriteQuery.
*
* 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_element(array_set_element(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.
*
* Note that for an inheritable UPDATE, this processing is only done once,
* using the parent relation as reference. It must not do anything that
* will not be correct when transposed to the child relation(s). (Step 4
* is incorrect by this light, since child relations might have different
* column ordering, but the planner will fix things by re-sorting the tlist
* for each child.)
*/
static List *
rewriteTargetListIU(List *targetList,
CmdType commandType,
OverridingKind override,
Relation target_relation,
int result_rti)
{
TargetEntry **new_tles;
List *new_tlist = NIL;
List *junk_tlist = NIL;
Form_pg_attribute att_tup;
int attrno,
next_junk_attrno,
numattrs;
ListCell *temp;
/*
* We process the normal (non-junk) attributes by scanning the input tlist
* once and transferring TLEs into an array, then scanning the array to
* build an output tlist. This avoids O(N^2) behavior for large numbers
* of attributes.
*
* Junk attributes are tossed into a separate list during the same tlist
* scan, then appended to the reconstructed tlist.
*/
numattrs = RelationGetNumberOfAttributes(target_relation);
new_tles = (TargetEntry **) palloc0(numattrs * sizeof(TargetEntry *));
next_junk_attrno = numattrs + 1;
foreach(temp, 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 = TupleDescAttr(target_relation->rd_att, attrno - 1);
/* We can (and must) ignore deleted attributes */
if (att_tup->attisdropped)
continue;
/* Merge with any prior assignment to same attribute */
new_tles[attrno - 1] =
process_matched_tle(old_tle,
new_tles[attrno - 1],
NameStr(att_tup->attname));
}
else
{
/*
* Copy all resjunk tlist entries to junk_tlist, and assign them
* resnos above the last real resno.
*
* Typical junk entries include ORDER BY or GROUP BY expressions
* (are these actually possible in an INSERT or UPDATE?), system
* attribute references, etc.
*/
/* Get the resno right, but don't copy unnecessarily */
if (old_tle->resno != next_junk_attrno)
{
old_tle = flatCopyTargetEntry(old_tle);
old_tle->resno = next_junk_attrno;
}
junk_tlist = lappend(junk_tlist, old_tle);
next_junk_attrno++;
}
}
for (attrno = 1; attrno <= numattrs; attrno++)
{
TargetEntry *new_tle = new_tles[attrno - 1];
bool apply_default;
att_tup = TupleDescAttr(target_relation->rd_att, 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.
*/
apply_default = ((new_tle == NULL && commandType == CMD_INSERT) ||
(new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)));
if (commandType == CMD_INSERT)
{
if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && !apply_default)
{
if (override != OVERRIDING_SYSTEM_VALUE)
ereport(ERROR,
(errcode(ERRCODE_GENERATED_ALWAYS),
errmsg("cannot insert into column \"%s\"", NameStr(att_tup->attname)),
errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
NameStr(att_tup->attname)),
errhint("Use OVERRIDING SYSTEM VALUE to override.")));
}
if (att_tup->attidentity == ATTRIBUTE_IDENTITY_BY_DEFAULT && override == OVERRIDING_USER_VALUE)
apply_default = true;
if (att_tup->attgenerated && !apply_default)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("cannot insert into column \"%s\"", NameStr(att_tup->attname)),
errdetail("Column \"%s\" is a generated column.",
NameStr(att_tup->attname))));
}
if (commandType == CMD_UPDATE)
{
if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && new_tle && !apply_default)
ereport(ERROR,
(errcode(ERRCODE_GENERATED_ALWAYS),
errmsg("column \"%s\" can only be updated to DEFAULT", NameStr(att_tup->attname)),
errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
NameStr(att_tup->attname))));
if (att_tup->attgenerated && new_tle && !apply_default)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("column \"%s\" can only be updated to DEFAULT", NameStr(att_tup->attname)),
errdetail("Column \"%s\" is a generated column.",
NameStr(att_tup->attname))));
}
if (att_tup->attgenerated)
{
/*
* stored generated column will be fixed in executor
*/
new_tle = NULL;
}
else if (apply_default)
{
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->attcollation,
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,
COERCION_IMPLICIT,
COERCE_IMPLICIT_CAST,
-1,
false);
}
}
if (new_expr)
new_tle = makeTargetEntry((Expr *) new_expr,
attrno,
pstrdup(NameStr(att_tup->attname)),
false);
}
/*
* For an UPDATE on a trigger-updatable 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 &&
view_has_instead_trigger(target_relation, CMD_UPDATE))
{
Node *new_expr;
new_expr = (Node *) makeVar(result_rti,
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);
return 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;
CoerceToDomain *coerce_expr = NULL;
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 SubscriptingRef 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, y))
* However, we can ignore the substructure and just consider the top
* FieldStore or SubscriptingRef from each assignment, because it works to
* combine these as
* FieldStore(FieldStore(col, fld1,
* FieldStore(placeholder, subfld1, x)),
* fld2, FieldStore(placeholder, subfld2, y))
* 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
* SubscriptingRefs are involved though.
*
* As a further complication, the destination column might be a domain,
* resulting in each assignment containing a CoerceToDomain node over a
* FieldStore or SubscriptingRef. These should have matching target
* domains, so we strip them and reconstitute a single CoerceToDomain over
* the combined FieldStore/SubscriptingRef nodes. (Notice that this has the
* result that the domain's checks are applied only after we do all the
* field or element updates, not after each one. This is arguably desirable.)
*----------
*/
src_expr = (Node *) src_tle->expr;
prior_expr = (Node *) prior_tle->expr;
if (src_expr && IsA(src_expr, CoerceToDomain) &&
prior_expr && IsA(prior_expr, CoerceToDomain) &&
((CoerceToDomain *) src_expr)->resulttype ==
((CoerceToDomain *) prior_expr)->resulttype)
{
/* we assume without checking that resulttypmod/resultcollid match */
coerce_expr = (CoerceToDomain *) src_expr;
src_expr = (Node *) ((CoerceToDomain *) src_expr)->arg;
prior_expr = (Node *) ((CoerceToDomain *) prior_expr)->arg;
}
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, SubscriptingRef))
{
SubscriptingRef *sbsref = makeNode(SubscriptingRef);
memcpy(sbsref, src_expr, sizeof(SubscriptingRef));
sbsref->refexpr = (Expr *) prior_expr;
newexpr = (Node *) sbsref;
}
else
{
elog(ERROR, "cannot happen");
newexpr = NULL;
}
if (coerce_expr)
{
/* put back the CoerceToDomain */
CoerceToDomain *newcoerce = makeNode(CoerceToDomain);
memcpy(newcoerce, coerce_expr, sizeof(CoerceToDomain));
newcoerce->arg = (Expr *) newexpr;
newexpr = (Node *) newcoerce;
}
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, SubscriptingRef))
{
SubscriptingRef *sbsref = (SubscriptingRef *) node;
if (sbsref->refassgnexpr == NULL)
return NULL;
return (Node *) sbsref->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 = TupleDescAttr(rd_att, attrno - 1);
Oid atttype = att_tup->atttypid;
int32 atttypmod = att_tup->atttypmod;
Node *expr = NULL;
Oid exprtype;
if (att_tup->attidentity)
{
NextValueExpr *nve = makeNode(NextValueExpr);
nve->seqid = getOwnedSequence(RelationGetRelid(rel), attrno);
nve->typeId = att_tup->atttypid;
return (Node *) nve;
}
/*
* Scan to see if relation has a default for this column.
*/
if (att_tup->atthasdef && 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;
}
}
}
/*
* No per-column default, so look for a default for the type itself. But
* not for generated columns.
*/
if (expr == NULL && !att_tup->attgenerated)
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.
*
* For an auto-updatable view, each DEFAULT item in the VALUES list is
* replaced with the default from the view, if it has one. Otherwise it is
* left untouched so that the underlying base relation's default can be
* applied instead (when we later recurse to here after rewriting the query
* to refer to the base relation instead of the view).
*
* For other types of relation, including rule- and trigger-updatable views,
* all DEFAULT items are replaced, and if the target relation doesn't have a
* default, the value is explicitly set to NULL.
*
* Additionally, if force_nulls is true, the target relation's defaults are
* ignored and all DEFAULT items in the VALUES list are explicitly set to
* NULL, regardless of the target relation's type. This is used for the
* product queries generated by DO ALSO rules attached to an auto-updatable
* view, for which we will have already called this function with force_nulls
* false. For these product queries, we must then force any remaining DEFAULT
* items to NULL to provide concrete values for the rule actions.
* Essentially, this is a mix of the 2 cases above --- the original query is
* an insert into an auto-updatable view, and the product queries are inserts
* into a rule-updatable view.
*
* Note that we may have subscripted or field assignment targetlist entries,
* as well as more complex expressions from already-replaced DEFAULT items if
* we have recursed to here for an auto-updatable view. However, it ought to
* be impossible for such entries to have DEFAULTs assigned to them --- we
* should only have to replace DEFAULT items for targetlist entries that
* contain simple Vars referencing the VALUES RTE.
*
* Returns true if all DEFAULT items were replaced, and false if some were
* left untouched.
*/
static bool
rewriteValuesRTE(Query *parsetree, RangeTblEntry *rte, int rti,
Relation target_relation, bool force_nulls)
{
List *newValues;
ListCell *lc;
bool isAutoUpdatableView;
bool allReplaced;
int numattrs;
int *attrnos;
/*
* 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.
*
* We skip this check if force_nulls is true, because we know that there
* are DEFAULT items present in that case.
*/
if (!force_nulls && !searchForDefault(rte))
return true; /* nothing to do */
/*
* Scan the targetlist for entries referring to the VALUES RTE, and note
* the target attributes. As noted above, we should only need to do this
* for targetlist entries containing simple Vars --- nothing else in the
* VALUES RTE should contain DEFAULT items, and we complain if such a
* thing does occur.
*/
numattrs = list_length(linitial(rte->values_lists));
attrnos = (int *) palloc0(numattrs * sizeof(int));
foreach(lc, parsetree->targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
if (IsA(tle->expr, Var))
{
Var *var = (Var *) tle->expr;
if (var->varno == rti)
{
int attrno = var->varattno;
Assert(attrno >= 1 && attrno <= numattrs);
attrnos[attrno - 1] = tle->resno;
}
}
}
/*
* Check if the target relation is an auto-updatable view, in which case
* unresolved defaults will be left untouched rather than being set to
* NULL. If force_nulls is true, we always set DEFAULT items to NULL, so
* skip this check in that case --- it isn't an auto-updatable view.
*/
isAutoUpdatableView = false;
if (!force_nulls &&
target_relation->rd_rel->relkind == RELKIND_VIEW &&
!view_has_instead_trigger(target_relation, CMD_INSERT))
{
List *locks;
bool hasUpdate;
bool found;
ListCell *l;
/* Look for an unconditional DO INSTEAD rule */
locks = matchLocks(CMD_INSERT, target_relation->rd_rules,
parsetree->resultRelation, parsetree, &hasUpdate);
found = false;
foreach(l, locks)
{
RewriteRule *rule_lock = (RewriteRule *) lfirst(l);
if (rule_lock->isInstead &&
rule_lock->qual == NULL)
{
found = true;
break;
}
}
/*
* If we didn't find an unconditional DO INSTEAD rule, assume that the
* view is auto-updatable. If it isn't, rewriteTargetView() will
* throw an error.
*/
if (!found)
isAutoUpdatableView = true;
}
newValues = NIL;
allReplaced = true;
foreach(lc, rte->values_lists)
{
List *sublist = (List *) lfirst(lc);
List *newList = NIL;
ListCell *lc2;
int i;
Assert(list_length(sublist) == numattrs);
i = 0;
foreach(lc2, sublist)
{
Node *col = (Node *) lfirst(lc2);
int attrno = attrnos[i++];
if (IsA(col, SetToDefault))
{
Form_pg_attribute att_tup;
Node *new_expr;
if (attrno == 0)
elog(ERROR, "cannot set value in column %d to DEFAULT", i);
att_tup = TupleDescAttr(target_relation->rd_att, attrno - 1);
if (!force_nulls && !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, unless the
* target relation is an auto-updatable view.
*/
if (!new_expr)
{
if (isAutoUpdatableView)
{
/* Leave the value untouched */
newList = lappend(newList, col);
allReplaced = false;
continue;
}
new_expr = (Node *) makeConst(att_tup->atttypid,
-1,
att_tup->attcollation,
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,
COERCION_IMPLICIT,
COERCE_IMPLICIT_CAST,
-1,
false);
}
newList = lappend(newList, new_expr);
}
else
newList = lappend(newList, col);
}
newValues = lappend(newValues, newList);
}
rte->values_lists = newValues;
pfree(attrnos);
return allReplaced;
}
/*
* 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 foreign table, we let the FDW decide
* what to add.
*
* We used to do this during RewriteQuery(), but now that inheritance trees
* can contain a mix of regular and foreign tables, we must postpone it till
* planning, after the inheritance tree has been expanded. In that way we
* can do the right thing for each child table.
*/
void
rewriteTargetListUD(Query *parsetree, RangeTblEntry *target_rte,
Relation target_relation)
{
Var *var = NULL;
const char *attrname;
TargetEntry *tle;
Var *varSegid = NULL;
if (target_relation->rd_rel->relkind == RELKIND_RELATION ||
target_relation->rd_rel->relkind == RELKIND_MATVIEW ||
target_relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
{
/*
* Emit CTID so that executor can find the row to update or delete.
*/
var = makeVar(parsetree->resultRelation,
SelfItemPointerAttributeNumber,
TIDOID,
-1,
InvalidOid,
0);
attrname = "ctid";
/*
* GPDB also needs gp_segment_id. ctid is only unique in the same
* segment.
*/
{
Oid reloid;
Oid vartypeid;
int32 type_mod;
Oid type_coll;
reloid = RelationGetRelid(target_relation);
get_atttypetypmodcoll(reloid, GpSegmentIdAttributeNumber, &vartypeid, &type_mod, &type_coll);
varSegid = makeVar(parsetree->resultRelation,
GpSegmentIdAttributeNumber,
vartypeid,
type_mod,
type_coll,
0);
}
}
else if (target_relation->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
{
/*
* Let the foreign table's FDW add whatever junk TLEs it wants.
*/
FdwRoutine *fdwroutine;
fdwroutine = GetFdwRoutineForRelation(target_relation, false);
if (fdwroutine->AddForeignUpdateTargets != NULL)
fdwroutine->AddForeignUpdateTargets(parsetree, target_rte,
target_relation);
/*
* If we have a row-level trigger corresponding to the operation, emit
* a whole-row Var so that executor will have the "old" row to pass to
* the trigger. Alas, this misses system columns.
*/
if (target_relation->trigdesc &&
((parsetree->commandType == CMD_UPDATE &&
(target_relation->trigdesc->trig_update_after_row ||
target_relation->trigdesc->trig_update_before_row)) ||
(parsetree->commandType == CMD_DELETE &&
(target_relation->trigdesc->trig_delete_after_row ||
target_relation->trigdesc->trig_delete_before_row))))
{
var = makeWholeRowVar(target_rte,
parsetree->resultRelation,
0,
false);
attrname = "wholerow";
/*
* GPDB also needs gp_segment_id. ctid is only unique in the same
* segment.
*/
{
Oid reloid;
Oid vartypeid;
int32 type_mod;
Oid type_coll;
reloid = RelationGetRelid(target_relation);
get_atttypetypmodcoll(reloid, GpSegmentIdAttributeNumber, &vartypeid, &type_mod, &type_coll);
varSegid = makeVar(parsetree->resultRelation,
GpSegmentIdAttributeNumber,
vartypeid,
type_mod,
type_coll,
0);
}
}
}
if (var != NULL)
{
tle = makeTargetEntry((Expr *) var,
list_length(parsetree->targetList) + 1,
pstrdup(attrname),
true);
parsetree->targetList = lappend(parsetree->targetList, tle);
}
if (varSegid)
{
tle = makeTargetEntry((Expr *) varSegid,
list_length(parsetree->targetList) + 1, /* resno */
pstrdup("gp_segment_id"), /* resname */
true); /* resjunk */
parsetree->targetList = lappend(parsetree->targetList, tle);
}
}
/*
* matchLocks -
* match the list of locks and returns the matching rules
*/
static List *
matchLocks(CmdType event,
RuleLock *rulelocks,
int varno,
Query *parsetree,
bool *hasUpdate)
{
List *matching_locks = NIL;
int nlocks;
int i;
if (rulelocks == NULL)
return NIL;
if (parsetree->commandType != CMD_SELECT)
{
if (parsetree->resultRelation != varno)
return NIL;
}
nlocks = rulelocks->numLocks;
for (i = 0; i < nlocks; i++)
{
RewriteRule *oneLock = rulelocks->rules[i];
if (oneLock->event == CMD_UPDATE)
*hasUpdate = true;
/*
* 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))
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,
Relation relation,
List *activeRIRs)
{
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 (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;
Var *var;
TargetEntry *tle;
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->insertedCols = NULL;
rte->updatedCols = 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);
/*
* To allow the executor to compute the original view row to pass
* to the INSTEAD OF trigger, we add a resjunk whole-row Var
* referencing the original RTE. This will later get expanded
* into a RowExpr computing all the OLD values of the view row.
*/
var = makeWholeRowVar(rte, rt_index, 0, false);
tle = makeTargetEntry((Expr *) var,
list_length(parsetree->targetList) + 1,
pstrdup("wholerow"),
true);
parsetree->targetList = lappend(parsetree->targetList, tle);
/* Now, continue with expanding the original view RTE */
}
else
elog(ERROR, "unrecognized commandType: %d",
(int) parsetree->commandType);
}
/*
* Check if there's a FOR [KEY] UPDATE/SHARE clause applying to this view.
*
* Note: we needn't explicitly consider any such clauses appearing in
* ancestor query levels; their effects have already been pushed down to
* here by markQueryForLocking, and will be reflected in "rc".
*/
rc = get_parse_rowmark(parsetree, rt_index);
/*
* Make a modifiable copy of the view query, and acquire needed locks on
* the relations it mentions. Force at least RowShareLock for all such
* rels if there's a FOR [KEY] UPDATE/SHARE clause affecting this view.
*/
rule_action = copyObject(linitial(rule->actions));
AcquireRewriteLocks(rule_action, true, (rc != NULL));
/*
* If FOR [KEY] UPDATE/SHARE of view, mark all the contained tables as
* implicit FOR [KEY] UPDATE/SHARE, the same as the parser would have done
* if the view's subquery had been written out explicitly.
*/
if (rc != NULL)
markQueryForLocking(rule_action, (Node *) rule_action->jointree,
rc->strength, rc->waitPolicy, true);
/*
* Recursively expand any view references inside the view.
*
* Note: this must happen after markQueryForLocking. That way, any UPDATE
* permission bits needed for sub-views are initially applied to their
* RTE_RELATION RTEs by markQueryForLocking, and then transferred to their
* OLD rangetable entries by the action below (in a recursive call of this
* routine).
*/
rule_action = fireRIRrules(rule_action, activeRIRs);
/*
* Now, plug the view query in as a subselect, converting the relation's
* original RTE to a subquery RTE.
*/
rte = rt_fetch(rt_index, parsetree->rtable);
rte->rtekind = RTE_SUBQUERY;
rte->subquery = rule_action;
rte->security_barrier = RelationIsSecurityView(relation);
/* Clear fields that should not be set in a subquery RTE */
rte->relid = InvalidOid;
rte->relkind = 0;
rte->rellockmode = 0;
rte->tablesample = NULL;
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->insertedCols = rte->insertedCols;
subrte->updatedCols = rte->updatedCols;
subrte->extraUpdatedCols = rte->extraUpdatedCols;
rte->requiredPerms = 0; /* no permission check on subquery itself */
rte->checkAsUser = InvalidOid;
rte->selectedCols = NULL;
rte->insertedCols = NULL;
rte->updatedCols = NULL;
rte->extraUpdatedCols = NULL;
return parsetree;
}
/*
* Recursively mark all relations used by a view as FOR [KEY] 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,
LockClauseStrength strength, LockWaitPolicy waitPolicy,
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, strength, waitPolicy, pushedDown);
rte->requiredPerms |= ACL_SELECT_FOR_UPDATE;
}
else if (rte->rtekind == RTE_SUBQUERY)
{
applyLockingClause(qry, rti, strength, waitPolicy, pushedDown);
/* FOR UPDATE/SHARE of subquery is propagated to subquery's rels */
markQueryForLocking(rte->subquery, (Node *) rte->subquery->jointree,
strength, waitPolicy, 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), strength, waitPolicy, pushedDown);
}
else if (IsA(jtnode, JoinExpr))
{
JoinExpr *j = (JoinExpr *) jtnode;
markQueryForLocking(qry, j->larg, strength, waitPolicy, pushedDown);
markQueryForLocking(qry, j->rarg, strength, waitPolicy, 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);
/* 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 the given query
*
* activeRIRs is a list of the OIDs of views we're already processing RIR
* rules for, used to detect/reject recursion.
*/
static Query *
fireRIRrules(Query *parsetree, List *activeRIRs)
{
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...
*/
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->rtekind == RTE_TABLEFUNCTION)
{
rte->subquery = fireRIRrules(rte->subquery, activeRIRs);
continue;
}
/*
* Joins and other non-relation RTEs can be ignored completely.
*/
if (rte->rtekind != RTE_RELATION)
continue;
/*
* Always ignore RIR rules for materialized views referenced in
* queries. (This does not prevent refreshing MVs, since they aren't
* referenced in their own query definitions.)
*
* Note: in the future we might want to allow MVs to be conditionally
* expanded as if they were regular views, if they are not scannable.
* In that case this test would need to be postponed till after we've
* opened the rel, so that we could check its state.
*/
if (rte->relkind == RELKIND_MATVIEW)
continue;
/*
* In INSERT ... ON CONFLICT, ignore the EXCLUDED pseudo-relation;
* even if it points to a view, we needn't expand it, and should not
* because we want the RTE to remain of RTE_RELATION type. Otherwise,
* it would get changed to RTE_SUBQUERY type, which is an
* untested/unsupported situation.
*/
if (parsetree->onConflict &&
rt_index == parsetree->onConflict->exclRelIndex)
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;
/*
* 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 &&
rt_index != origResultRelation)
continue;
/*
* We can use NoLock here since either the parser or
* AcquireRewriteLocks should have locked the rel already.
*/
rel = table_open(rte->relid, NoLock);
/*
* Collect the RIR rules that we must apply
*/
rules = rel->rd_rules;
if (rules != NULL)
{
locks = NIL;
for (i = 0; i < rules->numLocks; i++)
{
rule = rules->rules[i];
if (rule->event != CMD_SELECT)
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,
rel,
activeRIRs);
}
activeRIRs = list_delete_first(activeRIRs);
}
}
table_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);
}
/*
* 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);
/*
* Apply any row level security policies. We do this last because it
* requires special recursion detection if the new quals have sublink
* subqueries, and if we did it in the loop above query_tree_walker would
* then recurse into those quals a second time.
*/
rt_index = 0;
foreach(lc, parsetree->rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
Relation rel;
List *securityQuals;
List *withCheckOptions;
bool hasRowSecurity;
bool hasSubLinks;
++rt_index;
/* Only normal relations can have RLS policies */
if (rte->rtekind != RTE_RELATION ||
(rte->relkind != RELKIND_RELATION &&
rte->relkind != RELKIND_PARTITIONED_TABLE))
continue;
rel = table_open(rte->relid, NoLock);
/*
* Fetch any new security quals that must be applied to this RTE.
*/
get_row_security_policies(parsetree, rte, rt_index,
&securityQuals, &withCheckOptions,
&hasRowSecurity, &hasSubLinks);
if (securityQuals != NIL || withCheckOptions != NIL)
{
if (hasSubLinks)
{
acquireLocksOnSubLinks_context context;
/*
* Recursively process the new quals, checking for infinite
* recursion.
*/
if (list_member_oid(activeRIRs, RelationGetRelid(rel)))
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("infinite recursion detected in policy for relation \"%s\"",
RelationGetRelationName(rel))));
activeRIRs = lcons_oid(RelationGetRelid(rel), activeRIRs);
/*
* get_row_security_policies just passed back securityQuals
* and/or withCheckOptions, and there were SubLinks, make sure
* we lock any relations which are referenced.
*
* These locks would normally be acquired by the parser, but
* securityQuals and withCheckOptions are added post-parsing.
*/
context.for_execute = true;
(void) acquireLocksOnSubLinks((Node *) securityQuals, &context);
(void) acquireLocksOnSubLinks((Node *) withCheckOptions,
&context);
/*
* Now that we have the locks on anything added by
* get_row_security_policies, fire any RIR rules for them.
*/
expression_tree_walker((Node *) securityQuals,
fireRIRonSubLink, (void *) activeRIRs);
expression_tree_walker((Node *) withCheckOptions,
fireRIRonSubLink, (void *) activeRIRs);
activeRIRs = list_delete_first(activeRIRs);
}
/*
* Add the new security barrier quals to the start of the RTE's
* list so that they get applied before any existing barrier quals
* (which would have come from a security-barrier view, and should
* get lower priority than RLS conditions on the table itself).
*/
rte->securityQuals = list_concat(securityQuals,
rte->securityQuals);
parsetree->withCheckOptions = list_concat(withCheckOptions,
parsetree->withCheckOptions);
}
/*
* Make sure the query is marked correctly if row level security
* applies, or if the new quals had sublinks.
*/
if (hasRowSecurity)
parsetree->hasRowSecurity = true;
if (hasSubLinks)
parsetree->hasSubLinks = true;
table_close(rel, NoLock);
}
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 = copyObject(rule_qual);
acquireLocksOnSubLinks_context context;
context.for_execute = true;
/*
* 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, &context);
/* 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 = ReplaceVarsFromTargetList(new_qual,
PRS2_NEW_VARNO,
0,
rt_fetch(rt_index,
parsetree->rtable),
parsetree->targetList,
(event == CMD_UPDATE) ?
REPLACEVARS_CHANGE_VARNO :
REPLACEVARS_SUBSTITUTE_NULL,
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;
}
/*
* get_view_query - get the Query from a view's _RETURN rule.
*
* Caller should have verified that the relation is a view, and therefore
* we should find an ON SELECT action.
*
* Note that the pointer returned is into the relcache and therefore must
* be treated as read-only to the caller and not modified or scribbled on.
*/
Query *
get_view_query(Relation view)
{
int i;
Assert(view->rd_rel->relkind == RELKIND_VIEW);
for (i = 0; i < view->rd_rules->numLocks; i++)
{
RewriteRule *rule = view->rd_rules->rules[i];
if (rule->event == CMD_SELECT)
{
/* A _RETURN rule should have only one action */
if (list_length(rule->actions) != 1)
elog(ERROR, "invalid _RETURN rule action specification");
return (Query *) linitial(rule->actions);
}
}
elog(ERROR, "failed to find _RETURN rule for view");
return NULL; /* keep compiler quiet */
}
/*
* view_has_instead_trigger - does view have an INSTEAD OF trigger for event?
*
* If it does, we don't want to treat it as auto-updatable. This test can't
* be folded into view_query_is_auto_updatable because it's not an error
* condition.
*/
static bool
view_has_instead_trigger(Relation view, CmdType event)
{
TriggerDesc *trigDesc = view->trigdesc;
switch (event)
{
case CMD_INSERT:
if (trigDesc && trigDesc->trig_insert_instead_row)
return true;
break;
case CMD_UPDATE:
if (trigDesc && trigDesc->trig_update_instead_row)
return true;
break;
case CMD_DELETE:
if (trigDesc && trigDesc->trig_delete_instead_row)
return true;
break;
default:
elog(ERROR, "unrecognized CmdType: %d", (int) event);
break;
}
return false;
}
/*
* view_col_is_auto_updatable - test whether the specified column of a view
* is auto-updatable. Returns NULL (if the column can be updated) or a message
* string giving the reason that it cannot be.
*
* The returned string has not been translated; if it is shown as an error
* message, the caller should apply _() to translate it.
*
* Note that the checks performed here are local to this view. We do not check
* whether the referenced column of the underlying base relation is updatable.
*/
static const char *
view_col_is_auto_updatable(RangeTblRef *rtr, TargetEntry *tle)
{
Var *var = (Var *) tle->expr;
/*
* For now, the only updatable columns we support are those that are Vars
* referring to user columns of the underlying base relation.
*
* The view targetlist may contain resjunk columns (e.g., a view defined
* like "SELECT * FROM t ORDER BY a+b" is auto-updatable) but such columns
* are not auto-updatable, and in fact should never appear in the outer
* query's targetlist.
*/
if (tle->resjunk)
return gettext_noop("Junk view columns are not updatable.");
if (!IsA(var, Var) ||
var->varno != rtr->rtindex ||
var->varlevelsup != 0)
return gettext_noop("View columns that are not columns of their base relation are not updatable.");
if (var->varattno < 0)
return gettext_noop("View columns that refer to system columns are not updatable.");
if (var->varattno == 0)
return gettext_noop("View columns that return whole-row references are not updatable.");
return NULL; /* the view column is updatable */
}
/*
* view_query_is_auto_updatable - test whether the specified view definition
* represents an auto-updatable view. Returns NULL (if the view can be updated)
* or a message string giving the reason that it cannot be.
* The returned string has not been translated; if it is shown as an error
* message, the caller should apply _() to translate it.
*
* If check_cols is true, the view is required to have at least one updatable
* column (necessary for INSERT/UPDATE). Otherwise the view's columns are not
* checked for updatability. See also view_cols_are_auto_updatable.
*
* Note that the checks performed here are only based on the view definition.
* We do not check whether any base relations referred to by the view are
* updatable.
*/
const char *
view_query_is_auto_updatable(Query *viewquery, bool check_cols)
{
RangeTblRef *rtr;
RangeTblEntry *base_rte;
/*----------
* Check if the view is simply updatable. According to SQL-92 this means:
* - No DISTINCT clause.
* - Each TLE is a column reference, and each column appears at most once.
* - FROM contains exactly one base relation.
* - No GROUP BY or HAVING clauses.
* - No set operations (UNION, INTERSECT or EXCEPT).
* - No sub-queries in the WHERE clause that reference the target table.
*
* We ignore that last restriction since it would be complex to enforce
* and there isn't any actual benefit to disallowing sub-queries. (The
* semantic issues that the standard is presumably concerned about don't
* arise in Postgres, since any such sub-query will not see any updates
* executed by the outer query anyway, thanks to MVCC snapshotting.)
*
* We also relax the second restriction by supporting part of SQL:1999
* feature T111, which allows for a mix of updatable and non-updatable
* columns, provided that an INSERT or UPDATE doesn't attempt to assign to
* a non-updatable column.
*
* In addition we impose these constraints, involving features that are
* not part of SQL-92:
* - No CTEs (WITH clauses).
* - No OFFSET or LIMIT clauses (this matches a SQL:2008 restriction).
* - No system columns (including whole-row references) in the tlist.
* - No window functions in the tlist.
* - No set-returning functions in the tlist.
*
* Note that we do these checks without recursively expanding the view.
* If the base relation is a view, we'll recursively deal with it later.
*----------
*/
if (viewquery->distinctClause != NIL)
return gettext_noop("Views containing DISTINCT are not automatically updatable.");
if (viewquery->groupClause != NIL || viewquery->groupingSets)
return gettext_noop("Views containing GROUP BY are not automatically updatable.");
if (viewquery->havingQual != NULL)
return gettext_noop("Views containing HAVING are not automatically updatable.");
if (viewquery->setOperations != NULL)
return gettext_noop("Views containing UNION, INTERSECT, or EXCEPT are not automatically updatable.");
if (viewquery->cteList != NIL)
return gettext_noop("Views containing WITH are not automatically updatable.");
if (viewquery->limitOffset != NULL || viewquery->limitCount != NULL)
return gettext_noop("Views containing LIMIT or OFFSET are not automatically updatable.");
/*
* We must not allow window functions or set returning functions in the
* targetlist. Otherwise we might end up inserting them into the quals of
* the main query. We must also check for aggregates in the targetlist in
* case they appear without a GROUP BY.
*
* These restrictions ensure that each row of the view corresponds to a
* unique row in the underlying base relation.
*/
if (viewquery->hasAggs)
return gettext_noop("Views that return aggregate functions are not automatically updatable.");
if (viewquery->hasWindowFuncs)
return gettext_noop("Views that return window functions are not automatically updatable.");
if (viewquery->hasTargetSRFs)
return gettext_noop("Views that return set-returning functions are not automatically updatable.");
/*
* The view query should select from a single base relation, which must be
* a table or another view.
*/
if (list_length(viewquery->jointree->fromlist) != 1)
return gettext_noop("Views that do not select from a single table or view are not automatically updatable.");
rtr = (RangeTblRef *) linitial(viewquery->jointree->fromlist);
if (!IsA(rtr, RangeTblRef))
return gettext_noop("Views that do not select from a single table or view are not automatically updatable.");
base_rte = rt_fetch(rtr->rtindex, viewquery->rtable);
if (base_rte->rtekind != RTE_RELATION ||
(base_rte->relkind != RELKIND_RELATION &&
base_rte->relkind != RELKIND_FOREIGN_TABLE &&
base_rte->relkind != RELKIND_VIEW &&
base_rte->relkind != RELKIND_PARTITIONED_TABLE))
return gettext_noop("Views that do not select from a single table or view are not automatically updatable.");
if (base_rte->tablesample)
return gettext_noop("Views containing TABLESAMPLE are not automatically updatable.");
/*
* Check that the view has at least one updatable column. This is required
* for INSERT/UPDATE but not for DELETE.
*/
if (check_cols)
{
ListCell *cell;
bool found;
found = false;
foreach(cell, viewquery->targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(cell);
if (view_col_is_auto_updatable(rtr, tle) == NULL)
{
found = true;
break;
}
}
if (!found)
return gettext_noop("Views that have no updatable columns are not automatically updatable.");
}
return NULL; /* the view is updatable */
}
/*
* view_cols_are_auto_updatable - test whether all of the required columns of
* an auto-updatable view are actually updatable. Returns NULL (if all the
* required columns can be updated) or a message string giving the reason that
* they cannot be.
*
* The returned string has not been translated; if it is shown as an error
* message, the caller should apply _() to translate it.
*
* This should be used for INSERT/UPDATE to ensure that we don't attempt to
* assign to any non-updatable columns.
*
* Additionally it may be used to retrieve the set of updatable columns in the
* view, or if one or more of the required columns is not updatable, the name
* of the first offending non-updatable column.
*
* The caller must have already verified that this is an auto-updatable view
* using view_query_is_auto_updatable.
*
* Note that the checks performed here are only based on the view definition.
* We do not check whether the referenced columns of the base relation are
* updatable.
*/
static const char *
view_cols_are_auto_updatable(Query *viewquery,
Bitmapset *required_cols,
Bitmapset **updatable_cols,
char **non_updatable_col)
{
RangeTblRef *rtr;
AttrNumber col;
ListCell *cell;
/*
* The caller should have verified that this view is auto-updatable and so
* there should be a single base relation.
*/
Assert(list_length(viewquery->jointree->fromlist) == 1);
rtr = linitial_node(RangeTblRef, viewquery->jointree->fromlist);
/* Initialize the optional return values */
if (updatable_cols != NULL)
*updatable_cols = NULL;
if (non_updatable_col != NULL)
*non_updatable_col = NULL;
/* Test each view column for updatability */
col = -FirstLowInvalidHeapAttributeNumber;
foreach(cell, viewquery->targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(cell);
const char *col_update_detail;
col++;
col_update_detail = view_col_is_auto_updatable(rtr, tle);
if (col_update_detail == NULL)
{
/* The column is updatable */
if (updatable_cols != NULL)
*updatable_cols = bms_add_member(*updatable_cols, col);
}
else if (bms_is_member(col, required_cols))
{
/* The required column is not updatable */
if (non_updatable_col != NULL)
*non_updatable_col = tle->resname;
return col_update_detail;
}
}
return NULL; /* all the required view columns are updatable */
}
/*
* relation_is_updatable - determine which update events the specified
* relation supports.
*
* Note that views may contain a mix of updatable and non-updatable columns.
* For a view to support INSERT/UPDATE it must have at least one updatable
* column, but there is no such restriction for DELETE. If include_cols is
* non-NULL, then only the specified columns are considered when testing for
* updatability.
*
* This is used for the information_schema views, which have separate concepts
* of "updatable" and "trigger updatable". A relation is "updatable" if it
* can be updated without the need for triggers (either because it has a
* suitable RULE, or because it is simple enough to be automatically updated).
* A relation is "trigger updatable" if it has a suitable INSTEAD OF trigger.
* The SQL standard regards this as not necessarily updatable, presumably
* because there is no way of knowing what the trigger will actually do.
* The information_schema views therefore call this function with
* include_triggers = false. However, other callers might only care whether
* data-modifying SQL will work, so they can pass include_triggers = true
* to have trigger updatability included in the result.
*
* The return value is a bitmask of rule event numbers indicating which of
* the INSERT, UPDATE and DELETE operations are supported. (We do it this way
* so that we can test for UPDATE plus DELETE support in a single call.)
*/
int
relation_is_updatable(Oid reloid,
bool include_triggers,
Bitmapset *include_cols)
{
int events = 0;
Relation rel;
RuleLock *rulelocks;
#define ALL_EVENTS ((1 << CMD_INSERT) | (1 << CMD_UPDATE) | (1 << CMD_DELETE))
rel = try_relation_open(reloid, AccessShareLock, false);
/*
* If the relation doesn't exist, return zero rather than throwing an
* error. This is helpful since scanning an information_schema view under
* MVCC rules can result in referencing rels that have actually been
* deleted already.
*/
if (rel == NULL)
return 0;
/* If the relation is a table, it is always updatable */
/* GPDB: except if it's an external table, which we checked above */
if (rel->rd_rel->relkind == RELKIND_RELATION ||
rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
{
relation_close(rel, AccessShareLock);
return ALL_EVENTS;
}
/* Look for unconditional DO INSTEAD rules, and note supported events */
rulelocks = rel->rd_rules;
if (rulelocks != NULL)
{
int i;
for (i = 0; i < rulelocks->numLocks; i++)
{
if (rulelocks->rules[i]->isInstead &&
rulelocks->rules[i]->qual == NULL)
{
events |= ((1 << rulelocks->rules[i]->event) & ALL_EVENTS);
}
}
/* If we have rules for all events, we're done */
if (events == ALL_EVENTS)
{
relation_close(rel, AccessShareLock);
return events;
}
}
/* Similarly look for INSTEAD OF triggers, if they are to be included */
if (include_triggers)
{
TriggerDesc *trigDesc = rel->trigdesc;
if (trigDesc)
{
if (trigDesc->trig_insert_instead_row)
events |= (1 << CMD_INSERT);
if (trigDesc->trig_update_instead_row)
events |= (1 << CMD_UPDATE);
if (trigDesc->trig_delete_instead_row)
events |= (1 << CMD_DELETE);
/* If we have triggers for all events, we're done */
if (events == ALL_EVENTS)
{
relation_close(rel, AccessShareLock);
return events;
}
}
}
/* If this is a foreign table, check which update events it supports */
if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
{
FdwRoutine *fdwroutine = GetFdwRoutineForRelation(rel, false);
if (fdwroutine->IsForeignRelUpdatable != NULL)
events |= fdwroutine->IsForeignRelUpdatable(rel);
else
{
/* Assume presence of executor functions is sufficient */
if (fdwroutine->ExecForeignInsert != NULL)
events |= (1 << CMD_INSERT);
if (fdwroutine->ExecForeignUpdate != NULL)
events |= (1 << CMD_UPDATE);
if (fdwroutine->ExecForeignDelete != NULL)
events |= (1 << CMD_DELETE);
}
relation_close(rel, AccessShareLock);
return events;
}
/* Check if this is an automatically updatable view */
if (rel->rd_rel->relkind == RELKIND_VIEW)
{
Query *viewquery = get_view_query(rel);
if (view_query_is_auto_updatable(viewquery, false) == NULL)
{
Bitmapset *updatable_cols;
int auto_events;
RangeTblRef *rtr;
RangeTblEntry *base_rte;
Oid baseoid;
/*
* Determine which of the view's columns are updatable. If there
* are none within the set of columns we are looking at, then the
* view doesn't support INSERT/UPDATE, but it may still support
* DELETE.
*/
view_cols_are_auto_updatable(viewquery, NULL,
&updatable_cols, NULL);
if (include_cols != NULL)
updatable_cols = bms_int_members(updatable_cols, include_cols);
if (bms_is_empty(updatable_cols))
auto_events = (1 << CMD_DELETE); /* May support DELETE */
else
auto_events = ALL_EVENTS; /* May support all events */
/*
* The base relation must also support these update commands.
* Tables are always updatable, but for any other kind of base
* relation we must do a recursive check limited to the columns
* referenced by the locally updatable columns in this view.
*/
rtr = (RangeTblRef *) linitial(viewquery->jointree->fromlist);
base_rte = rt_fetch(rtr->rtindex, viewquery->rtable);
Assert(base_rte->rtekind == RTE_RELATION);
if (base_rte->relkind != RELKIND_RELATION &&
base_rte->relkind != RELKIND_PARTITIONED_TABLE)
{
baseoid = base_rte->relid;
include_cols = adjust_view_column_set(updatable_cols,
viewquery->targetList);
auto_events &= relation_is_updatable(baseoid,
include_triggers,
include_cols);
}
events |= auto_events;
}
}
/* If we reach here, the relation may support some update commands */
relation_close(rel, AccessShareLock);
return events;
}
/*
* adjust_view_column_set - map a set of column numbers according to targetlist
*
* This is used with simply-updatable views to map column-permissions sets for
* the view columns onto the matching columns in the underlying base relation.
* The targetlist is expected to be a list of plain Vars of the underlying
* relation (as per the checks above in view_query_is_auto_updatable).
*/
static Bitmapset *
adjust_view_column_set(Bitmapset *cols, List *targetlist)
{
Bitmapset *result = NULL;
int col;
col = -1;
while ((col = bms_next_member(cols, col)) >= 0)
{
/* bit numbers are offset by FirstLowInvalidHeapAttributeNumber */
AttrNumber attno = col + FirstLowInvalidHeapAttributeNumber;
if (attno == InvalidAttrNumber)
{
/*
* There's a whole-row reference to the view. For permissions
* purposes, treat it as a reference to each column available from
* the view. (We should *not* convert this to a whole-row
* reference to the base relation, since the view may not touch
* all columns of the base relation.)
*/
ListCell *lc;
foreach(lc, targetlist)
{
TargetEntry *tle = lfirst_node(TargetEntry, lc);
Var *var;
if (tle->resjunk)
continue;
var = castNode(Var, tle->expr);
result = bms_add_member(result,
var->varattno - FirstLowInvalidHeapAttributeNumber);
}
}
else
{
/*
* Views do not have system columns, so we do not expect to see
* any other system attnos here. If we do find one, the error
* case will apply.
*/
TargetEntry *tle = get_tle_by_resno(targetlist, attno);
if (tle != NULL && !tle->resjunk && IsA(tle->expr, Var))
{
Var *var = (Var *) tle->expr;
result = bms_add_member(result,
var->varattno - FirstLowInvalidHeapAttributeNumber);
}
else
elog(ERROR, "attribute number %d not found in view targetlist",
attno);
}
}
return result;
}
/*
* rewriteTargetView -
* Attempt to rewrite a query where the target relation is a view, so that
* the view's base relation becomes the target relation.
*
* Note that the base relation here may itself be a view, which may or may not
* have INSTEAD OF triggers or rules to handle the update. That is handled by
* the recursion in RewriteQuery.
*/
static Query *
rewriteTargetView(Query *parsetree, Relation view)
{
Query *viewquery;
const char *auto_update_detail;
RangeTblRef *rtr;
int base_rt_index;
int new_rt_index;
RangeTblEntry *base_rte;
RangeTblEntry *view_rte;
RangeTblEntry *new_rte;
Relation base_rel;
List *view_targetlist;
ListCell *lc;
/*
* Get the Query from the view's ON SELECT rule. We're going to munge the
* Query to change the view's base relation into the target relation,
* along with various other changes along the way, so we need to make a
* copy of it (get_view_query() returns a pointer into the relcache, so we
* have to treat it as read-only).
*/
viewquery = copyObject(get_view_query(view));
/* The view must be updatable, else fail */
auto_update_detail =
view_query_is_auto_updatable(viewquery,
parsetree->commandType != CMD_DELETE);
if (auto_update_detail)
{
/* messages here should match execMain.c's CheckValidResultRel */
switch (parsetree->commandType)
{
case CMD_INSERT:
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("cannot insert into view \"%s\"",
RelationGetRelationName(view)),
errdetail_internal("%s", _(auto_update_detail)),
errhint("To enable inserting into the view, provide an INSTEAD OF INSERT trigger or an unconditional ON INSERT DO INSTEAD rule.")));
break;
case CMD_UPDATE:
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("cannot update view \"%s\"",
RelationGetRelationName(view)),
errdetail_internal("%s", _(auto_update_detail)),
errhint("To enable updating the view, provide an INSTEAD OF UPDATE trigger or an unconditional ON UPDATE DO INSTEAD rule.")));
break;
case CMD_DELETE:
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("cannot delete from view \"%s\"",
RelationGetRelationName(view)),
errdetail_internal("%s", _(auto_update_detail)),
errhint("To enable deleting from the view, provide an INSTEAD OF DELETE trigger or an unconditional ON DELETE DO INSTEAD rule.")));
break;
default:
elog(ERROR, "unrecognized CmdType: %d",
(int) parsetree->commandType);
break;
}
}
/*
* For INSERT/UPDATE the modified columns must all be updatable. Note that
* we get the modified columns from the query's targetlist, not from the
* result RTE's insertedCols and/or updatedCols set, since
* rewriteTargetListIU may have added additional targetlist entries for
* view defaults, and these must also be updatable.
*/
if (parsetree->commandType != CMD_DELETE)
{
Bitmapset *modified_cols = NULL;
char *non_updatable_col;
foreach(lc, parsetree->targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
if (!tle->resjunk)
modified_cols = bms_add_member(modified_cols,
tle->resno - FirstLowInvalidHeapAttributeNumber);
}
if (parsetree->onConflict)
{
foreach(lc, parsetree->onConflict->onConflictSet)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
if (!tle->resjunk)
modified_cols = bms_add_member(modified_cols,
tle->resno - FirstLowInvalidHeapAttributeNumber);
}
}
auto_update_detail = view_cols_are_auto_updatable(viewquery,
modified_cols,
NULL,
&non_updatable_col);
if (auto_update_detail)
{
/*
* This is a different error, caused by an attempt to update a
* non-updatable column in an otherwise updatable view.
*/
switch (parsetree->commandType)
{
case CMD_INSERT:
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot insert into column \"%s\" of view \"%s\"",
non_updatable_col,
RelationGetRelationName(view)),
errdetail_internal("%s", _(auto_update_detail))));
break;
case CMD_UPDATE:
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot update column \"%s\" of view \"%s\"",
non_updatable_col,
RelationGetRelationName(view)),
errdetail_internal("%s", _(auto_update_detail))));
break;
default:
elog(ERROR, "unrecognized CmdType: %d",
(int) parsetree->commandType);
break;
}
}
}
/* Locate RTE describing the view in the outer query */
view_rte = rt_fetch(parsetree->resultRelation, parsetree->rtable);
/*
* If we get here, view_query_is_auto_updatable() has verified that the
* view contains a single base relation.
*/
Assert(list_length(viewquery->jointree->fromlist) == 1);
rtr = linitial_node(RangeTblRef, viewquery->jointree->fromlist);
base_rt_index = rtr->rtindex;
base_rte = rt_fetch(base_rt_index, viewquery->rtable);
Assert(base_rte->rtekind == RTE_RELATION);
/*
* Up to now, the base relation hasn't been touched at all in our query.
* We need to acquire lock on it before we try to do anything with it.
* (The subsequent recursive call of RewriteQuery will suppose that we
* already have the right lock!) Since it will become the query target
* relation, RowExclusiveLock is always the right thing.
*/
base_rel = table_open(base_rte->relid, RowExclusiveLock);
/*
* While we have the relation open, update the RTE's relkind, just in case
* it changed since this view was made (cf. AcquireRewriteLocks).
*/
base_rte->relkind = base_rel->rd_rel->relkind;
/*
* If the view query contains any sublink subqueries then we need to also
* acquire locks on any relations they refer to. We know that there won't
* be any subqueries in the range table or CTEs, so we can skip those, as
* in AcquireRewriteLocks.
*/
if (viewquery->hasSubLinks)
{
acquireLocksOnSubLinks_context context;
context.for_execute = true;
query_tree_walker(viewquery, acquireLocksOnSubLinks, &context,
QTW_IGNORE_RC_SUBQUERIES);
}
/*
* Create a new target RTE describing the base relation, and add it to the
* outer query's rangetable. (What's happening in the next few steps is
* very much like what the planner would do to "pull up" the view into the
* outer query. Perhaps someday we should refactor things enough so that
* we can share code with the planner.)
*
* Be sure to set rellockmode to the correct thing for the target table.
* Since we copied the whole viewquery above, we can just scribble on
* base_rte instead of copying it.
*/
new_rte = base_rte;
new_rte->rellockmode = RowExclusiveLock;
parsetree->rtable = lappend(parsetree->rtable, new_rte);
new_rt_index = list_length(parsetree->rtable);
/*
* INSERTs never inherit. For UPDATE/DELETE, we use the view query's
* inheritance flag for the base relation.
*/
if (parsetree->commandType == CMD_INSERT)
new_rte->inh = false;
/*
* Adjust the view's targetlist Vars to reference the new target RTE, ie
* make their varnos be new_rt_index instead of base_rt_index. There can
* be no Vars for other rels in the tlist, so this is sufficient to pull
* up the tlist expressions for use in the outer query. The tlist will
* provide the replacement expressions used by ReplaceVarsFromTargetList
* below.
*/
view_targetlist = viewquery->targetList;
ChangeVarNodes((Node *) view_targetlist,
base_rt_index,
new_rt_index,
0);
/*
* Mark the new target RTE for the permissions checks that we want to
* enforce against the view owner, as distinct from the query caller. At
* the relation level, require the same INSERT/UPDATE/DELETE permissions
* that the query caller needs against the view. We drop the ACL_SELECT
* bit that is presumably in new_rte->requiredPerms initially.
*
* Note: the original view RTE remains in the query's rangetable list.
* Although it will be unused in the query plan, we need it there so that
* the executor still performs appropriate permissions checks for the
* query caller's use of the view.
*/
new_rte->checkAsUser = view->rd_rel->relowner;
new_rte->requiredPerms = view_rte->requiredPerms;
/*
* Now for the per-column permissions bits.
*
* Initially, new_rte contains selectedCols permission check bits for all
* base-rel columns referenced by the view, but since the view is a SELECT
* query its insertedCols/updatedCols is empty. We set insertedCols and
* updatedCols to include all the columns the outer query is trying to
* modify, adjusting the column numbers as needed. But we leave
* selectedCols as-is, so the view owner must have read permission for all
* columns used in the view definition, even if some of them are not read
* by the outer query. We could try to limit selectedCols to only columns
* used in the transformed query, but that does not correspond to what
* happens in ordinary SELECT usage of a view: all referenced columns must
* have read permission, even if optimization finds that some of them can
* be discarded during query transformation. The flattening we're doing
* here is an optional optimization, too. (If you are unpersuaded and
* want to change this, note that applying adjust_view_column_set to
* view_rte->selectedCols is clearly *not* the right answer, since that
* neglects base-rel columns used in the view's WHERE quals.)
*
* This step needs the modified view targetlist, so we have to do things
* in this order.
*/
Assert(bms_is_empty(new_rte->insertedCols) &&
bms_is_empty(new_rte->updatedCols));
new_rte->insertedCols = adjust_view_column_set(view_rte->insertedCols,
view_targetlist);
new_rte->updatedCols = adjust_view_column_set(view_rte->updatedCols,
view_targetlist);
/*
* Move any security barrier quals from the view RTE onto the new target
* RTE. Any such quals should now apply to the new target RTE and will
* not reference the original view RTE in the rewritten query.
*/
new_rte->securityQuals = view_rte->securityQuals;
view_rte->securityQuals = NIL;
/*
* Now update all Vars in the outer query that reference the view to
* reference the appropriate column of the base relation instead.
*/
parsetree = (Query *)
ReplaceVarsFromTargetList((Node *) parsetree,
parsetree->resultRelation,
0,
view_rte,
view_targetlist,
REPLACEVARS_REPORT_ERROR,
0,
&parsetree->hasSubLinks);
/*
* Update all other RTI references in the query that point to the view
* (for example, parsetree->resultRelation itself) to point to the new
* base relation instead. Vars will not be affected since none of them
* reference parsetree->resultRelation any longer.
*/
ChangeVarNodes((Node *) parsetree,
parsetree->resultRelation,
new_rt_index,
0);
Assert(parsetree->resultRelation == new_rt_index);
/*
* For INSERT/UPDATE we must also update resnos in the targetlist to refer
* to columns of the base relation, since those indicate the target
* columns to be affected.
*
* Note that this destroys the resno ordering of the targetlist, but that
* will be fixed when we recurse through rewriteQuery, which will invoke
* rewriteTargetListIU again on the updated targetlist.
*/
if (parsetree->commandType != CMD_DELETE)
{
foreach(lc, parsetree->targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
TargetEntry *view_tle;
if (tle->resjunk)
continue;
view_tle = get_tle_by_resno(view_targetlist, tle->resno);
if (view_tle != NULL && !view_tle->resjunk && IsA(view_tle->expr, Var))
tle->resno = ((Var *) view_tle->expr)->varattno;
else
elog(ERROR, "attribute number %d not found in view targetlist",
tle->resno);
}
}
/*
* For INSERT .. ON CONFLICT .. DO UPDATE, we must also update assorted
* stuff in the onConflict data structure.
*/
if (parsetree->onConflict &&
parsetree->onConflict->action == ONCONFLICT_UPDATE)
{
Index old_exclRelIndex,
new_exclRelIndex;
RangeTblEntry *new_exclRte;
List *tmp_tlist;
/*
* Like the INSERT/UPDATE code above, update the resnos in the
* auxiliary UPDATE targetlist to refer to columns of the base
* relation.
*/
foreach(lc, parsetree->onConflict->onConflictSet)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
TargetEntry *view_tle;
if (tle->resjunk)
continue;
view_tle = get_tle_by_resno(view_targetlist, tle->resno);
if (view_tle != NULL && !view_tle->resjunk && IsA(view_tle->expr, Var))
tle->resno = ((Var *) view_tle->expr)->varattno;
else
elog(ERROR, "attribute number %d not found in view targetlist",
tle->resno);
}
/*
* Also, create a new RTE for the EXCLUDED pseudo-relation, using the
* query's new base rel (which may well have a different column list
* from the view, hence we need a new column alias list). This should
* match transformOnConflictClause. In particular, note that the
* relkind is set to composite to signal that we're not dealing with
* an actual relation, and no permissions checks are wanted.
*/
old_exclRelIndex = parsetree->onConflict->exclRelIndex;
new_exclRte = addRangeTableEntryForRelation(make_parsestate(NULL),
base_rel,
RowExclusiveLock,
makeAlias("excluded", NIL),
false, false);
new_exclRte->relkind = RELKIND_COMPOSITE_TYPE;
new_exclRte->requiredPerms = 0;
/* other permissions fields in new_exclRte are already empty */
parsetree->rtable = lappend(parsetree->rtable, new_exclRte);
new_exclRelIndex = parsetree->onConflict->exclRelIndex =
list_length(parsetree->rtable);
/*
* Replace the targetlist for the EXCLUDED pseudo-relation with a new
* one, representing the columns from the new base relation.
*/
parsetree->onConflict->exclRelTlist =
BuildOnConflictExcludedTargetlist(base_rel, new_exclRelIndex);
/*
* Update all Vars in the ON CONFLICT clause that refer to the old
* EXCLUDED pseudo-relation. We want to use the column mappings
* defined in the view targetlist, but we need the outputs to refer to
* the new EXCLUDED pseudo-relation rather than the new target RTE.
* Also notice that "EXCLUDED.*" will be expanded using the view's
* rowtype, which seems correct.
*/
tmp_tlist = copyObject(view_targetlist);
ChangeVarNodes((Node *) tmp_tlist, new_rt_index,
new_exclRelIndex, 0);
parsetree->onConflict = (OnConflictExpr *)
ReplaceVarsFromTargetList((Node *) parsetree->onConflict,
old_exclRelIndex,
0,
view_rte,
tmp_tlist,
REPLACEVARS_REPORT_ERROR,
0,
&parsetree->hasSubLinks);
}
/*
* For UPDATE/DELETE, pull up any WHERE quals from the view. We know that
* any Vars in the quals must reference the one base relation, so we need
* only adjust their varnos to reference the new target (just the same as
* we did with the view targetlist).
*
* If it's a security-barrier view, its WHERE quals must be applied before
* quals from the outer query, so we attach them to the RTE as security
* barrier quals rather than adding them to the main WHERE clause.
*
* For INSERT, the view's quals can be ignored in the main query.
*/
if (parsetree->commandType != CMD_INSERT &&
viewquery->jointree->quals != NULL)
{
Node *viewqual = (Node *) viewquery->jointree->quals;
/*
* Even though we copied viewquery already at the top of this
* function, we must duplicate the viewqual again here, because we may
* need to use the quals again below for a WithCheckOption clause.
*/
viewqual = copyObject(viewqual);
ChangeVarNodes(viewqual, base_rt_index, new_rt_index, 0);
if (RelationIsSecurityView(view))
{
/*
* The view's quals go in front of existing barrier quals: those
* would have come from an outer level of security-barrier view,
* and so must get evaluated later.
*
* Note: the parsetree has been mutated, so the new_rte pointer is
* stale and needs to be re-computed.
*/
new_rte = rt_fetch(new_rt_index, parsetree->rtable);
new_rte->securityQuals = lcons(viewqual, new_rte->securityQuals);
/*
* Do not set parsetree->hasRowSecurity, because these aren't RLS
* conditions (they aren't affected by enabling/disabling RLS).
*/
/*
* Make sure that the query is marked correctly if the added qual
* has sublinks.
*/
if (!parsetree->hasSubLinks)
parsetree->hasSubLinks = checkExprHasSubLink(viewqual);
}
else
AddQual(parsetree, (Node *) viewqual);
}
/*
* For INSERT/UPDATE, if the view has the WITH CHECK OPTION, or any parent
* view specified WITH CASCADED CHECK OPTION, add the quals from the view
* to the query's withCheckOptions list.
*/
if (parsetree->commandType != CMD_DELETE)
{
bool has_wco = RelationHasCheckOption(view);
bool cascaded = RelationHasCascadedCheckOption(view);
/*
* If the parent view has a cascaded check option, treat this view as
* if it also had a cascaded check option.
*
* New WithCheckOptions are added to the start of the list, so if
* there is a cascaded check option, it will be the first item in the
* list.
*/
if (parsetree->withCheckOptions != NIL)
{
WithCheckOption *parent_wco =
(WithCheckOption *) linitial(parsetree->withCheckOptions);
if (parent_wco->cascaded)
{
has_wco = true;
cascaded = true;
}
}
/*
* Add the new WithCheckOption to the start of the list, so that
* checks on inner views are run before checks on outer views, as
* required by the SQL standard.
*
* If the new check is CASCADED, we need to add it even if this view
* has no quals, since there may be quals on child views. A LOCAL
* check can be omitted if this view has no quals.
*/
if (has_wco && (cascaded || viewquery->jointree->quals != NULL))
{
WithCheckOption *wco;
wco = makeNode(WithCheckOption);
wco->kind = WCO_VIEW_CHECK;
wco->relname = pstrdup(RelationGetRelationName(view));
wco->polname = NULL;
wco->qual = NULL;
wco->cascaded = cascaded;
parsetree->withCheckOptions = lcons(wco,
parsetree->withCheckOptions);
if (viewquery->jointree->quals != NULL)
{
wco->qual = (Node *) viewquery->jointree->quals;
ChangeVarNodes(wco->qual, base_rt_index, new_rt_index, 0);
/*
* Make sure that the query is marked correctly if the added
* qual has sublinks. We can skip this check if the query is
* already marked, or if the command is an UPDATE, in which
* case the same qual will have already been added, and this
* check will already have been done.
*/
if (!parsetree->hasSubLinks &&
parsetree->commandType != CMD_UPDATE)
parsetree->hasSubLinks = checkExprHasSubLink(wco->qual);
}
}
}
table_close(base_rel, NoLock);
return parsetree;
}
/*
* 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;
bool updatableview = false;
Query *qual_product = NULL;
List *rewritten = NIL;
ListCell *lc1;
/*
* First, recursively process any insert/update/delete statements in WITH
* clauses. (We have to do this first because the WITH clauses may get
* copied into rule actions below.)
*/
foreach(lc1, parsetree->cteList)
{
CommonTableExpr *cte = lfirst_node(CommonTableExpr, lc1);
Query *ctequery = castNode(Query, cte->ctequery);
List *newstuff;
if (ctequery->commandType == CMD_SELECT)
continue;
newstuff = RewriteQuery(ctequery, rewrite_events);
/*
* Currently we can only handle unconditional, single-statement DO
* INSTEAD rules correctly; we have to get exactly one Query out of
* the rewrite operation to stuff back into the CTE node.
*/
if (list_length(newstuff) == 1)
{
/* Push the single Query back into the CTE node */
ctequery = linitial_node(Query, newstuff);
/* WITH queries should never be canSetTag */
Assert(!ctequery->canSetTag);
cte->ctequery = (Node *) ctequery;
}
else if (newstuff == NIL)
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("DO INSTEAD NOTHING rules are not supported for data-modifying statements in WITH")));
}
else
{
ListCell *lc2;
/* examine queries to determine which error message to issue */
foreach(lc2, newstuff)
{
Query *q = (Query *) lfirst(lc2);
if (q->querySource == QSRC_QUAL_INSTEAD_RULE)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("conditional DO INSTEAD rules are not supported for data-modifying statements in WITH")));
if (q->querySource == QSRC_NON_INSTEAD_RULE)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("DO ALSO rules are not supported for data-modifying statements in WITH")));
}
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("multi-statement DO INSTEAD rules are not supported for data-modifying statements in WITH")));
}
}
/*
* 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 && event != CMD_UTILITY)
{
int result_relation;
RangeTblEntry *rt_entry;
Relation rt_entry_relation;
List *locks;
List *product_queries;
bool hasUpdate = false;
int values_rte_index = 0;
bool defaults_remaining = false;
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 = table_open(rt_entry->relid, NoLock);
/*
* Rewrite the targetlist as needed for the command type.
*/
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;
values_rte_index = rtr->rtindex;
}
}
}
if (values_rte)
{
/* Process the main targetlist ... */
parsetree->targetList = rewriteTargetListIU(parsetree->targetList,
parsetree->commandType,
parsetree->override,
rt_entry_relation,
parsetree->resultRelation);
/* ... and the VALUES expression lists */
if (!rewriteValuesRTE(parsetree, values_rte, values_rte_index,
rt_entry_relation, false))
defaults_remaining = true;
}
else
{
/* Process just the main targetlist */
parsetree->targetList =
rewriteTargetListIU(parsetree->targetList,
parsetree->commandType,
parsetree->override,
rt_entry_relation,
parsetree->resultRelation);
}
if (parsetree->onConflict &&
parsetree->onConflict->action == ONCONFLICT_UPDATE)
{
parsetree->onConflict->onConflictSet =
rewriteTargetListIU(parsetree->onConflict->onConflictSet,
CMD_UPDATE,
parsetree->override,
rt_entry_relation,
parsetree->resultRelation);
}
}
else if (event == CMD_UPDATE)
{
parsetree->targetList =
rewriteTargetListIU(parsetree->targetList,
parsetree->commandType,
parsetree->override,
rt_entry_relation,
parsetree->resultRelation);
}
else if (event == CMD_DELETE)
{
/* Nothing to do here */
}
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, &hasUpdate);
product_queries = fireRules(parsetree,
result_relation,
event,
locks,
&instead,
&returning,
&qual_product);
/*
* If we have a VALUES RTE with any remaining untouched DEFAULT items,
* and we got any product queries, finalize the VALUES RTE for each
* product query (replacing the remaining DEFAULT items with NULLs).
* We don't do this for the original query, because we know that it
* must be an auto-insert on a view, and so should use the base
* relation's defaults for any remaining DEFAULT items.
*/
if (defaults_remaining && product_queries != NIL)
{
ListCell *n;
/*
* Each product query has its own copy of the VALUES RTE at the
* same index in the rangetable, so we must finalize each one.
*/
foreach(n, product_queries)
{
Query *pt = (Query *) lfirst(n);
RangeTblEntry *values_rte = rt_fetch(values_rte_index,
pt->rtable);
rewriteValuesRTE(pt, values_rte, values_rte_index,
rt_entry_relation,
true); /* Force remaining defaults to NULL */
}
}
/*
* If there were no INSTEAD rules, and the target relation is a view
* without any INSTEAD OF triggers, see if the view can be
* automatically updated. If so, we perform the necessary query
* transformation here and add the resulting query to the
* product_queries list, so that it gets recursively rewritten if
* necessary.
*/
if (!instead && qual_product == NULL &&
rt_entry_relation->rd_rel->relkind == RELKIND_VIEW &&
!view_has_instead_trigger(rt_entry_relation, event))
{
/*
* This throws an error if the view can't be automatically
* updated, but that's OK since the query would fail at runtime
* anyway.
*/
parsetree = rewriteTargetView(parsetree, rt_entry_relation);
/*
* At this point product_queries contains any DO ALSO rule
* actions. Add the rewritten query before or after those. This
* must match the handling the original query would have gotten
* below, if we allowed it to be included again.
*/
if (parsetree->commandType == CMD_INSERT)
product_queries = lcons(parsetree, product_queries);
else
product_queries = lappend(product_queries, parsetree);
/*
* Set the "instead" flag, as if there had been an unqualified
* INSTEAD, to prevent the original query from being included a
* second time below. The transformation will have rewritten any
* RETURNING list, so we can also set "returning" to forestall
* throwing an error below.
*/
instead = true;
returning = true;
updatableview = true;
}
/*
* 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;
}
}
/*
* Updatable views are supported by ON CONFLICT, so don't prevent that
* case from proceeding
*/
if (parsetree->onConflict &&
(product_queries != NIL || hasUpdate) &&
!updatableview)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("INSERT with ON CONFLICT clause cannot be used with table that has INSERT or UPDATE rules")));
table_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);
}
}
/*
* If the original query has a CTE list, and we generated more than one
* non-utility result query, we have to fail because we'll have copied the
* CTE list into each result query. That would break the expectation of
* single evaluation of CTEs. This could possibly be fixed by
* restructuring so that a CTE list can be shared across multiple Query
* and PlannableStatement nodes.
*/
if (parsetree->cteList != NIL)
{
int qcount = 0;
foreach(lc1, rewritten)
{
Query *q = (Query *) lfirst(lc1);
if (q->commandType != CMD_UTILITY)
qcount++;
}
if (qcount > 1)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("WITH cannot be used in a query that is rewritten by rules into multiple queries")));
}
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)
{
uint64 input_query_id = parsetree->queryId;
List *querylist;
List *results;
ListCell *l;
CmdType origCmdType;
bool foundOriginalQuery;
Query *lastInstead;
/*
* This function is only applied to top-level original queries
*/
Assert(parsetree->querySource == QSRC_ORIGINAL);
Assert(parsetree->canSetTag);
/*
* 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
*
* This is also a handy place to mark each query with the original queryId
*/
results = NIL;
foreach(l, querylist)
{
Query *query = (Query *) lfirst(l);
query = fireRIRrules(query, NIL);
query->queryId = input_query_id;
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;
}
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