Remove public schema dependency for 10.0 upgrades

This commit contains a subset of the changes that should be cherry
picked to 10.0 releases.

(cherry picked from commit 8e9cc229ff)

src/backend/distributed/sql/citus--10.0-3--10.0-4.sql

@@ -1,5 +1,16 @@
+-- citus--10.0-3--10.0-4
+
+-- This migration file aims to fix 2 issues with upgrades on clusters
+
+-- 1. a bug in public schema dependency for citus_tables view.
 --
--- 10.0-3--10.0-4 was added later as a patch to fix a bug in our PG upgrade functions
+-- Users who do not have public schema in their clusters were unable to upgrade
+-- to Citus 10.x due to the citus_tables view that used to be created in public
+-- schema
+
+#include "udfs/citus_tables/10.0-4.sql"
+
+-- 2. a bug in our PG upgrade functions
 --
 -- Users who took the 9.5-2--10.0-1 upgrade path already have the fix, but users
 -- who took the 9.5-1--10.0-1 upgrade path do not. Hence, we repeat the CREATE OR

src/backend/distributed/sql/citus--9.5-1--10.0-4.sql

@@ -1,10 +1,16 @@
--- citus--9.5-1--10.0-1
+-- citus--9.5-1--10.0-4
+
+-- This migration file aims to fix the issues with upgrades on clusters without public schema.
+
+-- This file is created by the following command, and some more changes in a separate commit
+-- cat citus--9.5-1--10.0-1.sql citus--10.0-1--10.0-2.sql citus--10.0-2--10.0-3.sql > citus--9.5-1--10.0-4.sql
+
+-- copy of citus--9.5-1--10.0-1
 
 DROP FUNCTION pg_catalog.upgrade_to_reference_table(regclass);
 DROP FUNCTION IF EXISTS pg_catalog.citus_total_relation_size(regclass);
 
 #include "udfs/citus_total_relation_size/10.0-1.sql"
-#include "udfs/citus_tables/10.0-1.sql"
 #include "udfs/citus_finish_pg_upgrade/10.0-1.sql"
 #include "udfs/alter_distributed_table/10.0-1.sql"
 #include "udfs/alter_table_set_access_method/10.0-1.sql"
@@ -164,4 +170,48 @@ SELECT * FROM pg_catalog.citus_worker_stat_activity();
 ALTER VIEW citus.citus_worker_stat_activity SET SCHEMA pg_catalog;
 GRANT SELECT ON pg_catalog.citus_worker_stat_activity TO PUBLIC;
 
+-- copy of citus--10.0-1--10.0-2
+
+#include "../../columnar/sql/columnar--10.0-1--10.0-2.sql"
+
+-- copy of citus--10.0-2--10.0-3
+
+#include "udfs/citus_update_table_statistics/10.0-3.sql"
+
+CREATE OR REPLACE FUNCTION master_update_table_statistics(relation regclass)
+RETURNS VOID
+    LANGUAGE C STRICT
+    AS 'MODULE_PATHNAME', $$citus_update_table_statistics$$;
+COMMENT ON FUNCTION pg_catalog.master_update_table_statistics(regclass)
+	IS 'updates shard statistics of the given table';
+
+CREATE OR REPLACE FUNCTION pg_catalog.citus_get_active_worker_nodes(OUT node_name text, OUT node_port bigint)
+    RETURNS SETOF record
+    LANGUAGE C STRICT ROWS 100
+    AS 'MODULE_PATHNAME', $$citus_get_active_worker_nodes$$;
+COMMENT ON FUNCTION pg_catalog.citus_get_active_worker_nodes()
+    IS 'fetch set of active worker nodes';
+
+-- copy of citus--10.0-3--10.0-4
+
+-- This migration file aims to fix 2 issues with upgrades on clusters
+
+-- 1. a bug in public schema dependency for citus_tables view.
+--
+-- Users who do not have public schema in their clusters were unable to upgrade
+-- to Citus 10.x due to the citus_tables view that used to be created in public
+-- schema
+
+#include "udfs/citus_tables/10.0-4.sql"
+
+-- 2. a bug in our PG upgrade functions
+--
+-- Users who took the 9.5-2--10.0-1 upgrade path already have the fix, but users
+-- who took the 9.5-1--10.0-1 upgrade path do not. Hence, we repeat the CREATE OR
+-- REPLACE from the 9.5-2 definition for citus_prepare_pg_upgrade.
+
+#include "udfs/citus_prepare_pg_upgrade/9.5-2.sql"
+#include "udfs/citus_finish_pg_upgrade/10.0-4.sql"
+
+
 RESET search_path;

src/backend/distributed/sql/downgrades/citus--10.0-2--10.0-1.sql

@@ -1,4 +0,0 @@
-/* citus--10.0-2--10.0-1.sql */
-#include "../../../columnar/sql/downgrades/columnar--10.0-2--10.0-1.sql"
-
-REVOKE SELECT ON public.citus_tables FROM public;

src/backend/distributed/sql/downgrades/citus--10.0-3--10.0-2.sql

@@ -1,26 +0,0 @@
--- citus--10.0-3--10.0-2
--- this is a downgrade path that will revert the changes made in citus--10.0-2--10.0-3.sql
-
-DROP FUNCTION pg_catalog.citus_update_table_statistics(regclass);
-
-#include "../udfs/citus_update_table_statistics/10.0-1.sql"
-
-CREATE OR REPLACE FUNCTION master_update_table_statistics(relation regclass)
-RETURNS VOID AS $$
-DECLARE
-	colocated_tables regclass[];
-BEGIN
-	SELECT get_colocated_table_array(relation) INTO colocated_tables;
-
-	PERFORM
-		master_update_shard_statistics(shardid)
-	FROM
-		pg_dist_shard
-	WHERE
-		logicalrelid = ANY (colocated_tables);
-END;
-$$ LANGUAGE 'plpgsql';
-COMMENT ON FUNCTION master_update_table_statistics(regclass)
-	IS 'updates shard statistics of the given table and its colocated tables';
-
-DROP FUNCTION pg_catalog.citus_get_active_worker_nodes(OUT text, OUT bigint);

src/backend/distributed/sql/downgrades/citus--10.0-4--10.0-3.sql

@@ -1,9 +0,0 @@
---
--- 10.0-3--10.0-4 was added later as a patch to fix a bug in our PG upgrade functions
---
--- The upgrade fixes a bug in citus_(prepare|finish)_pg_upgrade. Given the old versions of
--- these functions contain a bug it is better to _not_ restore the old version and keep
--- the patched version of the function.
---
--- This is inline with the downgrade scripts for earlier versions of this patch
---

src/backend/distributed/sql/downgrades/citus--10.0-4--9.5-1.sql

@@ -1,4 +1,51 @@
--- citus--10.0-1--9.5-1
+-- citus--10.0-4--9.5-1
+
+-- This migration file aims to fix the issues with upgrades on clusters without public schema.
+
+-- This file is created by the following command, and some more changes in a separate commit
+-- cat citus--10.0-3--10.0-2.sql citus--10.0-2--10.0-1.sql citus--10.0-1--9.5-1.sql > citus--10.0-4--9.5-1.sql
+
+-- copy of citus--10.0-4--10.0-3
+--
+-- 10.0-3--10.0-4 was added later as a patch to fix a bug in our PG upgrade functions
+--
+-- The upgrade fixes a bug in citus_(prepare|finish)_pg_upgrade. Given the old versions of
+-- these functions contain a bug it is better to _not_ restore the old version and keep
+-- the patched version of the function.
+--
+-- This is inline with the downgrade scripts for earlier versions of this patch
+--
+
+-- copy of citus--10.0-3--10.0-2
+-- this is a downgrade path that will revert the changes made in citus--10.0-2--10.0-3.sql
+
+DROP FUNCTION pg_catalog.citus_update_table_statistics(regclass);
+
+#include "../udfs/citus_update_table_statistics/10.0-1.sql"
+
+CREATE OR REPLACE FUNCTION master_update_table_statistics(relation regclass)
+RETURNS VOID AS $$
+DECLARE
+	colocated_tables regclass[];
+BEGIN
+	SELECT get_colocated_table_array(relation) INTO colocated_tables;
+
+	PERFORM
+		master_update_shard_statistics(shardid)
+	FROM
+		pg_dist_shard
+	WHERE
+		logicalrelid = ANY (colocated_tables);
+END;
+$$ LANGUAGE 'plpgsql';
+COMMENT ON FUNCTION master_update_table_statistics(regclass)
+	IS 'updates shard statistics of the given table and its colocated tables';
+
+DROP FUNCTION pg_catalog.citus_get_active_worker_nodes(OUT text, OUT bigint);
+/* copy of citus--10.0-2--10.0-1.sql */
+#include "../../../columnar/sql/downgrades/columnar--10.0-2--10.0-1.sql"
+
+-- copy of citus--10.0-1--9.5-1
 
 -- In Citus 10.0, we added another internal udf (notify_constraint_dropped)
 -- to be called by citus_drop_trigger. Since this script is executed when
@@ -18,7 +65,8 @@ DROP FUNCTION pg_catalog.notify_constraint_dropped();
 
 #include "../../../columnar/sql/downgrades/columnar--10.0-1--9.5-1.sql"
 
-DROP VIEW public.citus_tables;
+DROP VIEW IF EXISTS pg_catalog.citus_tables;
+DROP VIEW IF EXISTS public.citus_tables;
 DROP FUNCTION pg_catalog.alter_distributed_table(regclass, text, int, text, boolean);
 DROP FUNCTION pg_catalog.alter_table_set_access_method(regclass, text);
 DROP FUNCTION pg_catalog.citus_total_relation_size(regclass,boolean);

src/backend/distributed/sql/udfs/citus_tables/10.0-4.sql

@@ -0,0 +1,38 @@
+DO $$
+declare
+citus_tables_create_query text;
+BEGIN
+citus_tables_create_query=$CTCQ$
+    CREATE OR REPLACE VIEW %I.citus_tables AS
+    SELECT
+        logicalrelid AS table_name,
+        CASE WHEN partkey IS NOT NULL THEN 'distributed' ELSE 'reference' END AS citus_table_type,
+        coalesce(column_to_column_name(logicalrelid, partkey), '<none>') AS distribution_column,
+        colocationid AS colocation_id,
+        pg_size_pretty(citus_total_relation_size(logicalrelid, fail_on_error := false)) AS table_size,
+        (select count(*) from pg_dist_shard where logicalrelid = p.logicalrelid) AS shard_count,
+        pg_get_userbyid(relowner) AS table_owner,
+        amname AS access_method
+    FROM
+        pg_dist_partition p
+    JOIN
+        pg_class c ON (p.logicalrelid = c.oid)
+    LEFT JOIN
+        pg_am a ON (a.oid = c.relam)
+    WHERE
+        partkey IS NOT NULL OR repmodel = 't'
+    ORDER BY
+        logicalrelid::text;
+$CTCQ$;
+
+IF EXISTS (SELECT 1 FROM pg_namespace WHERE nspname = 'public') THEN
+    EXECUTE format(citus_tables_create_query, 'public');
+    GRANT SELECT ON public.citus_tables TO public;
+ELSE
+    EXECUTE format(citus_tables_create_query, 'citus');
+    ALTER VIEW citus.citus_tables SET SCHEMA pg_catalog;
+    GRANT SELECT ON pg_catalog.citus_tables TO public;
+END IF;
+
+END;
+$$;

src/backend/distributed/sql/udfs/citus_tables/latest.sql

@@ -1,4 +1,9 @@
-CREATE VIEW public.citus_tables AS
+DO $$
+declare
+citus_tables_create_query text;
+BEGIN
+citus_tables_create_query=$CTCQ$
+    CREATE OR REPLACE VIEW %I.citus_tables AS
     SELECT
         logicalrelid AS table_name,
         CASE WHEN partkey IS NOT NULL THEN 'distributed' ELSE 'reference' END AS citus_table_type,
@@ -18,3 +23,16 @@ WHERE
         partkey IS NOT NULL OR repmodel = 't'
     ORDER BY
         logicalrelid::text;
+$CTCQ$;
+
+IF EXISTS (SELECT 1 FROM pg_namespace WHERE nspname = 'public') THEN
+    EXECUTE format(citus_tables_create_query, 'public');
+    GRANT SELECT ON public.citus_tables TO public;
+ELSE
+    EXECUTE format(citus_tables_create_query, 'citus');
+    ALTER VIEW citus.citus_tables SET SCHEMA pg_catalog;
+    GRANT SELECT ON pg_catalog.citus_tables TO public;
+END IF;
+
+END;
+$$;

src/test/regress/expected/multi_extension.out

@@ -16,6 +16,7 @@ SELECT substring(:'server_version', '\d+')::int > 11 AS version_above_eleven;
 (1 row)
 
 SET citus.next_shard_id TO 580000;
+CREATE SCHEMA multi_extension;
 SELECT $definition$
 CREATE OR REPLACE FUNCTION test.maintenance_worker()
     RETURNS pg_stat_activity
@@ -42,13 +43,14 @@ END;
 $$;
 $definition$ create_function_test_maintenance_worker
 \gset
-CREATE TABLE prev_objects(description text);
+CREATE TABLE multi_extension.prev_objects(description text);
-CREATE TABLE extension_diff(previous_object text COLLATE "C",
+CREATE TABLE multi_extension.extension_diff(previous_object text COLLATE "C",
                             current_object text COLLATE "C");
-CREATE FUNCTION print_extension_changes()
+CREATE FUNCTION multi_extension.print_extension_changes()
 RETURNS TABLE(previous_object text, current_object text)
 AS $func$
 BEGIN
+    SET LOCAL search_path TO multi_extension;
 	TRUNCATE TABLE extension_diff;
 
 	CREATE TABLE current_objects AS
@@ -130,7 +132,7 @@ ALTER EXTENSION citus UPDATE TO '9.1-1';
 ALTER EXTENSION citus UPDATE TO '9.2-1';
 ALTER EXTENSION citus UPDATE TO '9.2-2';
 -- Snapshot of state at 9.2-2
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object |                                                                                                        current_object
 ---------------------------------------------------------------------
                  | event trigger citus_cascade_to_partition
@@ -327,7 +329,7 @@ SELECT * FROM print_extension_changes();
 ALTER EXTENSION citus UPDATE TO '9.2-4';
 ALTER EXTENSION citus UPDATE TO '9.2-2';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
@@ -342,7 +344,7 @@ ALTER EXTENSION citus UPDATE TO '9.3-1';
 ERROR:  extension "citus" has no update path from version "9.2-2" to version "9.3-1"
 ALTER EXTENSION citus UPDATE TO '9.2-4';
 -- Snapshot of state at 9.2-4
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
@@ -351,14 +353,14 @@ SELECT * FROM print_extension_changes();
 ALTER EXTENSION citus UPDATE TO '9.3-2';
 ALTER EXTENSION citus UPDATE TO '9.2-4';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
 -- Snapshot of state at 9.3-2
 ALTER EXTENSION citus UPDATE TO '9.3-2';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
                   previous_object                  |                            current_object
 ---------------------------------------------------------------------
  function citus_extradata_container(internal) void |
@@ -374,14 +376,14 @@ SELECT * FROM print_extension_changes();
 ALTER EXTENSION citus UPDATE TO '9.4-1';
 ALTER EXTENSION citus UPDATE TO '9.3-2';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
 -- Snapshot of state at 9.4-1
 ALTER EXTENSION citus UPDATE TO '9.4-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object |                                                    current_object
 ---------------------------------------------------------------------
                  | function worker_last_saved_explain_analyze() TABLE(explain_analyze_output text, execution_duration double precision)
@@ -393,20 +395,20 @@ ALTER EXTENSION citus UPDATE TO '9.4-2';
 ALTER EXTENSION citus UPDATE TO '9.4-1';
 -- Should be empty result, even though the downgrade doesn't undo the upgrade, the
 -- function signature doesn't change, which is reflected here.
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
 ALTER EXTENSION citus UPDATE TO '9.4-2';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
 -- Snapshot of state at 9.4-1
 ALTER EXTENSION citus UPDATE TO '9.4-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
@@ -437,14 +439,14 @@ ROLLBACK;
 -- now we can downgrade as there is no citus local table
 ALTER EXTENSION citus UPDATE TO '9.4-1';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
 -- Snapshot of state at 9.5-1
 ALTER EXTENSION citus UPDATE TO '9.5-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
                              previous_object                              |                             current_object
 ---------------------------------------------------------------------
  function master_drop_sequences(text[]) void                              |
@@ -464,36 +466,38 @@ ALTER EXTENSION citus UPDATE TO '9.5-2';
 ALTER EXTENSION citus UPDATE TO '9.5-1';
 -- Should be empty result, even though the downgrade doesn't undo the upgrade, the
 -- function signature doesn't change, which is reflected here.
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
 ALTER EXTENSION citus UPDATE TO '9.5-2';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
 -- Snapshot of state at 9.5-1
 ALTER EXTENSION citus UPDATE TO '9.5-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
--- Test downgrade to 9.5-1 from 10.0-1
+-- We removed the upgrade paths to 10.0-1, 10.0-2 and 10.0-3 due to a bug that blocked
-ALTER EXTENSION citus UPDATE TO '10.0-1';
+-- upgrades to 10.0, Therefore we test upgrades to 10.0-4 instead
+-- Test downgrade to 9.5-1 from 10.0-4
+ALTER EXTENSION citus UPDATE TO '10.0-4';
 ALTER EXTENSION citus UPDATE TO '9.5-1';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
--- Snapshot of state at 10.0-1
+-- Snapshot of state at 10.0-4
-ALTER EXTENSION citus UPDATE TO '10.0-1';
+ALTER EXTENSION citus UPDATE TO '10.0-4';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
                                    previous_object                                    |                                                current_object
 ---------------------------------------------------------------------
  function citus_total_relation_size(regclass) bigint                                  |
@@ -534,6 +538,7 @@ SELECT * FROM print_extension_changes();
                                                                                       | function citus_dist_shard_cache_invalidate() trigger
                                                                                       | function citus_drain_node(text,integer,citus.shard_transfer_mode,name) void
                                                                                       | function citus_drop_all_shards(regclass,text,text) integer
+                                                                                      | function citus_get_active_worker_nodes() SETOF record
                                                                                       | function citus_internal.columnar_ensure_objects_exist() void
                                                                                       | function citus_move_shard_placement(bigint,text,integer,text,integer,citus.shard_transfer_mode) void
                                                                                       | function citus_remove_node(text,integer) void
@@ -561,72 +566,50 @@ SELECT * FROM print_extension_changes();
                                                                                       | table columnar.options
                                                                                       | table columnar.stripe
                                                                                       | view citus_shards
-                                                                                      | view citus_tables
+                                                                                      | view public.citus_tables
                                                                                       | view time_partitions
-(67 rows)
+(68 rows)
 
--- Test downgrade to 10.0-1 from 10.0-2
+-- check that we depend on the existence of public schema, and we can not drop it now
-ALTER EXTENSION citus UPDATE TO '10.0-2';
+DROP SCHEMA public;
-ALTER EXTENSION citus UPDATE TO '10.0-1';
+ERROR:  cannot drop schema public because other objects depend on it
--- Should be empty result since upgrade+downgrade should be a no-op
+DETAIL:  extension citus depends on schema public
-SELECT * FROM print_extension_changes();
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.
- previous_object | current_object
+-- verify that citus_tables view is on pg_catalog if public schema is absent.
----------------------------------------------------------------------
+ALTER EXTENSION citus UPDATE TO '9.5-1';
-(0 rows)
+DROP SCHEMA public;
-
--- Snapshot of state at 10.0-2
-ALTER EXTENSION citus UPDATE TO '10.0-2';
-SELECT * FROM print_extension_changes();
- previous_object | current_object
----------------------------------------------------------------------
-(0 rows)
-
--- Test downgrade to 10.0-2 from 10.0-3
-ALTER EXTENSION citus UPDATE TO '10.0-3';
-ALTER EXTENSION citus UPDATE TO '10.0-2';
--- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
- previous_object | current_object
----------------------------------------------------------------------
-(0 rows)
-
--- Snapshot of state at 10.0-3
-ALTER EXTENSION citus UPDATE TO '10.0-3';
-SELECT * FROM print_extension_changes();
- previous_object |                    current_object
----------------------------------------------------------------------
-                 | function citus_get_active_worker_nodes() SETOF record
-(1 row)
-
--- Test downgrade to 10.0-3 from 10.0-4
 ALTER EXTENSION citus UPDATE TO '10.0-4';
-ALTER EXTENSION citus UPDATE TO '10.0-3';
+SELECT * FROM multi_extension.print_extension_changes();
--- Should be empty result, even though the downgrade doesn't undo the upgrade, the
--- function signature doesn't change, which is reflected here.
-SELECT * FROM print_extension_changes();
       previous_object      |   current_object
 ---------------------------------------------------------------------
-(0 rows)
+ view public.citus_tables  |
+                           | view citus_tables
+(2 rows)
 
--- Snapshot of state at 10.0-4
+-- recreate public schema, and recreate citus_tables in the public schema by default
+CREATE SCHEMA public;
+GRANT ALL ON SCHEMA public TO public;
+ALTER EXTENSION citus UPDATE TO '9.5-1';
 ALTER EXTENSION citus UPDATE TO '10.0-4';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
   previous_object   |      current_object
 ---------------------------------------------------------------------
-(0 rows)
+ view citus_tables  |
+                    | view public.citus_tables
+(2 rows)
 
 -- Test downgrade to 10.0-4 from 10.1-1
 ALTER EXTENSION citus UPDATE TO '10.1-1';
 ALTER EXTENSION citus UPDATE TO '10.0-4';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
  previous_object | current_object
 ---------------------------------------------------------------------
 (0 rows)
 
 -- Snapshot of state at 10.1-1
 ALTER EXTENSION citus UPDATE TO '10.1-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
                                                                                                         previous_object                                                                                                        |                                                                                                                          current_object
 ---------------------------------------------------------------------
  function citus_add_rebalance_strategy(name,regproc,regproc,regproc,real,real) void                                                                                                                                            |
@@ -646,7 +629,7 @@ SELECT * FROM print_extension_changes();
                                                                                                                                                                                                                                | function worker_partitioned_table_size(regclass) bigint
 (15 rows)
 
-DROP TABLE prev_objects, extension_diff;
+DROP TABLE multi_extension.prev_objects, multi_extension.extension_diff;
 -- show running version
 SHOW citus.version;
  citus.version
@@ -989,3 +972,7 @@ SELECT count(*) FROM pg_stat_activity WHERE application_name = 'Citus Maintenanc
 (1 row)
 
 DROP TABLE version_mismatch_table;
+DROP SCHEMA multi_extension;
+ERROR:  cannot drop schema multi_extension because other objects depend on it
+DETAIL:  function multi_extension.print_extension_changes() depends on schema multi_extension
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.

src/test/regress/sql/multi_extension.sql

@@ -13,6 +13,7 @@ SHOW server_version \gset
 SELECT substring(:'server_version', '\d+')::int > 11 AS version_above_eleven;
 
 SET citus.next_shard_id TO 580000;
+CREATE SCHEMA multi_extension;
 
 SELECT $definition$
 CREATE OR REPLACE FUNCTION test.maintenance_worker()
@@ -41,14 +42,15 @@ $$;
 $definition$ create_function_test_maintenance_worker
 \gset
 
-CREATE TABLE prev_objects(description text);
+CREATE TABLE multi_extension.prev_objects(description text);
-CREATE TABLE extension_diff(previous_object text COLLATE "C",
+CREATE TABLE multi_extension.extension_diff(previous_object text COLLATE "C",
                             current_object text COLLATE "C");
 
-CREATE FUNCTION print_extension_changes()
+CREATE FUNCTION multi_extension.print_extension_changes()
 RETURNS TABLE(previous_object text, current_object text)
 AS $func$
 BEGIN
+    SET LOCAL search_path TO multi_extension;
 	TRUNCATE TABLE extension_diff;
 
 	CREATE TABLE current_objects AS
@@ -128,13 +130,13 @@ ALTER EXTENSION citus UPDATE TO '9.1-1';
 ALTER EXTENSION citus UPDATE TO '9.2-1';
 ALTER EXTENSION citus UPDATE TO '9.2-2';
 -- Snapshot of state at 9.2-2
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Test downgrade to 9.2-2 from 9.2-4
 ALTER EXTENSION citus UPDATE TO '9.2-4';
 ALTER EXTENSION citus UPDATE TO '9.2-2';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 /*
  * As we mistakenly bumped schema version to 9.3-1 in a bad release, we support
@@ -146,41 +148,41 @@ ALTER EXTENSION citus UPDATE TO '9.3-1';
 
 ALTER EXTENSION citus UPDATE TO '9.2-4';
 -- Snapshot of state at 9.2-4
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Test downgrade to 9.2-4 from 9.3-2
 ALTER EXTENSION citus UPDATE TO '9.3-2';
 ALTER EXTENSION citus UPDATE TO '9.2-4';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Snapshot of state at 9.3-2
 ALTER EXTENSION citus UPDATE TO '9.3-2';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Test downgrade to 9.3-2 from 9.4-1
 ALTER EXTENSION citus UPDATE TO '9.4-1';
 ALTER EXTENSION citus UPDATE TO '9.3-2';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Snapshot of state at 9.4-1
 ALTER EXTENSION citus UPDATE TO '9.4-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Test upgrade paths for backported citus_pg_upgrade functions
 ALTER EXTENSION citus UPDATE TO '9.4-2';
 ALTER EXTENSION citus UPDATE TO '9.4-1';
 -- Should be empty result, even though the downgrade doesn't undo the upgrade, the
 -- function signature doesn't change, which is reflected here.
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 ALTER EXTENSION citus UPDATE TO '9.4-2';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Snapshot of state at 9.4-1
 ALTER EXTENSION citus UPDATE TO '9.4-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Test downgrade to 9.4-1 from 9.5-1
 ALTER EXTENSION citus UPDATE TO '9.5-1';
@@ -198,78 +200,66 @@ ROLLBACK;
 ALTER EXTENSION citus UPDATE TO '9.4-1';
 
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Snapshot of state at 9.5-1
 ALTER EXTENSION citus UPDATE TO '9.5-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Test upgrade paths for backported citus_pg_upgrade functions
 ALTER EXTENSION citus UPDATE TO '9.5-2';
 ALTER EXTENSION citus UPDATE TO '9.5-1';
 -- Should be empty result, even though the downgrade doesn't undo the upgrade, the
 -- function signature doesn't change, which is reflected here.
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 ALTER EXTENSION citus UPDATE TO '9.5-2';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Snapshot of state at 9.5-1
 ALTER EXTENSION citus UPDATE TO '9.5-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
--- Test downgrade to 9.5-1 from 10.0-1
+-- We removed the upgrade paths to 10.0-1, 10.0-2 and 10.0-3 due to a bug that blocked
-ALTER EXTENSION citus UPDATE TO '10.0-1';
+-- upgrades to 10.0, Therefore we test upgrades to 10.0-4 instead
+
+-- Test downgrade to 9.5-1 from 10.0-4
+ALTER EXTENSION citus UPDATE TO '10.0-4';
 ALTER EXTENSION citus UPDATE TO '9.5-1';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
-
--- Snapshot of state at 10.0-1
-ALTER EXTENSION citus UPDATE TO '10.0-1';
-SELECT * FROM print_extension_changes();
-
--- Test downgrade to 10.0-1 from 10.0-2
-ALTER EXTENSION citus UPDATE TO '10.0-2';
-ALTER EXTENSION citus UPDATE TO '10.0-1';
--- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
-
--- Snapshot of state at 10.0-2
-ALTER EXTENSION citus UPDATE TO '10.0-2';
-SELECT * FROM print_extension_changes();
-
--- Test downgrade to 10.0-2 from 10.0-3
-ALTER EXTENSION citus UPDATE TO '10.0-3';
-ALTER EXTENSION citus UPDATE TO '10.0-2';
--- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
-
--- Snapshot of state at 10.0-3
-ALTER EXTENSION citus UPDATE TO '10.0-3';
-SELECT * FROM print_extension_changes();
-
--- Test downgrade to 10.0-3 from 10.0-4
-ALTER EXTENSION citus UPDATE TO '10.0-4';
-ALTER EXTENSION citus UPDATE TO '10.0-3';
--- Should be empty result, even though the downgrade doesn't undo the upgrade, the
--- function signature doesn't change, which is reflected here.
-SELECT * FROM print_extension_changes();
 
 -- Snapshot of state at 10.0-4
 ALTER EXTENSION citus UPDATE TO '10.0-4';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
+
+-- check that we depend on the existence of public schema, and we can not drop it now
+DROP SCHEMA public;
+
+-- verify that citus_tables view is on pg_catalog if public schema is absent.
+ALTER EXTENSION citus UPDATE TO '9.5-1';
+DROP SCHEMA public;
+ALTER EXTENSION citus UPDATE TO '10.0-4';
+SELECT * FROM multi_extension.print_extension_changes();
+
+-- recreate public schema, and recreate citus_tables in the public schema by default
+CREATE SCHEMA public;
+GRANT ALL ON SCHEMA public TO public;
+ALTER EXTENSION citus UPDATE TO '9.5-1';
+ALTER EXTENSION citus UPDATE TO '10.0-4';
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Test downgrade to 10.0-4 from 10.1-1
 ALTER EXTENSION citus UPDATE TO '10.1-1';
 ALTER EXTENSION citus UPDATE TO '10.0-4';
 -- Should be empty result since upgrade+downgrade should be a no-op
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
 -- Snapshot of state at 10.1-1
 ALTER EXTENSION citus UPDATE TO '10.1-1';
-SELECT * FROM print_extension_changes();
+SELECT * FROM multi_extension.print_extension_changes();
 
-DROP TABLE prev_objects, extension_diff;
+DROP TABLE multi_extension.prev_objects, multi_extension.extension_diff;
 
 -- show running version
 SHOW citus.version;
@@ -537,3 +527,4 @@ FROM test.maintenance_worker();
 SELECT count(*) FROM pg_stat_activity WHERE application_name = 'Citus Maintenance Daemon';
 
 DROP TABLE version_mismatch_table;
+DROP SCHEMA multi_extension;