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Enable BEFORE row-level triggers for partitioned tables
... with the limitation that the tuple must remain in the same partition. Reviewed-by: Ashutosh Bapat Discussion: https://postgr.es/m/20200227165158.GA2071@alvherre.pgsql
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8 files changed

+161
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lines changed

‎doc/src/sgml/ref/create_trigger.sgml

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -526,7 +526,7 @@ UPDATE OF <replaceable>column_name1</replaceable> [, <replaceable>column_name2</
526526
Creating a row-level trigger on a partitioned table will cause identical
527527
triggers to be created in all its existing partitions; and any partitions
528528
created or attached later will contain an identical trigger, too.
529-
Triggers on partitioned tables may only be <literal>AFTER</literal>.
529+
Triggers on partitioned tables may not be <literal>INSTEAD OF</literal>.
530530
</para>
531531

532532
<para>

‎doc/src/sgml/trigger.sgml

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -116,8 +116,7 @@
116116
operated on, while row-level <literal>AFTER</literal> triggers fire at the end of
117117
the statement (but before any statement-level <literal>AFTER</literal> triggers).
118118
These types of triggers may only be defined on tables and
119-
foreign tables, not views; <literal>BEFORE</literal> row-level triggers may not
120-
be defined on partitioned tables.
119+
foreign tables, not views.
121120
<literal>INSTEAD OF</literal> triggers may only be
122121
defined on views, and only at row level; they fire immediately as each
123122
row in the view is identified as needing to be operated on.

‎src/backend/commands/tablecmds.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16546,7 +16546,8 @@ CloneRowTriggersToPartition(Relation parent, Relation partition)
1654616546
/*
1654716547
* Complain if we find an unexpected trigger type.
1654816548
*/
16549-
if (!TRIGGER_FOR_AFTER(trigForm->tgtype))
16549+
if (!TRIGGER_FOR_BEFORE(trigForm->tgtype) &&
16550+
!TRIGGER_FOR_AFTER(trigForm->tgtype))
1655016551
elog(ERROR, "unexpected trigger \"%s\" found",
1655116552
NameStr(trigForm->tgname));
1655216553

‎src/backend/commands/trigger.c

Lines changed: 28 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -221,18 +221,6 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
221221
*/
222222
if (stmt->row)
223223
{
224-
/*
225-
* BEFORE triggers FOR EACH ROW are forbidden, because they would
226-
* allow the user to direct the row to another partition, which
227-
* isn't implemented in the executor.
228-
*/
229-
if (stmt->timing != TRIGGER_TYPE_AFTER)
230-
ereport(ERROR,
231-
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
232-
errmsg("\"%s\" is a partitioned table",
233-
RelationGetRelationName(rel)),
234-
errdetail("Partitioned tables cannot have BEFORE / FOR EACH ROW triggers.")));
235-
236224
/*
237225
* Disallow use of transition tables.
238226
*
@@ -1658,6 +1646,7 @@ RelationBuildTriggers(Relation relation)
16581646
build->tgtype = pg_trigger->tgtype;
16591647
build->tgenabled = pg_trigger->tgenabled;
16601648
build->tgisinternal = pg_trigger->tgisinternal;
1649+
build->tgisclone = OidIsValid(pg_trigger->tgparentid);
16611650
build->tgconstrrelid = pg_trigger->tgconstrrelid;
16621651
build->tgconstrindid = pg_trigger->tgconstrindid;
16631652
build->tgconstraint = pg_trigger->tgconstraint;
@@ -1961,6 +1950,8 @@ equalTriggerDescs(TriggerDesc *trigdesc1, TriggerDesc *trigdesc2)
19611950
return false;
19621951
if (trig1->tgisinternal != trig2->tgisinternal)
19631952
return false;
1953+
if (trig1->tgisclone != trig2->tgisclone)
1954+
return false;
19641955
if (trig1->tgconstrrelid != trig2->tgconstrrelid)
19651956
return false;
19661957
if (trig1->tgconstrindid != trig2->tgconstrindid)
@@ -2247,6 +2238,21 @@ ExecBRInsertTriggers(EState *estate, ResultRelInfo *relinfo,
22472238
{
22482239
ExecForceStoreHeapTuple(newtuple, slot, false);
22492240

2241+
/*
2242+
* After a tuple in a partition goes through a trigger, the user
2243+
* could have changed the partition key enough that the tuple
2244+
* no longer fits the partition. Verify that.
2245+
*/
2246+
if (trigger->tgisclone &&
2247+
!ExecPartitionCheck(relinfo, slot, estate, false))
2248+
ereport(ERROR,
2249+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2250+
errmsg("moving row to another partition during a BEFORE FOR EACH ROW trigger is not supported"),
2251+
errdetail("Before executing trigger \"%s\", the row was to be in partition \"%s.%s\".",
2252+
trigger->tgname,
2253+
get_namespace_name(RelationGetNamespace(relinfo->ri_RelationDesc)),
2254+
RelationGetRelationName(relinfo->ri_RelationDesc))));
2255+
22502256
if (should_free)
22512257
heap_freetuple(oldtuple);
22522258

@@ -2741,6 +2747,16 @@ ExecBRUpdateTriggers(EState *estate, EPQState *epqstate,
27412747
{
27422748
ExecForceStoreHeapTuple(newtuple, newslot, false);
27432749

2750+
if (trigger->tgisclone &&
2751+
!ExecPartitionCheck(relinfo, newslot, estate, false))
2752+
ereport(ERROR,
2753+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2754+
errmsg("moving row to another partition during a BEFORE trigger is not supported"),
2755+
errdetail("Before executing trigger \"%s\", the row was to be in partition \"%s.%s\".",
2756+
trigger->tgname,
2757+
get_namespace_name(RelationGetNamespace(relinfo->ri_RelationDesc)),
2758+
RelationGetRelationName(relinfo->ri_RelationDesc))));
2759+
27442760
/*
27452761
* If the tuple returned by the trigger / being stored, is the old
27462762
* row version, and the heap tuple passed to the trigger was

‎src/backend/partitioning/partdesc.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -307,7 +307,7 @@ CreatePartitionDirectory(MemoryContext mcxt)
307307
*
308308
* The purpose of this function is to ensure that we get the same
309309
* PartitionDesc for each relation every time we look it up. In the
310-
* face of current DDL, different PartitionDescs may be constructed with
310+
* face of concurrent DDL, different PartitionDescs may be constructed with
311311
* different views of the catalog state, but any single particular OID
312312
* will always get the same PartitionDesc for as long as the same
313313
* PartitionDirectory is used.

‎src/include/utils/reltrigger.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,7 @@ typedef struct Trigger
2929
int16 tgtype;
3030
char tgenabled;
3131
bool tgisinternal;
32+
bool tgisclone;
3233
Oid tgconstrrelid;
3334
Oid tgconstrindid;
3435
Oid tgconstraint;

‎src/test/regress/expected/triggers.out

Lines changed: 74 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1958,10 +1958,6 @@ drop table my_table;
19581958
create table parted_trig (a int) partition by list (a);
19591959
create function trigger_nothing() returns trigger
19601960
language plpgsql as $$ begin end; $$;
1961-
create trigger failed before insert or update or delete on parted_trig
1962-
for each row execute procedure trigger_nothing();
1963-
ERROR: "parted_trig" is a partitioned table
1964-
DETAIL: Partitioned tables cannot have BEFORE / FOR EACH ROW triggers.
19651961
create trigger failed instead of update on parted_trig
19661962
for each row execute procedure trigger_nothing();
19671963
ERROR: "parted_trig" is a table
@@ -2246,6 +2242,80 @@ NOTICE: aasvogel <- woof!
22462242
NOTICE: trigger parted_trig on parted1_irreg AFTER INSERT for ROW: (a,b)=(3,aasvogel)
22472243
NOTICE: trigger parted_trig_odd on parted1_irreg AFTER INSERT for ROW: (a,b)=(3,aasvogel)
22482244
drop table parted_irreg_ancestor;
2245+
-- Before triggers and partitions
2246+
create table parted (a int, b int, c text) partition by list (a);
2247+
create table parted_1 partition of parted for values in (1)
2248+
partition by list (b);
2249+
create table parted_1_1 partition of parted_1 for values in (1);
2250+
create function parted_trigfunc() returns trigger language plpgsql as $$
2251+
begin
2252+
new.a = new.a + 1;
2253+
return new;
2254+
end;
2255+
$$;
2256+
insert into parted values (1, 1, 'uno uno v1'); -- works
2257+
create trigger t before insert or update or delete on parted
2258+
for each row execute function parted_trigfunc();
2259+
insert into parted values (1, 1, 'uno uno v2'); -- fail
2260+
ERROR: moving row to another partition during a BEFORE FOR EACH ROW trigger is not supported
2261+
DETAIL: Before executing trigger "t", the row was to be in partition "public.parted_1_1".
2262+
update parted set c = c || 'v3'; -- fail
2263+
ERROR: moving row to another partition during a BEFORE trigger is not supported
2264+
DETAIL: Before executing trigger "t", the row was to be in partition "public.parted_1_1".
2265+
create or replace function parted_trigfunc() returns trigger language plpgsql as $$
2266+
begin
2267+
new.b = new.b + 1;
2268+
return new;
2269+
end;
2270+
$$;
2271+
insert into parted values (1, 1, 'uno uno v4'); -- fail
2272+
ERROR: moving row to another partition during a BEFORE FOR EACH ROW trigger is not supported
2273+
DETAIL: Before executing trigger "t", the row was to be in partition "public.parted_1_1".
2274+
update parted set c = c || 'v5'; -- fail
2275+
ERROR: moving row to another partition during a BEFORE trigger is not supported
2276+
DETAIL: Before executing trigger "t", the row was to be in partition "public.parted_1_1".
2277+
create or replace function parted_trigfunc() returns trigger language plpgsql as $$
2278+
begin
2279+
new.c = new.c || ' and so';
2280+
return new;
2281+
end;
2282+
$$;
2283+
insert into parted values (1, 1, 'uno uno'); -- works
2284+
update parted set c = c || ' v6'; -- works
2285+
select tableoid::regclass, * from parted;
2286+
tableoid | a | b | c
2287+
------------+---+---+--------------------------
2288+
parted_1_1 | 1 | 1 | uno uno v1 v6 and so
2289+
parted_1_1 | 1 | 1 | uno uno and so v6 and so
2290+
(2 rows)
2291+
2292+
drop table parted;
2293+
create table parted (a int, b int, c text) partition by list ((a + b));
2294+
create or replace function parted_trigfunc() returns trigger language plpgsql as $$
2295+
begin
2296+
new.a = new.a + new.b;
2297+
return new;
2298+
end;
2299+
$$;
2300+
create table parted_1 partition of parted for values in (1, 2);
2301+
create table parted_2 partition of parted for values in (3, 4);
2302+
create trigger t before insert or update on parted
2303+
for each row execute function parted_trigfunc();
2304+
insert into parted values (0, 1, 'zero win');
2305+
insert into parted values (1, 1, 'one fail');
2306+
ERROR: moving row to another partition during a BEFORE FOR EACH ROW trigger is not supported
2307+
DETAIL: Before executing trigger "t", the row was to be in partition "public.parted_1".
2308+
insert into parted values (1, 2, 'two fail');
2309+
ERROR: moving row to another partition during a BEFORE FOR EACH ROW trigger is not supported
2310+
DETAIL: Before executing trigger "t", the row was to be in partition "public.parted_2".
2311+
select * from parted;
2312+
a | b | c
2313+
---+---+----------
2314+
1 | 1 | zero win
2315+
(1 row)
2316+
2317+
drop table parted;
2318+
drop function parted_trigfunc();
22492319
--
22502320
-- Constraint triggers and partitioned tables
22512321
create table parted_constr_ancestor (a int, b text)

‎src/test/regress/sql/triggers.sql

Lines changed: 53 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1348,8 +1348,6 @@ drop table my_table;
13481348
create table parted_trig (a int) partition by list (a);
13491349
create function trigger_nothing() returns trigger
13501350
language plpgsql as $$ begin end; $$;
1351-
create trigger failed before insert or update or delete on parted_trig
1352-
for each row execute procedure trigger_nothing();
13531351
create trigger failed instead of update on parted_trig
13541352
for each row execute procedure trigger_nothing();
13551353
create trigger failed after update on parted_trig
@@ -1561,6 +1559,59 @@ insert into parted1_irreg values ('aardwolf', 2);
15611559
insert into parted_irreg_ancestor values ('aasvogel', 3);
15621560
drop table parted_irreg_ancestor;
15631561

1562+
-- Before triggers and partitions
1563+
create table parted (a int, b int, c text) partition by list (a);
1564+
create table parted_1 partition of parted for values in (1)
1565+
partition by list (b);
1566+
create table parted_1_1 partition of parted_1 for values in (1);
1567+
create function parted_trigfunc() returns trigger language plpgsql as $$
1568+
begin
1569+
new.a = new.a + 1;
1570+
return new;
1571+
end;
1572+
$$;
1573+
insert into parted values (1, 1, 'uno uno v1'); -- works
1574+
create trigger t before insert or update or delete on parted
1575+
for each row execute function parted_trigfunc();
1576+
insert into parted values (1, 1, 'uno uno v2'); -- fail
1577+
update parted set c = c || 'v3'; -- fail
1578+
create or replace function parted_trigfunc() returns trigger language plpgsql as $$
1579+
begin
1580+
new.b = new.b + 1;
1581+
return new;
1582+
end;
1583+
$$;
1584+
insert into parted values (1, 1, 'uno uno v4'); -- fail
1585+
update parted set c = c || 'v5'; -- fail
1586+
create or replace function parted_trigfunc() returns trigger language plpgsql as $$
1587+
begin
1588+
new.c = new.c || ' and so';
1589+
return new;
1590+
end;
1591+
$$;
1592+
insert into parted values (1, 1, 'uno uno'); -- works
1593+
update parted set c = c || ' v6'; -- works
1594+
select tableoid::regclass, * from parted;
1595+
1596+
drop table parted;
1597+
create table parted (a int, b int, c text) partition by list ((a + b));
1598+
create or replace function parted_trigfunc() returns trigger language plpgsql as $$
1599+
begin
1600+
new.a = new.a + new.b;
1601+
return new;
1602+
end;
1603+
$$;
1604+
create table parted_1 partition of parted for values in (1, 2);
1605+
create table parted_2 partition of parted for values in (3, 4);
1606+
create trigger t before insert or update on parted
1607+
for each row execute function parted_trigfunc();
1608+
insert into parted values (0, 1, 'zero win');
1609+
insert into parted values (1, 1, 'one fail');
1610+
insert into parted values (1, 2, 'two fail');
1611+
select * from parted;
1612+
drop table parted;
1613+
drop function parted_trigfunc();
1614+
15641615
--
15651616
-- Constraint triggers and partitioned tables
15661617
create table parted_constr_ancestor (a int, b text)

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