diff options
Diffstat (limited to 'src/backend/commands/tablecmds.c')
| -rw-r--r-- | src/backend/commands/tablecmds.c | 90 |
1 files changed, 50 insertions, 40 deletions
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index cd2324a7c6..301420c401 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.238 2008/01/01 19:45:49 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.239 2008/01/02 23:34:42 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -194,6 +194,7 @@ static void validateForeignKeyConstraint(FkConstraint *fkconstraint, Relation rel, Relation pkrel, Oid constraintOid); static void createForeignKeyTriggers(Relation rel, FkConstraint *fkconstraint, Oid constraintOid); +static void CheckTableNotInUse(Relation rel); static void ATController(Relation rel, List *cmds, bool recurse); static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd, bool recurse, bool recursing); @@ -599,13 +600,6 @@ ExecuteTruncate(TruncateStmt *stmt) #endif /* - * Also check for pending AFTER trigger events on the target relations. We - * can't just leave those be, since they will try to fetch tuples that the - * TRUNCATE removes. - */ - AfterTriggerCheckTruncate(relids); - - /* * OK, truncate each table. */ foreach(cell, rels) @@ -685,6 +679,17 @@ truncate_check_rel(Relation rel) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot truncate temporary tables of other sessions"))); + + /* + * Also check for pending AFTER trigger events on the relation. We can't + * just leave those be, since they will try to fetch tuples that the + * TRUNCATE removes. + */ + if (AfterTriggerPendingOnRel(RelationGetRelid(rel))) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("cannot truncate table \"%s\" because it has pending trigger events", + RelationGetRelationName(rel)))); } /*---------- @@ -1749,20 +1754,35 @@ void AlterTable(AlterTableStmt *stmt) { Relation rel = relation_openrv(stmt->relation, AccessExclusiveLock); + + CheckTableNotInUse(rel); + + ATController(rel, stmt->cmds, interpretInhOption(stmt->relation->inhOpt)); +} + +/* + * Disallow ALTER TABLE when the current backend has any open reference to + * it besides the one we just got (such as an open cursor or active plan); + * our AccessExclusiveLock doesn't protect us against stomping on our own + * foot, only other people's feet! + * + * Note: the only case known to cause serious trouble is ALTER COLUMN TYPE, + * and some changes are obviously pretty benign, so this could possibly be + * relaxed to only error out for certain types of alterations. But the + * use-case for allowing any of these things is not obvious, so we won't + * work hard at it for now. + * + * We also reject ALTER TABLE if there are any pending AFTER trigger events + * for the rel. This is certainly necessary for the rewriting variants of + * ALTER TABLE, because they don't preserve tuple TIDs and so the pending + * events would try to fetch the wrong tuples. It might be overly cautious + * in other cases, but again it seems better to err on the side of paranoia. + */ +static void +CheckTableNotInUse(Relation rel) +{ int expected_refcnt; - /* - * Disallow ALTER TABLE when the current backend has any open reference to - * it besides the one we just got (such as an open cursor or active plan); - * our AccessExclusiveLock doesn't protect us against stomping on our own - * foot, only other people's feet! - * - * Note: the only case known to cause serious trouble is ALTER COLUMN - * TYPE, and some changes are obviously pretty benign, so this could - * possibly be relaxed to only error out for certain types of alterations. - * But the use-case for allowing any of these things is not obvious, so we - * won't work hard at it for now. - */ expected_refcnt = rel->rd_isnailed ? 2 : 1; if (rel->rd_refcnt != expected_refcnt) ereport(ERROR, @@ -1770,7 +1790,11 @@ AlterTable(AlterTableStmt *stmt) errmsg("relation \"%s\" is being used by active queries in this session", RelationGetRelationName(rel)))); - ATController(rel, stmt->cmds, interpretInhOption(stmt->relation->inhOpt)); + if (AfterTriggerPendingOnRel(RelationGetRelid(rel))) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("cannot alter table \"%s\" because it has pending trigger events", + RelationGetRelationName(rel)))); } /* @@ -1781,7 +1805,8 @@ AlterTable(AlterTableStmt *stmt) * We do not reject if the relation is already open, because it's quite * likely that one or more layers of caller have it open. That means it * is unsafe to use this entry point for alterations that could break - * existing query plans. + * existing query plans. On the assumption it's not used for such, we + * don't have to reject pending AFTER triggers, either. */ void AlterTableInternal(Oid relid, List *cmds, bool recurse) @@ -2784,12 +2809,7 @@ ATSimpleRecursion(List **wqueue, Relation rel, if (childrelid == relid) continue; childrel = relation_open(childrelid, AccessExclusiveLock); - /* check for child relation in use in this session */ - if (childrel->rd_refcnt != 1) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("relation \"%s\" is being used by active queries in this session", - RelationGetRelationName(childrel)))); + CheckTableNotInUse(childrel); ATPrepCmd(wqueue, childrel, cmd, false, true); relation_close(childrel, NoLock); } @@ -2821,12 +2841,7 @@ ATOneLevelRecursion(List **wqueue, Relation rel, Relation childrel; childrel = relation_open(childrelid, AccessExclusiveLock); - /* check for child relation in use in this session */ - if (childrel->rd_refcnt != 1) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("relation \"%s\" is being used by active queries in this session", - RelationGetRelationName(childrel)))); + CheckTableNotInUse(childrel); ATPrepCmd(wqueue, childrel, cmd, true, true); relation_close(childrel, NoLock); } @@ -3655,12 +3670,7 @@ ATExecDropColumn(Relation rel, const char *colName, Form_pg_attribute childatt; childrel = heap_open(childrelid, AccessExclusiveLock); - /* check for child relation in use in this session */ - if (childrel->rd_refcnt != 1) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("relation \"%s\" is being used by active queries in this session", - RelationGetRelationName(childrel)))); + CheckTableNotInUse(childrel); tuple = SearchSysCacheCopyAttName(childrelid, colName); if (!HeapTupleIsValid(tuple)) /* shouldn't happen */ |