Attached a rebased patch with the suggested "ONLY ON" change.
Regards
Arne
________________________________
From: Arne Roland <a.rol...@index.de>
Sent: Monday, March 29, 2021 9:37:53 AM
To: David Steele; Alvaro Herrera
Cc: Pg Hackers
Subject: Re: Rename of triggers for partitioned tables
David Steele wrote:
> Arne, thoughts on Álvaro's comments?
>
> Marking this patch as Waiting for Author.
Thank you for the reminder. I was to absorbed by other tasks. I should be more
present in the upcoming weeks.
> I think you did not register the patch in commitfest, so I did that for
> you: https://commitfest.postgresql.org/32/2943/
Thank you! I should have done that.
> As you say, triggers on children don't necessarily have to have the same
> name as on parent; this already happens when the trigger is renamed in
> the child table but not on parent. In that situation the search on the
> child will fail, which will cause the whole thing to fail I think.
>
> We now have the column pg_trigger.tgparentid, and I think it would be
> better (more reliable) to search for the trigger in the child by the
> tgparentid column instead, rather than by name.
The last patch already checks tgparentid and errors out if either of those do
not match.
The reasoning behind that was, that I don't see a clear reasonable way to
handle this scenario.
If the user choose to rename the child trigger, I am at a loss what to do.
I thought to pass it back to the user to solve the situation instead of simply
ignoring the users earlier rename.
Silently renaming sounded a bit presumptuous to me, even though I don't care
that much either way.
Do you think silently renaming is better than yielding an error?
> Also, I think it would be good to have
> ALTER TRIGGER .. ON ONLY parent RENAME TO ..
> to avoid recursing to children. This seems mostly pointless, but since
> we've allowed changing the name of the trigger in children thus far,
> then we've implicitly made it supported to have triggers that are named
> differently. (And it's not entirely academic, since the trigger name
> determines firing order.)
If it would be entirely academic, I wouldn't have noticed the whole thing in
the first place.
The on only variant sounds like a good idea to me. Even though hardly worth any
efford, it seems simple enough. I will work on that.
> Alternatively to this last point, we could decide to disallow renaming
> of triggers on children (i.e. if trigger has tgparentid set, then
> renaming is disallowed). I don't have a problem with that, but it would
> have to be an explicit decision to take.
I rejected that idea, because I was unsure what to do with migrations. If we
would be discussing this a few years back, this would have been likely my vote,
but I don't see it happening now.
Regards
Arne
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index 7383d5994e..14e3edcc5c 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -1348,12 +1348,7 @@ get_trigger_oid(Oid relid, const char *trigname, bool missing_ok)
return oid;
}
-/*
- * Perform permissions and integrity checks before acquiring a relation lock.
- */
-static void
-RangeVarCallbackForRenameTrigger(const RangeVar *rv, Oid relid, Oid oldrelid,
- void *arg)
+static void callbackForRenameTrigger(char* relname, Oid relid)
{
HeapTuple tuple;
Form_pg_class form;
@@ -1370,25 +1365,36 @@ RangeVarCallbackForRenameTrigger(const RangeVar *rv, Oid relid, Oid oldrelid,
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("\"%s\" is not a table, view, or foreign table",
- rv->relname)));
+ relname)));
/* you must own the table to rename one of its triggers */
if (!pg_class_ownercheck(relid, GetUserId()))
- aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relid)), rv->relname);
+ aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relid)), relname);
if (!allowSystemTableMods && IsSystemClass(relid, form))
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied: \"%s\" is a system catalog",
- rv->relname)));
+ relname)));
ReleaseSysCache(tuple);
}
/*
- * renametrig - changes the name of a trigger on a relation
+ * Perform permissions and integrity checks before acquiring a relation lock.
+ */
+static void
+RangeVarCallbackForRenameTrigger(const RangeVar *rv, Oid relid, Oid oldrelid,
+ void *arg)
+{
+ callbackForRenameTrigger(rv->relname, relid);
+}
+
+/*
+ * renameonlytrig - changes the name of a trigger on a relation
*
* trigger name is changed in trigger catalog.
* No record of the previous name is kept.
+ * This function assumes that the row is already locked
*
* get proper relrelation from relation catalog (if not arg)
* scan trigger catalog
@@ -1398,41 +1404,26 @@ RangeVarCallbackForRenameTrigger(const RangeVar *rv, Oid relid, Oid oldrelid,
* update row in catalog
*/
ObjectAddress
-renametrig(RenameStmt *stmt)
+renameonlytrig(RenameStmt *stmt, Relation tgrel, Oid relid, Oid tgparent)
{
Oid tgoid;
Relation targetrel;
- Relation tgrel;
HeapTuple tuple;
SysScanDesc tgscan;
ScanKeyData key[2];
- Oid relid;
ObjectAddress address;
- /*
- * Look up name, check permissions, and acquire lock (which we will NOT
- * release until end of transaction).
- */
- relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
- 0,
- RangeVarCallbackForRenameTrigger,
- NULL);
/* Have lock already, so just need to build relcache entry. */
targetrel = relation_open(relid, NoLock);
+
/*
* 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 = table_open(TriggerRelationId, RowExclusiveLock);
-
- /*
* First pass -- look for name conflict
*/
ScanKeyInit(&key[0],
@@ -1463,6 +1454,7 @@ renametrig(RenameStmt *stmt)
Anum_pg_trigger_tgname,
BTEqualStrategyNumber, F_NAMEEQ,
PointerGetDatum(stmt->subname));
+
tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
NULL, 2, key);
if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
@@ -1475,7 +1467,12 @@ renametrig(RenameStmt *stmt)
tuple = heap_copytuple(tuple); /* need a modifiable copy */
trigform = (Form_pg_trigger) GETSTRUCT(tuple);
tgoid = trigform->oid;
-
+ if (tgparent != 0 && tgparent != trigform->tgparentid) {
+ ereport(ERROR,
+ (errcode(ERRCODE_UNDEFINED_OBJECT),
+ errmsg("trigger \"%s\" for table \"%s\" is not dependent on the trigger on \"%s\"",
+ stmt->subname, RelationGetRelationName(targetrel), stmt->relation->relname)));
+ }
namestrcpy(&trigform->tgname,
stmt->newname);
@@ -1513,6 +1510,74 @@ renametrig(RenameStmt *stmt)
return address;
}
+/*
+ * renametrig - changes the name of a trigger on a possibly partitioned relation recurisvely
+ *
+ * alter name of parent trigger using renameonlytrig
+ * recursive over children and change their names in the same manner
+ *
+ */
+ObjectAddress
+renametrigHelper (RenameStmt *stmt, Oid tgoid, Oid relid)
+{
+
+ Relation tgrel;
+ Oid newtgoid;
+ ObjectAddress tgaddress;
+ /*
+ * NOTE that this is cool only because we have AccessExclusiveLock on the
+ * relation, so the trigger set won't be changing underneath us.
+ */
+ tgrel = table_open(TriggerRelationId, RowExclusiveLock);
+
+ /*
+ * The last call of renametrig or renametrigHelper already locked this relation.
+ */
+ tgaddress = renameonlytrig(stmt, tgrel, relid, tgoid);
+ newtgoid = tgaddress.objectId;
+
+ /*
+ * In case we have a partioned table, we traverse them and rename every dependend
+ * trigger of the same name or error out, if it doesn't exist.
+ */
+ if (stmt->relation->inh && has_subclass(relid))
+ {
+ ListCell *child;
+ List *children;
+
+ /* Make sure it stays a child. */
+ children = find_inheritance_children(relid, AccessExclusiveLock, false);
+
+ /*
+ * find_inheritance_children doesn't work recursively.
+ * we check every layer individually to ensure that the trigger
+ * of the child is matching in case it's a partitioned table itself.
+ */
+ foreach(child, children)
+ {
+ Oid childrelid = lfirst_oid(child);
+
+ if (childrelid == relid)
+ continue;
+ renametrigHelper(stmt, newtgoid, childrelid);
+ }
+ }
+ return tgaddress;
+}
+
+ObjectAddress
+renametrig(RenameStmt *stmt)
+{
+ /*
+ * Look up name, check permissions, and acquire lock (which we will NOT
+ * release until end of transaction).
+ */
+ return renametrigHelper(stmt, 0,
+ RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
+ 0,
+ RangeVarCallbackForRenameTrigger,
+ NULL));
+}
/*
* EnableDisableTrigger()
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 7ff36bc842..84e1747402 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -8851,7 +8851,7 @@ RenameStmt: ALTER AGGREGATE aggregate_with_argtypes RENAME TO name
n->missing_ok = false;
$$ = (Node *)n;
}
- | ALTER TRIGGER name ON qualified_name RENAME TO name
+ | ALTER TRIGGER name ON relation_expr RENAME TO name
{
RenameStmt *n = makeNode(RenameStmt);
n->renameType = OBJECT_TRIGGER;
diff --git a/src/include/commands/trigger.h b/src/include/commands/trigger.h
index 9e557cfbce..8dac23d980 100644
--- a/src/include/commands/trigger.h
+++ b/src/include/commands/trigger.h
@@ -158,6 +158,10 @@ extern ObjectAddress CreateTrigger(CreateTrigStmt *stmt, const char *queryString
extern void RemoveTriggerById(Oid trigOid);
extern Oid get_trigger_oid(Oid relid, const char *name, bool missing_ok);
+extern ObjectAddress renameonlytrig(RenameStmt *stmt, Relation tgrel, Oid relid, Oid tgparent);
+
+extern ObjectAddress renametrigHelper(RenameStmt *stmt, Oid tgoid, Oid relid);
+
extern ObjectAddress renametrig(RenameStmt *stmt);
extern void EnableDisableTrigger(Relation rel, const char *tgname,
