Disallow index DDL on worker if coord not in metadata

src/backend/distributed/commands/utility_hook.c

@@ -1126,6 +1126,20 @@ ExecuteDistributedDDLJob(DDLJob *ddlJob)
 		EnsureCoordinator();
 	}
 
+	if (!IsCoordinator() && !CoordinatorAddedAsWorkerNode() &&
+		!EnableAcquiringUnsafeLockFromWorkers)
+	{
+		ereport(ERROR,
+				(errmsg(
+					 "Cannot execute DDL command from a worker node since the "
+					 "coordinator is not in the metadata."),
+				 errhint(
+					 "Either run this command on the coordinator or add the coordinator "
+					 "in the metadata by using: SELECT citus_set_coordinator_host('<hostname>', <port>);\n"
+					 "Alternatively, though it is not recommended, you can allow this command by running: "
+					 "SET citus.allow_unsafe_locks_from_workers TO 'on';")));
+	}
+
 	ObjectAddress targetObjectAddress = ddlJob->targetObjectAddress;
 
 	if (OidIsValid(targetObjectAddress.classId))

src/test/regress/expected/isolation_index_vs_all_on_mx.out

@@ -1,6 +1,11 @@
 Parsed test spec with 4 sessions
 
 starting permutation: w1-start-session-level-connection w1-begin-on-worker w2-start-session-level-connection w2-begin-on-worker w1-create-named-index w2-create-named-index w1-commit-worker w2-commit-worker w1-stop-connection w2-stop-connection coord-print-index-count
+citus_set_coordinator_host
+---------------------------------------------------------------------
+
+(1 row)
+
 step w1-start-session-level-connection:
  SELECT start_session_level_connection_to_node('localhost', 57637);
 
@@ -97,8 +102,18 @@ result
      2
 (4 rows)
 
+citus_remove_node
+---------------------------------------------------------------------
+
+(1 row)
+
 
 starting permutation: w1-start-session-level-connection w1-begin-on-worker w2-start-session-level-connection w2-begin-on-worker w1-create-unnamed-index w2-create-unnamed-index w1-commit-worker w1-stop-connection w2-stop-connection coord-print-index-count
+citus_set_coordinator_host
+---------------------------------------------------------------------
+
+(1 row)
+
 step w1-start-session-level-connection:
  SELECT start_session_level_connection_to_node('localhost', 57637);
 
@@ -184,77 +199,18 @@ result
      1
 (4 rows)
 
-
+citus_remove_node
-starting permutation: w1-start-session-level-connection w2-start-session-level-connection w1-create-index-concurrently w2-create-index-concurrently w1-empty w1-stop-connection w2-stop-connection coord-print-index-count
-step w1-start-session-level-connection:
- SELECT start_session_level_connection_to_node('localhost', 57637);
-
-start_session_level_connection_to_node
 ---------------------------------------------------------------------
 
 (1 row)
 
-step w2-start-session-level-connection:
- SELECT start_session_level_connection_to_node('localhost', 57638);
-
-start_session_level_connection_to_node
----------------------------------------------------------------------
-
-(1 row)
-
-step w1-create-index-concurrently:
- SELECT run_commands_on_session_level_connection_to_node('CREATE INDEX CONCURRENTLY dist_table_index ON dist_table(id)');
- <waiting ...>
-step w2-create-index-concurrently: 
- SELECT run_commands_on_session_level_connection_to_node('CREATE INDEX CONCURRENTLY dist_table_index_2 ON dist_table(id)');
- <waiting ...>
-step w1-create-index-concurrently: <... completed>
-run_commands_on_session_level_connection_to_node
----------------------------------------------------------------------
-
-(1 row)
-
-step w1-empty:
-step w2-create-index-concurrently: <... completed>
-run_commands_on_session_level_connection_to_node
----------------------------------------------------------------------
-
-(1 row)
-
-step w1-stop-connection:
- SELECT stop_session_level_connection_to_node();
-
-stop_session_level_connection_to_node
----------------------------------------------------------------------
-
-(1 row)
-
-step w2-stop-connection:
- SELECT stop_session_level_connection_to_node();
-
-stop_session_level_connection_to_node
----------------------------------------------------------------------
-
-(1 row)
-
-step coord-print-index-count:
- SELECT
-  result
- FROM
-  run_command_on_placements('dist_table', 'select count(*) from pg_indexes WHERE tablename = ''%s''')
- ORDER BY
-  nodeport;
-
-result
----------------------------------------------------------------------
-     2
-     2
-     2
-     2
-(4 rows)
-
 
 starting permutation: w1-start-session-level-connection w1-create-named-index w1-begin-on-worker w1-delete coord-begin coord-short-statement-timeout coord-take-lock w1-reindex deadlock-checker-call coord-rollback w1-commit-worker w1-stop-connection
+citus_set_coordinator_host
+---------------------------------------------------------------------
+
+(1 row)
+
 step w1-start-session-level-connection:
  SELECT start_session_level_connection_to_node('localhost', 57637);
 
@@ -298,22 +254,23 @@ step coord-take-lock:
  <waiting ...>
 step w1-reindex: 
  SELECT run_commands_on_session_level_connection_to_node('REINDEX INDEX dist_table_index');
+ <waiting ...>
+step deadlock-checker-call: 
+  SELECT check_distributed_deadlocks();
 
+check_distributed_deadlocks
+---------------------------------------------------------------------
+t
+(1 row)
+
+step coord-take-lock: <... completed>
+ERROR:  canceling the transaction since it was involved in a distributed deadlock
+step w1-reindex: <... completed>
 run_commands_on_session_level_connection_to_node
 ---------------------------------------------------------------------
 
 (1 row)
 
-step deadlock-checker-call:
-  SELECT check_distributed_deadlocks();
-
-check_distributed_deadlocks
----------------------------------------------------------------------
-f
-(1 row)
-
-step coord-take-lock: <... completed>
-ERROR:  canceling statement due to statement timeout
 step coord-rollback:
  ROLLBACK;
 
@@ -333,3 +290,8 @@ stop_session_level_connection_to_node
 
 (1 row)
 
+citus_remove_node
+---------------------------------------------------------------------
+
+(1 row)
+

src/test/regress/spec/isolation_index_vs_all_on_mx.spec

@@ -5,11 +5,13 @@ setup
 	CREATE TABLE dist_table(id int, data int);
 	SELECT create_distributed_table('dist_table', 'id');
 	COPY dist_table FROM PROGRAM 'echo 1, 10 && echo 2, 20 && echo 3, 30 && echo 4, 40 && echo 5, 50' WITH CSV;
+	SELECT citus_set_coordinator_host('localhost', 57636);
 }
 
 teardown
 {
 	DROP TABLE IF EXISTS dist_table CASCADE;
+	SELECT citus_remove_node('localhost', 57636);
 }
 
 session "w1"
@@ -34,14 +36,6 @@ step "w1-create-unnamed-index"
 	SELECT run_commands_on_session_level_connection_to_node('CREATE INDEX ON dist_table(id,data)');
 }
 
-step "w1-create-index-concurrently"
-{
-	SELECT run_commands_on_session_level_connection_to_node('CREATE INDEX CONCURRENTLY dist_table_index ON dist_table(id)');
-}
-
-// an empty step to have consistent output for CONCURRENTLY
-step "w1-empty" {}
-
 step "w1-reindex"
 {
 	SELECT run_commands_on_session_level_connection_to_node('REINDEX INDEX dist_table_index');
@@ -85,11 +79,6 @@ step "w2-create-unnamed-index"
 	SELECT run_commands_on_session_level_connection_to_node('CREATE INDEX ON dist_table(id,data)');
 }
 
-step "w2-create-index-concurrently"
-{
-	SELECT run_commands_on_session_level_connection_to_node('CREATE INDEX CONCURRENTLY dist_table_index_2 ON dist_table(id)');
-}
-
 step "w2-commit-worker"
 {
 	SELECT run_commands_on_session_level_connection_to_node('COMMIT');
@@ -153,14 +142,6 @@ permutation "w1-start-session-level-connection" "w1-begin-on-worker" // open tra
 			"w1-stop-connection" "w2-stop-connection"				 // close connections to workers
 			"coord-print-index-count"					 			 // show indexes on coordinator
 
-permutation "w1-start-session-level-connection"			 		 	 // start session on worker 1
-			"w2-start-session-level-connection"			 		 	 // start session on worker 2
-			"w1-create-index-concurrently"(*)						 // create both indexes with concurrently option
-			"w2-create-index-concurrently"(*)
-			"w1-empty" 												 // empty steps to have consistent output for CONCURRENTLY
-			"w1-stop-connection" "w2-stop-connection"				 // close connections to workers
-			"coord-print-index-count"					 			 // show indexes on coordinator
-
 // the following permutation is expected to fail with a distributed deadlock. However, we do not detect the deadlock, and get blocked until statement_timeout.
 permutation "w1-start-session-level-connection"				 		 // start session on worker 1 only
 			"w1-create-named-index"									 // create index on worker 1