Add force option to master_remove_node

We can now remove nodes from cluster regardless of them
having an active shard placement.

src/backend/distributed/Makefile

@@ -9,7 +9,7 @@ EXTVERSIONS = 5.0 5.0-1 5.0-2  \
 	5.1-1 5.1-2 5.1-3 5.1-4 5.1-5 5.1-6 5.1-7 5.1-8 \
 	5.2-1 5.2-2 5.2-3 5.2-4 \
 	6.0-1 6.0-2 6.0-3 6.0-4 6.0-5 6.0-6 6.0-7 6.0-8 6.0-9 6.0-10 6.0-11 6.0-12 6.0-13 6.0-14 6.0-15 6.0-16 6.0-17 6.0-18 \
-	6.1-1 6.1-2 6.1-3 6.1-4 6.1-5 6.1-6 6.1-7 6.1-8 6.1-9 6.1-10 6.1-11 6.1-12
+	6.1-1 6.1-2 6.1-3 6.1-4 6.1-5 6.1-6 6.1-7 6.1-8 6.1-9 6.1-10 6.1-11 6.1-12 6.1-13
 
 # All citus--*.sql files in the source directory
 DATA = $(patsubst $(citus_abs_srcdir)/%.sql,%.sql,$(wildcard $(citus_abs_srcdir)/$(EXTENSION)--*--*.sql))
@@ -119,6 +119,8 @@ $(EXTENSION)--6.1-11.sql: $(EXTENSION)--6.1-10.sql $(EXTENSION)--6.1-10--6.1-11.
 	cat $^ > $@
 $(EXTENSION)--6.1-12.sql: $(EXTENSION)--6.1-11.sql $(EXTENSION)--6.1-11--6.1-12.sql
 	cat $^ > $@
+$(EXTENSION)--6.1-13.sql: $(EXTENSION)--6.1-12.sql $(EXTENSION)--6.1-12--6.1-13.sql
+	cat $^ > $@
 
 NO_PGXS = 1
 

src/backend/distributed/citus--6.1-12--6.1-13.sql

@@ -0,0 +1,15 @@
+/* citus--6.1-12--6.1-13.sql */
+
+SET search_path = 'pg_catalog';
+
+DROP FUNCTION IF EXISTS master_remove_node(nodename text, nodeport integer);
+
+CREATE FUNCTION master_remove_node(nodename text, nodeport integer,
+								   force bool DEFAULT false)
+	RETURNS void
+	LANGUAGE C STRICT
+	AS 'MODULE_PATHNAME', $$master_remove_node$$;
+COMMENT ON FUNCTION master_remove_node(nodename text, nodeport integer, force bool)
+	IS 'remove node from the cluster';
+    
+RESET search_path;

src/backend/distributed/citus.control

@@ -1,6 +1,6 @@
 # Citus extension
 comment = 'Citus distributed database'
-default_version = '6.1-12'
+default_version = '6.1-13'
 module_pathname = '$libdir/citus'
 relocatable = false
 schema = pg_catalog

src/backend/distributed/utils/node_metadata.c

@@ -111,6 +111,7 @@ master_remove_node(PG_FUNCTION_ARGS)
 {
 	text *nodeName = PG_GETARG_TEXT_P(0);
 	int32 nodePort = PG_GETARG_INT32(1);
+	bool force = PG_GETARG_BOOL(2);
 	char *nodeNameString = text_to_cstring(nodeName);
 	char *nodeDeleteCommand = NULL;
 	bool hasShardPlacements = false;
@@ -120,7 +121,16 @@ master_remove_node(PG_FUNCTION_ARGS)
 	EnsureSuperUser();
 
 	hasShardPlacements = NodeHasActiveShardPlacements(nodeNameString, nodePort);
-	if (hasShardPlacements)
+	if (hasShardPlacements && force)
+	{
+		ereport(NOTICE, (errmsg("Node %s:%d has active shard placements. Some "
+								"queries may fail after this operation. Use "
+								"select master_add_node('%s', %d) to add this "
+								"node back.",
+								nodeNameString, nodePort, nodeNameString,
+								nodePort)));
+	}
+	else if (hasShardPlacements)
 	{
 		ereport(ERROR, (errmsg("you cannot remove a node which has active "
 							   "shard placements")));

src/test/regress/expected/multi_cluster_management.out

@@ -101,6 +101,31 @@ SELECT master_get_active_worker_nodes();
  (localhost,57637)
 (2 rows)
 
+-- try to remove a node with active placements with force = true and see that node is removed
+SELECT master_remove_node('localhost', :worker_2_port, true); 
+NOTICE:  Node localhost:57638 has active shard placements. Some queries may fail after this operation. Use select master_add_node('localhost', 57638) to add this node back.
+ master_remove_node 
+--------------------
+ 
+(1 row)
+
+SELECT master_get_active_worker_nodes();
+ master_get_active_worker_nodes 
+--------------------------------
+ (localhost,57637)
+(1 row)
+
+-- restore the node for next tests
+SELECT master_add_node('localhost', :worker_2_port);
+         master_add_node         
+---------------------------------
+ (4,4,localhost,57638,default,f)
+(1 row)
+
+-- try to remove a node with active placements with force = false and see that node
+-- removal is failed
+SELECT master_remove_node('localhost', :worker_2_port, false); 
+ERROR:  you cannot remove a node which has active shard placements
 -- mark all placements in the candidate node as inactive
 UPDATE pg_dist_shard_placement SET shardstate=3 WHERE nodeport=:worker_2_port;
 SELECT shardid, shardstate, nodename, nodeport FROM pg_dist_shard_placement WHERE nodeport=:worker_2_port;
@@ -133,7 +158,7 @@ SELECT master_get_active_worker_nodes();
 SELECT master_add_node('localhost', :worker_2_port);
          master_add_node         
 ---------------------------------
- (4,4,localhost,57638,default,f)
+ (5,5,localhost,57638,default,f)
 (1 row)
 
 UPDATE pg_dist_shard_placement SET shardstate=1 WHERE nodeport=:worker_2_port;
@@ -149,7 +174,7 @@ UPDATE pg_dist_node SET hasmetadata=true WHERE nodeport=:worker_1_port;
 SELECT master_add_node('localhost', :worker_2_port);
          master_add_node         
 ---------------------------------
- (5,5,localhost,57638,default,f)
+ (6,6,localhost,57638,default,f)
 (1 row)
 
 \c - - - :worker_1_port
@@ -178,7 +203,7 @@ UPDATE pg_dist_node SET hasmetadata=false WHERE nodeport=:worker_1_port;
 SELECT master_add_node('localhost', :worker_2_port);
          master_add_node         
 ---------------------------------
- (6,6,localhost,57638,default,f)
+ (7,7,localhost,57638,default,f)
 (1 row)
 
 \c - - - :worker_1_port
@@ -208,14 +233,14 @@ SELECT
 	master_add_node('localhost', :worker_2_port);
          master_add_node         |         master_add_node         
 ---------------------------------+---------------------------------
- (7,7,localhost,57637,default,f) | (8,8,localhost,57638,default,f)
+ (8,8,localhost,57637,default,f) | (9,9,localhost,57638,default,f)
 (1 row)
 
 SELECT * FROM pg_dist_node ORDER BY nodeid;
  nodeid | groupid | nodename  | nodeport | noderack | hasmetadata 
 --------+---------+-----------+----------+----------+-------------
-      7 |       7 | localhost |    57637 | default  | f
+      8 |       8 | localhost |    57637 | default  | f
-      8 |       8 | localhost |    57638 | default  | f
+      9 |       9 | localhost |    57638 | default  | f
 (2 rows)
 
 -- check that mixed add/remove node commands work fine inside transaction
@@ -227,9 +252,9 @@ SELECT master_remove_node('localhost', :worker_2_port);
 (1 row)
 
 SELECT master_add_node('localhost', :worker_2_port);
-         master_add_node         
+          master_add_node          
----------------------------------
+-----------------------------------
- (9,9,localhost,57638,default,f)
+ (10,10,localhost,57638,default,f)
 (1 row)
 
 SELECT master_remove_node('localhost', :worker_2_port);
@@ -249,7 +274,7 @@ BEGIN;
 SELECT master_add_node('localhost', :worker_2_port);
           master_add_node          
 -----------------------------------
- (10,10,localhost,57638,default,f)
+ (11,11,localhost,57638,default,f)
 (1 row)
 
 SELECT master_remove_node('localhost', :worker_2_port);
@@ -261,7 +286,7 @@ SELECT master_remove_node('localhost', :worker_2_port);
 SELECT master_add_node('localhost', :worker_2_port);
           master_add_node          
 -----------------------------------
- (11,11,localhost,57638,default,f)
+ (12,12,localhost,57638,default,f)
 (1 row)
 
 COMMIT;
@@ -289,13 +314,13 @@ SELECT master_remove_node(nodename, nodeport) FROM pg_dist_node;
 SELECT master_add_node('localhost', :worker_1_port);
           master_add_node          
 -----------------------------------
- (12,12,localhost,57637,default,f)
+ (13,13,localhost,57637,default,f)
 (1 row)
 
 SELECT master_add_node('localhost', :worker_2_port);
           master_add_node          
 -----------------------------------
- (13,13,localhost,57638,default,f)
+ (14,14,localhost,57638,default,f)
 (1 row)
 
 -- check that a distributed table can be created after adding a node in a transaction
@@ -309,7 +334,7 @@ BEGIN;
 SELECT master_add_node('localhost', :worker_2_port);
           master_add_node          
 -----------------------------------
- (14,14,localhost,57638,default,f)
+ (15,15,localhost,57638,default,f)
 (1 row)
 
 CREATE TABLE temp(col1 text, col2 int);

src/test/regress/expected/multi_extension.out

@@ -70,6 +70,7 @@ ALTER EXTENSION citus UPDATE TO '6.1-9';
 ALTER EXTENSION citus UPDATE TO '6.1-10';
 ALTER EXTENSION citus UPDATE TO '6.1-11';
 ALTER EXTENSION citus UPDATE TO '6.1-12';
+ALTER EXTENSION citus UPDATE TO '6.1-13';
 -- ensure no objects were created outside pg_catalog
 SELECT COUNT(*)
 FROM pg_depend AS pgd,

src/test/regress/sql/multi_cluster_management.sql

@@ -40,6 +40,17 @@ SELECT shardid, shardstate, nodename, nodeport FROM pg_dist_shard_placement WHER
 SELECT master_remove_node('localhost', :worker_2_port); 
 SELECT master_get_active_worker_nodes();
 
+-- try to remove a node with active placements with force = true and see that node is removed
+SELECT master_remove_node('localhost', :worker_2_port, true); 
+SELECT master_get_active_worker_nodes();
+
+-- restore the node for next tests
+SELECT master_add_node('localhost', :worker_2_port);
+
+-- try to remove a node with active placements with force = false and see that node
+-- removal is failed
+SELECT master_remove_node('localhost', :worker_2_port, false); 
+
 -- mark all placements in the candidate node as inactive
 UPDATE pg_dist_shard_placement SET shardstate=3 WHERE nodeport=:worker_2_port;
 SELECT shardid, shardstate, nodename, nodeport FROM pg_dist_shard_placement WHERE nodeport=:worker_2_port;

src/test/regress/sql/multi_extension.sql

@@ -70,6 +70,7 @@ ALTER EXTENSION citus UPDATE TO '6.1-9';
 ALTER EXTENSION citus UPDATE TO '6.1-10';
 ALTER EXTENSION citus UPDATE TO '6.1-11';
 ALTER EXTENSION citus UPDATE TO '6.1-12';
+ALTER EXTENSION citus UPDATE TO '6.1-13';
 
 -- ensure no objects were created outside pg_catalog
 SELECT COUNT(*)