Don't clone internal triggers to partitions

Trigger cloning to partitions was supposed to occur for user-visible
triggers only, but during development the protection that prevented it
from occurring to internal triggers was lost.  Reinstate it, as well as
add a test case to ensure internal triggers (in the tested case,
triggers implementing a deferred unique constraint) are not cloned.
Without the code fix, the partitions in the test end up with different
numbers of triggers, which is clearly wrong ...

Bug in 86f575948c.

Discussion: https://postgr.es/m/20180403214903.ozfagwjcpk337uw7@alvherre.pgsql

src/backend/commands/tablecmds.c

@@ -14336,6 +14336,10 @@ CloneRowTriggersToPartition(Relation parent, Relation partition)
 		if (!TRIGGER_FOR_ROW(trigForm->tgtype))
 			continue;
 
+		/* We don't clone internal triggers, either */
+		if (trigForm->tgisinternal)
+			continue;
+
 		/*
 		 * Complain if we find an unexpected trigger type.
 		 */

src/test/regress/expected/triggers.out

@@ -2234,6 +2234,29 @@ NOTICE:  trigger parted_trigger on parted_trigger_3_1 AFTER UPDATE for ROW: (a,b
 NOTICE:  trigger parted_trigger on parted_trigger_3_2 AFTER UPDATE for ROW: (a,b)=(2003,eeeeb)
 drop table parted_trigger;
 drop function trigger_notice_ab();
+-- Make sure we don't end up with unnecessary copies of triggers, when
+-- cloning them.
+create table trg_clone (a int) partition by range (a);
+create table trg_clone1 partition of trg_clone for values from (0) to (1000);
+alter table trg_clone add constraint uniq unique (a) deferrable;
+create table trg_clone2 partition of trg_clone for values from (1000) to (2000);
+create table trg_clone3 partition of trg_clone for values from (2000) to (3000)
+  partition by range (a);
+create table trg_clone_3_3 partition of trg_clone3 for values from (2000) to (2100);
+select tgrelid::regclass, count(*) from pg_trigger
+  where tgrelid::regclass in ('trg_clone', 'trg_clone1', 'trg_clone2',
+	'trg_clone3', 'trg_clone_3_3')
+  group by tgrelid::regclass order by tgrelid::regclass;
+    tgrelid    | count 
+---------------+-------
+ trg_clone     |     1
+ trg_clone1    |     1
+ trg_clone2    |     1
+ trg_clone3    |     1
+ trg_clone_3_3 |     1
+(5 rows)
+
+drop table trg_clone;
 --
 -- Test the interaction between transition tables and both kinds of
 -- inheritance.  We'll dump the contents of the transition tables in a

src/test/regress/sql/triggers.sql

@@ -1578,6 +1578,21 @@ drop table parted_trigger;
 
 drop function trigger_notice_ab();
 
+-- Make sure we don't end up with unnecessary copies of triggers, when
+-- cloning them.
+create table trg_clone (a int) partition by range (a);
+create table trg_clone1 partition of trg_clone for values from (0) to (1000);
+alter table trg_clone add constraint uniq unique (a) deferrable;
+create table trg_clone2 partition of trg_clone for values from (1000) to (2000);
+create table trg_clone3 partition of trg_clone for values from (2000) to (3000)
+  partition by range (a);
+create table trg_clone_3_3 partition of trg_clone3 for values from (2000) to (2100);
+select tgrelid::regclass, count(*) from pg_trigger
+  where tgrelid::regclass in ('trg_clone', 'trg_clone1', 'trg_clone2',
+	'trg_clone3', 'trg_clone_3_3')
+  group by tgrelid::regclass order by tgrelid::regclass;
+drop table trg_clone;
+
 --
 -- Test the interaction between transition tables and both kinds of
 -- inheritance.  We'll dump the contents of the transition tables in a