From 91473635db26522d6a9352b0c7b60a08e7c3645d Mon Sep 17 00:00:00 2001
From: Ying Xu <32597660+yxu2162@users.noreply.github.com>
Date: Wed, 17 Aug 2022 15:12:42 -0700
Subject: [PATCH] [Columnar] Check for existence of Citus before creating
 Citus_Columnar (#6178)

* Added a check to see if Citus has already been loaded before creating citus_columnar

* added tests
---
 src/backend/distributed/commands/extension.c  | 2 +-
 src/test/regress/expected/multi_extension.out | 5 +++++
 src/test/regress/sql/multi_extension.sql      | 3 +++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/backend/distributed/commands/extension.c b/src/backend/distributed/commands/extension.c
index 542a41c10..ac4bf135e 100644
--- a/src/backend/distributed/commands/extension.c
+++ b/src/backend/distributed/commands/extension.c
@@ -778,7 +778,7 @@ PreprocessCreateExtensionStmtForCitusColumnar(Node *parsetree)
 		}
 
 		/*citus version >= 11.1 requires install citus_columnar first*/
-		if (versionNumber >= 1110)
+		if (versionNumber >= 1110 && !CitusHasBeenLoaded())
 		{
 			if (get_extension_oid("citus_columnar", true) == InvalidOid)
 			{
diff --git a/src/test/regress/expected/multi_extension.out b/src/test/regress/expected/multi_extension.out
index 59344c2e3..a0791472b 100644
--- a/src/test/regress/expected/multi_extension.out
+++ b/src/test/regress/expected/multi_extension.out
@@ -1095,6 +1095,11 @@ SELECT * FROM multi_extension.print_extension_changes();
 ---------------------------------------------------------------------
 (0 rows)
 
+-- Test CREATE EXTENSION when Citus already exists but Citus_Columnar does not. Should skip
+CREATE EXTENSION IF NOT EXISTS citus;
+NOTICE:  extension "citus" already exists, skipping
+CREATE EXTENSION citus;
+ERROR:  extension "citus" already exists
 -- Snapshot of state at 11.1-1
 ALTER EXTENSION citus UPDATE TO '11.1-1';
 SELECT * FROM multi_extension.print_extension_changes();
diff --git a/src/test/regress/sql/multi_extension.sql b/src/test/regress/sql/multi_extension.sql
index b6f87e214..106b8bd4a 100644
--- a/src/test/regress/sql/multi_extension.sql
+++ b/src/test/regress/sql/multi_extension.sql
@@ -500,6 +500,9 @@ ALTER EXTENSION citus UPDATE TO '11.0-4';
 -- Should be empty result since upgrade+downgrade should be a no-op
 SELECT * FROM multi_extension.print_extension_changes();
 
+-- Test CREATE EXTENSION when Citus already exists but Citus_Columnar does not. Should skip
+CREATE EXTENSION IF NOT EXISTS citus;
+CREATE EXTENSION citus;
 -- Snapshot of state at 11.1-1
 ALTER EXTENSION citus UPDATE TO '11.1-1';
 SELECT * FROM multi_extension.print_extension_changes();