From c3712a48c14ca4b2182aaf6629923496b4fe9577 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Thu, 27 Aug 2020 13:50:15 -0400
Subject: [PATCH v2] Raise error on concurrent drop of partitioned index

We were already raising an error for DROP INDEX CONCURRENTLY on a
partitioned table, albeit a different and confusing one:
  ERROR:  DROP INDEX CONCURRENTLY must be first action in transaction

Change that to throw a more comprehensible error:
  ERROR:  cannot drop partitioned index \"%s\" concurrently

Reported-by: Jan Mussler <jan.mussler@zalando.de>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/16594-d2956ca909585067@postgresql.org
---
 src/backend/commands/tablecmds.c       | 11 +++++++++++
 src/test/regress/expected/indexing.out |  2 ++
 src/test/regress/sql/indexing.sql      |  1 +
 3 files changed, 14 insertions(+)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d2b15a3387..3e57c7f9e1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -1373,6 +1373,17 @@ RemoveRelations(DropStmt *drop)
 			flags |= PERFORM_DELETION_CONCURRENTLY;
 		}
 
+		/*
+		 * Concurrent index drop cannot be used with partitioned indexes,
+		 * either.
+		 */
+		if ((flags & PERFORM_DELETION_CONCURRENTLY) != 0 &&
+			get_rel_relkind(relOid) == RELKIND_PARTITIONED_INDEX)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("cannot drop partitioned index \"%s\" concurrently",
+							rel->relname)));
+
 		/* OK, we're ready to delete this one */
 		obj.classId = RelationRelationId;
 		obj.objectId = relOid;
diff --git a/src/test/regress/expected/indexing.out b/src/test/regress/expected/indexing.out
index f78865ef81..6086d51bd8 100644
--- a/src/test/regress/expected/indexing.out
+++ b/src/test/regress/expected/indexing.out
@@ -174,6 +174,8 @@ create table idxpart1 partition of idxpart for values from (0) to (10);
 drop index idxpart1_a_idx;	-- no way
 ERROR:  cannot drop index idxpart1_a_idx because index idxpart_a_idx requires it
 HINT:  You can drop index idxpart_a_idx instead.
+drop index concurrently idxpart_a_idx;	-- unsupported
+ERROR:  cannot drop partitioned index "idxpart_a_idx" concurrently
 drop index idxpart_a_idx;	-- both indexes go away
 select relname, relkind from pg_class
   where relname like 'idxpart%' order by relname;
diff --git a/src/test/regress/sql/indexing.sql b/src/test/regress/sql/indexing.sql
index 35d159f41b..171e0c439a 100644
--- a/src/test/regress/sql/indexing.sql
+++ b/src/test/regress/sql/indexing.sql
@@ -92,6 +92,7 @@ create table idxpart (a int) partition by range (a);
 create index on idxpart (a);
 create table idxpart1 partition of idxpart for values from (0) to (10);
 drop index idxpart1_a_idx;	-- no way
+drop index concurrently idxpart_a_idx;	-- unsupported
 drop index idxpart_a_idx;	-- both indexes go away
 select relname, relkind from pg_class
   where relname like 'idxpart%' order by relname;
-- 
2.20.1

