Fix catalog insertion order for ATTACH PARTITION

Commit 2fbdf1b38b changed the order in which we inserted catalog rows
when creating partitions, so that we could remove an unsightly hack
required for untimely relcache invalidations.  However, that commit only
changed the ordering for CREATE TABLE PARTITION OF, and left ALTER TABLE
ATTACH PARTITION unchanged, so the latter can be affected when catalog
invalidations occur, for instance when the partition key involves an SQL
function.

Reported-by: Rajkumar Raghuwanshi
Author: Amit Langote
Reviewed-by: Michaël Paquier
Discussion: https://postgr.es/m/CAKcux6=nTz9KSfTr_6Z2mpzLJ_09JN-rK6=dWic6gGyTSWueyQ@mail.gmail.com

src/backend/commands/tablecmds.c

@@ -14247,9 +14247,6 @@ ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd)
 						trigger_name, RelationGetRelationName(attachrel)),
 				 errdetail("ROW triggers with transition tables are not supported on partitions")));
 
-	/* OK to create inheritance.  Rest of the checks performed there */
-	CreateInheritance(attachrel, rel);
-
 	/*
 	 * Check that the new partition's bound is valid and does not overlap any
 	 * of existing partitions of the parent - note that it does not return on
@@ -14258,6 +14255,9 @@ ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd)
 	check_new_partition_bound(RelationGetRelationName(attachrel), rel,
 							  cmd->bound);
 
+	/* OK to create inheritance.  Rest of the checks performed there */
+	CreateInheritance(attachrel, rel);
+
 	/* Update the pg_class entry. */
 	StorePartitionBound(attachrel, rel, cmd->bound);
 

src/test/regress/expected/alter_table.out

@@ -3960,3 +3960,18 @@ ERROR:  cannot attach a temporary relation as partition of permanent relation "p
 alter table temp_part_parent attach partition temp_part_child default; -- ok
 drop table perm_part_parent cascade;
 drop table temp_part_parent cascade;
+-- test case where the partitioning operator is a SQL function whose
+-- evaluation results in the table's relcache being rebuilt partway through
+-- the execution of an ATTACH PARTITION command
+create function at_test_sql_partop (int4, int4) returns int language sql
+as $$ select case when $1 = $2 then 0 when $1 > $2 then 1 else -1 end; $$;
+create operator class at_test_sql_partop for type int4 using btree as
+    operator 1 < (int4, int4), operator 2 <= (int4, int4),
+    operator 3 = (int4, int4), operator 4 >= (int4, int4),
+    operator 5 > (int4, int4), function 1 at_test_sql_partop(int4, int4);
+create table at_test_sql_partop (a int) partition by range (a at_test_sql_partop);
+create table at_test_sql_partop_1 (a int);
+alter table at_test_sql_partop attach partition at_test_sql_partop_1 for values from (0) to (10);
+drop table at_test_sql_partop;
+drop operator class at_test_sql_partop using btree;
+drop function at_test_sql_partop;

src/test/regress/sql/alter_table.sql

@@ -2618,3 +2618,19 @@ alter table perm_part_parent attach partition temp_part_child default; -- error
 alter table temp_part_parent attach partition temp_part_child default; -- ok
 drop table perm_part_parent cascade;
 drop table temp_part_parent cascade;
+
+-- test case where the partitioning operator is a SQL function whose
+-- evaluation results in the table's relcache being rebuilt partway through
+-- the execution of an ATTACH PARTITION command
+create function at_test_sql_partop (int4, int4) returns int language sql
+as $$ select case when $1 = $2 then 0 when $1 > $2 then 1 else -1 end; $$;
+create operator class at_test_sql_partop for type int4 using btree as
+    operator 1 < (int4, int4), operator 2 <= (int4, int4),
+    operator 3 = (int4, int4), operator 4 >= (int4, int4),
+    operator 5 > (int4, int4), function 1 at_test_sql_partop(int4, int4);
+create table at_test_sql_partop (a int) partition by range (a at_test_sql_partop);
+create table at_test_sql_partop_1 (a int);
+alter table at_test_sql_partop attach partition at_test_sql_partop_1 for values from (0) to (10);
+drop table at_test_sql_partop;
+drop operator class at_test_sql_partop using btree;
+drop function at_test_sql_partop;