diff options
Diffstat (limited to 'src/backend/commands/trigger.c')
| -rw-r--r-- | src/backend/commands/trigger.c | 119 |
1 files changed, 118 insertions, 1 deletions
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c index c00b4bebac8..b826297a718 100644 --- a/src/backend/commands/trigger.c +++ b/src/backend/commands/trigger.c @@ -7,7 +7,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/commands/trigger.c,v 1.114 2002/04/19 16:36:08 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/commands/trigger.c,v 1.115 2002/04/26 19:29:47 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -504,6 +504,123 @@ RelationRemoveTriggers(Relation rel) } /* + * renametrig - changes the name of a trigger on a relation + * + * trigger name is changed in trigger catalog. + * No record of the previous name is kept. + * + * get proper relrelation from relation catalog (if not arg) + * scan trigger catalog + * for name conflict (within rel) + * for original trigger (if not arg) + * modify tgname in trigger tuple + * insert modified trigger in trigger catalog + * delete original trigger from trigger catalog + */ +void +renametrig(Oid relid, + const char *oldname, + const char *newname) +{ + Relation targetrel; + Relation tgrel; + HeapTuple tuple; + SysScanDesc tgscan; + ScanKeyData key; + bool found = FALSE; + Relation idescs[Num_pg_trigger_indices]; + + /* + * Grab an exclusive lock on the target table, which we will NOT + * release until end of transaction. + */ + targetrel = heap_open(relid, AccessExclusiveLock); + + /* + * Scan pg_trigger twice for existing triggers on relation. We do this in + * order to ensure a trigger does not exist with newname (The unique index + * on tgrelid/tgname would complain anyway) and to ensure a trigger does + * exist with oldname. + * + * NOTE that this is cool only because we have AccessExclusiveLock on the + * relation, so the trigger set won't be changing underneath us. + */ + tgrel = heap_openr(TriggerRelationName, RowExclusiveLock); + + /* + * First pass -- look for name conflict + */ + ScanKeyEntryInitialize(&key, 0, + Anum_pg_trigger_tgrelid, + F_OIDEQ, + ObjectIdGetDatum(relid)); + tgscan = systable_beginscan(tgrel, TriggerRelidNameIndex, true, + SnapshotNow, 1, &key); + while (HeapTupleIsValid(tuple = systable_getnext(tgscan))) + { + Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(tuple); + + if (namestrcmp(&(pg_trigger->tgname), newname) == 0) + elog(ERROR, "renametrig: trigger %s already defined on relation %s", + newname, RelationGetRelationName(targetrel)); + } + systable_endscan(tgscan); + + /* + * Second pass -- look for trigger existing with oldname and update + */ + ScanKeyEntryInitialize(&key, 0, + Anum_pg_trigger_tgrelid, + F_OIDEQ, + ObjectIdGetDatum(relid)); + tgscan = systable_beginscan(tgrel, TriggerRelidNameIndex, true, + SnapshotNow, 1, &key); + while (HeapTupleIsValid(tuple = systable_getnext(tgscan))) + { + Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(tuple); + + if (namestrcmp(&(pg_trigger->tgname), oldname) == 0) + { + /* + * Update pg_trigger tuple with new tgname. + * (Scribbling on tuple is OK because it's a copy...) + */ + namestrcpy(&(pg_trigger->tgname), newname); + simple_heap_update(tgrel, &tuple->t_self, tuple); + + /* + * keep system catalog indices current + */ + CatalogOpenIndices(Num_pg_trigger_indices, Name_pg_trigger_indices, idescs); + CatalogIndexInsert(idescs, Num_pg_trigger_indices, tgrel, tuple); + CatalogCloseIndices(Num_pg_trigger_indices, idescs); + + /* + * Invalidate relation's relcache entry so that other + * backends (and this one too!) are sent SI message to make them + * rebuild relcache entries. + */ + CacheInvalidateRelcache(relid); + + found = TRUE; + break; + } + } + systable_endscan(tgscan); + + heap_close(tgrel, RowExclusiveLock); + + if (!found) + elog(ERROR, "renametrig: trigger %s not defined on relation %s", + oldname, RelationGetRelationName(targetrel)); + + /* + * Close rel, but keep exclusive lock! + */ + heap_close(targetrel, NoLock); +} + +/* * Build trigger data to attach to the given relcache entry. * * Note that trigger data must be allocated in CacheMemoryContext |