On 2022-Aug-02, Amit Langote wrote:
> Regarding the patch, I agree that storing the recurse flag rather than
> overwriting subtype might be better.
>
> + bool execTimeRecursion; /* set by ATPrepCmd if ATExecCmd must
> + * recurse to children */
>
> Might it be better to call this field simply 'recurse'? I think it's
> clear from the context and the comment above the flag is to be used
> during execution.
Yeah, I guess we can do that and also reword the overall ALTER TABLE
comment about recursion. That's in the attached first patch, which is
intended as backpatchable.
The second patch is just to show how we'd rewrite AT_AddColumn to no
longer use the Recurse separate enum value but instead use the ->recurse
flag. This is pretty straightforward and it's a clear net reduction of
code. We can't backpatch this kind of thing of course, both because of
the ABI break (easily fixed) and because potential destabilization
(scary). We can do similar tihngs for the other AT enum values for
recursion. This isn't complete since there are a few other values in
that enum that we should process in this way too; I don't intend it to
push it just yet.
--
Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/
"XML!" Exclaimed C++. "What are you doing here? You're not a programming
language."
"Tell that to the people who use me," said XML.
https://burningbird.net/the-parable-of-the-languages/
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d22dd44712..70b94bbb39 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -580,7 +580,8 @@ static void ATExecSetRelOptions(Relation rel, List *defList,
AlterTableType operation,
LOCKMODE lockmode);
static void ATExecEnableDisableTrigger(Relation rel, const char *trigname,
- char fires_when, bool skip_system, LOCKMODE lockmode);
+ char fires_when, bool skip_system, bool recurse,
+ LOCKMODE lockmode);
static void ATExecEnableDisableRule(Relation rel, const char *rulename,
char fires_when, LOCKMODE lockmode);
static void ATPrepAddInherit(Relation child_rel);
@@ -4057,9 +4058,7 @@ AlterTableLookupRelation(AlterTableStmt *stmt, LOCKMODE lockmode)
* be done in this phase. Generally, this phase acquires table locks,
* checks permissions and relkind, and recurses to find child tables.
*
- * ATRewriteCatalogs performs phase 2 for each affected table. (Note that
- * phases 2 and 3 normally do no explicit recursion, since phase 1 already
- * did it --- although some subcommands have to recurse in phase 2 instead.)
+ * ATRewriteCatalogs performs phase 2 for each affected table.
* Certain subcommands need to be performed before others to avoid
* unnecessary conflicts; for example, DROP COLUMN should come before
* ADD COLUMN. Therefore phase 1 divides the subcommands into multiple
@@ -4067,6 +4066,12 @@ AlterTableLookupRelation(AlterTableStmt *stmt, LOCKMODE lockmode)
*
* ATRewriteTables performs phase 3 for those tables that need it.
*
+ * For most subcommand types, phases 2 and 3 do no explicit recursion,
+ * since phase 1 already does it. However, for certain subcommand types
+ * it is only possible to determine how to recurse at phase 2 time; for
+ * those cases, phase 1 sets the cmd->recurse flag (or, in some older coding,
+ * changes the command subtype of a "Recurse" variant XXX to be cleaned up.)
+ *
* Thanks to the magic of MVCC, an error anywhere along the way rolls back
* the whole operation; we don't have to do anything special to clean up.
*
@@ -4487,10 +4492,10 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
errhint("Use ALTER TABLE ... DETACH PARTITION ... FINALIZE to complete the pending detach operation."));
/*
- * Copy the original subcommand for each table. This avoids conflicts
- * when different child tables need to make different parse
- * transformations (for example, the same column may have different column
- * numbers in different children).
+ * Copy the original subcommand for each table, so we can scribble on it.
+ * This avoids conflicts when different child tables need to make
+ * different parse transformations (for example, the same column may have
+ * different column numbers in different children).
*/
cmd = copyObject(cmd);
@@ -4777,8 +4782,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
case AT_DisableTrigAll:
case AT_DisableTrigUser:
ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_FOREIGN_TABLE);
- if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
- ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
+ /* Set up recursion for phase 2; no other prep needed */
+ if (recurse)
+ cmd->recurse = true;
pass = AT_PASS_MISC;
break;
case AT_EnableRule: /* ENABLE/DISABLE RULE variants */
@@ -5119,35 +5125,51 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
break;
case AT_EnableTrig: /* ENABLE TRIGGER name */
ATExecEnableDisableTrigger(rel, cmd->name,
- TRIGGER_FIRES_ON_ORIGIN, false, lockmode);
+ TRIGGER_FIRES_ON_ORIGIN, false,
+ cmd->recurse,
+ lockmode);
break;
case AT_EnableAlwaysTrig: /* ENABLE ALWAYS TRIGGER name */
ATExecEnableDisableTrigger(rel, cmd->name,
- TRIGGER_FIRES_ALWAYS, false, lockmode);
+ TRIGGER_FIRES_ALWAYS, false,
+ cmd->recurse,
+ lockmode);
break;
case AT_EnableReplicaTrig: /* ENABLE REPLICA TRIGGER name */
ATExecEnableDisableTrigger(rel, cmd->name,
- TRIGGER_FIRES_ON_REPLICA, false, lockmode);
+ TRIGGER_FIRES_ON_REPLICA, false,
+ cmd->recurse,
+ lockmode);
break;
case AT_DisableTrig: /* DISABLE TRIGGER name */
ATExecEnableDisableTrigger(rel, cmd->name,
- TRIGGER_DISABLED, false, lockmode);
+ TRIGGER_DISABLED, false,
+ cmd->recurse,
+ lockmode);
break;
case AT_EnableTrigAll: /* ENABLE TRIGGER ALL */
ATExecEnableDisableTrigger(rel, NULL,
- TRIGGER_FIRES_ON_ORIGIN, false, lockmode);
+ TRIGGER_FIRES_ON_ORIGIN, false,
+ cmd->recurse,
+ lockmode);
break;
case AT_DisableTrigAll: /* DISABLE TRIGGER ALL */
ATExecEnableDisableTrigger(rel, NULL,
- TRIGGER_DISABLED, false, lockmode);
+ TRIGGER_DISABLED, false,
+ cmd->recurse,
+ lockmode);
break;
case AT_EnableTrigUser: /* ENABLE TRIGGER USER */
ATExecEnableDisableTrigger(rel, NULL,
- TRIGGER_FIRES_ON_ORIGIN, true, lockmode);
+ TRIGGER_FIRES_ON_ORIGIN, true,
+ cmd->recurse,
+ lockmode);
break;
case AT_DisableTrigUser: /* DISABLE TRIGGER USER */
ATExecEnableDisableTrigger(rel, NULL,
- TRIGGER_DISABLED, true, lockmode);
+ TRIGGER_DISABLED, true,
+ cmd->recurse,
+ lockmode);
break;
case AT_EnableRule: /* ENABLE RULE name */
@@ -14660,9 +14682,11 @@ index_copy_data(Relation rel, RelFileLocator newrlocator)
*/
static void
ATExecEnableDisableTrigger(Relation rel, const char *trigname,
- char fires_when, bool skip_system, LOCKMODE lockmode)
+ char fires_when, bool skip_system, bool recurse,
+ LOCKMODE lockmode)
{
- EnableDisableTrigger(rel, trigname, fires_when, skip_system, lockmode);
+ EnableDisableTrigger(rel, trigname, fires_when, skip_system, recurse,
+ lockmode);
}
/*
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index b8db53b66d..b0416ada94 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -1752,6 +1752,7 @@ renametrig_partition(Relation tgrel, Oid partitionId, Oid parentTriggerOid,
* enablement/disablement, this also defines when the trigger
* should be fired in session replication roles.
* skip_system: if true, skip "system" triggers (constraint triggers)
+ * recurse: if true, recurse to partitions
*
* Caller should have checked permissions for the table; here we also
* enforce that superuser privilege is required to alter the state of
@@ -1759,7 +1760,8 @@ renametrig_partition(Relation tgrel, Oid partitionId, Oid parentTriggerOid,
*/
void
EnableDisableTrigger(Relation rel, const char *tgname,
- char fires_when, bool skip_system, LOCKMODE lockmode)
+ char fires_when, bool skip_system, bool recurse,
+ LOCKMODE lockmode)
{
Relation tgrel;
int nkeys;
@@ -1825,6 +1827,34 @@ EnableDisableTrigger(Relation rel, const char *tgname,
changed = true;
}
+ /*
+ * When altering FOR EACH ROW triggers on a partitioned table, do
+ * the same on the partitions as well, unless ONLY is specified.
+ *
+ * Note that we recurse even if we didn't change the trigger above,
+ * because the partitions' copy of the trigger may have a different
+ * value of tgenabled than the parent's trigger and thus might need
+ * to be changed.
+ */
+ if (recurse &&
+ rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
+ (TRIGGER_FOR_ROW(oldtrig->tgtype)))
+ {
+ PartitionDesc partdesc = RelationGetPartitionDesc(rel, true);
+ int i;
+
+ for (i = 0; i < partdesc->nparts; i++)
+ {
+ Relation part;
+
+ part = relation_open(partdesc->oids[i], lockmode);
+ EnableDisableTrigger(part, NameStr(oldtrig->tgname),
+ fires_when, skip_system, recurse,
+ lockmode);
+ table_close(part, NoLock); /* keep lock till commit */
+ }
+ }
+
InvokeObjectPostAlterHook(TriggerRelationId,
oldtrig->oid, 0);
}
diff --git a/src/include/commands/trigger.h b/src/include/commands/trigger.h
index 194e8d5bc1..b7b6bd6008 100644
--- a/src/include/commands/trigger.h
+++ b/src/include/commands/trigger.h
@@ -171,7 +171,8 @@ extern Oid get_trigger_oid(Oid relid, const char *name, bool missing_ok);
extern ObjectAddress renametrig(RenameStmt *stmt);
extern void EnableDisableTrigger(Relation rel, const char *tgname,
- char fires_when, bool skip_system, LOCKMODE lockmode);
+ char fires_when, bool skip_system, bool recurse,
+ LOCKMODE lockmode);
extern void RelationBuildTriggers(Relation relation);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 98fe1abaa2..b376031856 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2328,6 +2328,7 @@ typedef struct AlterTableCmd /* one subcommand of an ALTER TABLE */
* constraint, or parent table */
DropBehavior behavior; /* RESTRICT or CASCADE for DROP cases */
bool missing_ok; /* skip error if missing? */
+ bool recurse; /* exec-time recursion */
} AlterTableCmd;
diff --git a/src/test/regress/expected/triggers.out b/src/test/regress/expected/triggers.out
index 89a34ffbb2..f131405bc7 100644
--- a/src/test/regress/expected/triggers.out
+++ b/src/test/regress/expected/triggers.out
@@ -2681,24 +2681,42 @@ create table parent (a int) partition by list (a);
create table child1 partition of parent for values in (1);
create trigger tg after insert on parent
for each row execute procedure trig_nothing();
+create trigger tg_stmt after insert on parent
+ for statement execute procedure trig_nothing();
select tgrelid::regclass, tgname, tgenabled from pg_trigger
where tgrelid in ('parent'::regclass, 'child1'::regclass)
order by tgrelid::regclass::text;
- tgrelid | tgname | tgenabled
----------+--------+-----------
- child1 | tg | O
- parent | tg | O
-(2 rows)
+ tgrelid | tgname | tgenabled
+---------+---------+-----------
+ child1 | tg | O
+ parent | tg | O
+ parent | tg_stmt | O
+(3 rows)
-alter table only parent enable always trigger tg;
+alter table only parent enable always trigger tg; -- no recursion because ONLY
+alter table parent enable always trigger tg_stmt; -- no recursion because statement trigger
select tgrelid::regclass, tgname, tgenabled from pg_trigger
where tgrelid in ('parent'::regclass, 'child1'::regclass)
order by tgrelid::regclass::text;
- tgrelid | tgname | tgenabled
----------+--------+-----------
- child1 | tg | O
- parent | tg | A
-(2 rows)
+ tgrelid | tgname | tgenabled
+---------+---------+-----------
+ child1 | tg | O
+ parent | tg | A
+ parent | tg_stmt | A
+(3 rows)
+
+-- The following is a no-op for the parent trigger but not so
+-- for the child trigger, so recursion should be applied.
+alter table parent enable always trigger tg;
+select tgrelid::regclass, tgname, tgenabled from pg_trigger
+ where tgrelid in ('parent'::regclass, 'child1'::regclass)
+ order by tgrelid::regclass::text;
+ tgrelid | tgname | tgenabled
+---------+---------+-----------
+ child1 | tg | A
+ parent | tg | A
+ parent | tg_stmt | A
+(3 rows)
drop table parent, child1;
-- Verify that firing state propagates correctly on creation, too
diff --git a/src/test/regress/sql/triggers.sql b/src/test/regress/sql/triggers.sql
index 83cd00f54f..cb6fc4a90e 100644
--- a/src/test/regress/sql/triggers.sql
+++ b/src/test/regress/sql/triggers.sql
@@ -1865,10 +1865,19 @@ create table parent (a int) partition by list (a);
create table child1 partition of parent for values in (1);
create trigger tg after insert on parent
for each row execute procedure trig_nothing();
+create trigger tg_stmt after insert on parent
+ for statement execute procedure trig_nothing();
select tgrelid::regclass, tgname, tgenabled from pg_trigger
where tgrelid in ('parent'::regclass, 'child1'::regclass)
order by tgrelid::regclass::text;
-alter table only parent enable always trigger tg;
+alter table only parent enable always trigger tg; -- no recursion because ONLY
+alter table parent enable always trigger tg_stmt; -- no recursion because statement trigger
+select tgrelid::regclass, tgname, tgenabled from pg_trigger
+ where tgrelid in ('parent'::regclass, 'child1'::regclass)
+ order by tgrelid::regclass::text;
+-- The following is a no-op for the parent trigger but not so
+-- for the child trigger, so recursion should be applied.
+alter table parent enable always trigger tg;
select tgrelid::regclass, tgname, tgenabled from pg_trigger
where tgrelid in ('parent'::regclass, 'child1'::regclass)
order by tgrelid::regclass::text;
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 70b94bbb39..ec614a8f14 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4929,12 +4929,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
case AT_AddColumn: /* ADD COLUMN */
case AT_AddColumnToView: /* add column via CREATE OR REPLACE VIEW */
address = ATExecAddColumn(wqueue, tab, rel, &cmd,
- false, false,
- lockmode, cur_pass, context);
- break;
- case AT_AddColumnRecurse:
- address = ATExecAddColumn(wqueue, tab, rel, &cmd,
- true, false,
+ cmd->recurse, false,
lockmode, cur_pass, context);
break;
case AT_ColumnDefault: /* ALTER COLUMN DEFAULT */
@@ -6109,7 +6104,6 @@ alter_table_type_to_string(AlterTableType cmdtype)
switch (cmdtype)
{
case AT_AddColumn:
- case AT_AddColumnRecurse:
case AT_AddColumnToView:
return "ADD COLUMN";
case AT_ColumnDefault:
@@ -6670,7 +6664,7 @@ ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
ATTypedTableRecursion(wqueue, rel, cmd, lockmode, context);
if (recurse && !is_view)
- cmd->subtype = AT_AddColumnRecurse;
+ cmd->recurse = true;
}
/*
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index b57253463b..b964419f8b 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -3355,7 +3355,6 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
switch (cmd->subtype)
{
case AT_AddColumn:
- case AT_AddColumnRecurse:
{
ColumnDef *def = castNode(ColumnDef, cmd->def);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index b376031856..7e0688cdbd 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2236,7 +2236,6 @@ typedef struct AlterTableStmt
typedef enum AlterTableType
{
AT_AddColumn, /* add column */
- AT_AddColumnRecurse, /* internal to commands/tablecmds.c */
AT_AddColumnToView, /* implicitly via CREATE OR REPLACE VIEW */
AT_ColumnDefault, /* alter column default */
AT_CookedColumnDefault, /* add a pre-cooked column default */
diff --git a/src/test/modules/test_ddl_deparse/test_ddl_deparse.c b/src/test/modules/test_ddl_deparse/test_ddl_deparse.c
index bdbe05ceeb..0617a09d2b 100644
--- a/src/test/modules/test_ddl_deparse/test_ddl_deparse.c
+++ b/src/test/modules/test_ddl_deparse/test_ddl_deparse.c
@@ -114,9 +114,6 @@ get_altertable_subcmdinfo(PG_FUNCTION_ARGS)
case AT_AddColumn:
strtype = "ADD COLUMN";
break;
- case AT_AddColumnRecurse:
- strtype = "ADD COLUMN (and recurse)";
- break;
case AT_AddColumnToView:
strtype = "ADD COLUMN TO VIEW";
break;
@@ -326,7 +323,10 @@ get_altertable_subcmdinfo(PG_FUNCTION_ARGS)
break;
}
- values[0] = CStringGetTextDatum(strtype);
+ if (subcmd->recurse)
+ values[0] = CStringGetTextDatum(psprintf("%s (and recurse)", strtype));
+ else
+ values[0] = CStringGetTextDatum(strtype);
if (OidIsValid(sub->address.objectId))
{
char *objdesc;
