Add repartition option on detach/delete_data_node

This change adds a new parameter to the detach_data_node and
delete_data_node functions that will allow the user to automatically
shrink their space dimension to match the number of nodes.

sql/ddl_api.sql

@@ -173,7 +173,8 @@ AS '@MODULE_PATHNAME@', 'ts_data_node_add' LANGUAGE C VOLATILE;
 CREATE OR REPLACE FUNCTION delete_data_node(
     node_name              NAME,
     if_exists              BOOLEAN = FALSE,
-    force                  BOOLEAN = FALSE
+    force                  BOOLEAN = FALSE,
+    repartition            BOOLEAN = TRUE
 ) RETURNS BOOLEAN AS '@MODULE_PATHNAME@', 'ts_data_node_delete' LANGUAGE C VOLATILE;
 
 -- Attach a data node to a distributed hypertable
@@ -186,7 +187,12 @@ CREATE OR REPLACE FUNCTION attach_data_node(
 AS '@MODULE_PATHNAME@', 'ts_data_node_attach' LANGUAGE C VOLATILE;
 
 -- Detach a data node from a distributed hypertable. NULL hypertable means it will detach from all distributed hypertables
-CREATE OR REPLACE FUNCTION detach_data_node(node_name NAME, hypertable REGCLASS = NULL, force BOOLEAN = FALSE) RETURNS INTEGER
+CREATE OR REPLACE FUNCTION detach_data_node(
+    node_name              NAME,
+    hypertable             REGCLASS = NULL,
+    force                  BOOLEAN = FALSE,
+    repartition            BOOLEAN = TRUE
+) RETURNS INTEGER
 AS '@MODULE_PATHNAME@', 'ts_data_node_detach' LANGUAGE C VOLATILE;
 
 -- Block new chunk creation on a data node for a distributed hypertable. NULL hypertable means it will block

tsl/src/data_node.c

@@ -809,18 +809,18 @@ data_node_attach(PG_FUNCTION_ARGS)
 
 	num_nodes = list_length(ht->data_nodes) + 1;
 
+	if (num_nodes > MAX_NUM_HYPERTABLE_DATA_NODES)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("max number of data nodes already attached"),
+				 errdetail("The number of data nodes in a hypertable cannot exceed %d",
+						   MAX_NUM_HYPERTABLE_DATA_NODES)));
+
 	/* If there are less slices (partitions) in the space dimension than there
-	 * are data nodesx, we'd like to expand the number of slices to be able to
+	 * are data nodes, we'd like to expand the number of slices to be able to
 	 * make use of the new data node. */
 	if (NULL != dim && num_nodes > dim->fd.num_slices)
 	{
-		if (num_nodes > MAX_NUM_HYPERTABLE_DATA_NODES)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("max number of data nodes already attached"),
-					 errdetail("The number of data nodes in a hypertable cannot exceed %d",
-							   MAX_NUM_HYPERTABLE_DATA_NODES)));
-
 		if (repartition)
 		{
 			ts_dimension_set_number_of_slices(dim, num_nodes & 0xFFFF);
@@ -975,7 +975,7 @@ data_node_detach_validate(const char *node_name, Hypertable *ht, bool force, Ope
 static int
 data_node_modify_hypertable_data_nodes(const char *node_name, List *hypertable_data_nodes,
 									   bool all_hypertables, OperationType op_type,
-									   bool block_chunks, bool force)
+									   bool block_chunks, bool force, bool repartition)
 {
 	Cache *hcache = ts_hypertable_cache_pin();
 	ListCell *lc;
@@ -1028,6 +1028,26 @@ data_node_modify_hypertable_data_nodes(const char *node_name, List *hypertable_d
 			/* delete hypertable mapping */
 			removed +=
 				ts_hypertable_data_node_delete_by_node_name_and_hypertable_id(node_name, ht->fd.id);
+
+			if (repartition)
+			{
+				Dimension *dim = hyperspace_get_closed_dimension(ht->space, 0);
+				int num_nodes = list_length(ht->data_nodes) - 1;
+
+				if (dim != NULL && num_nodes < dim->fd.num_slices && num_nodes > 0)
+				{
+					ts_dimension_set_number_of_slices(dim, num_nodes & 0xFFFF);
+
+					ereport(NOTICE,
+							(errmsg("the number of partitions in dimension \"%s\" was decreased to "
+									"%u",
+									NameStr(dim->fd.column_name),
+									num_nodes),
+							 errdetail(
+								 "To make efficient use of all attached data nodes, the number of "
+								 "space partitions was set to match the number of data nodes.")));
+				}
+			}
 		}
 		else
 		{
@@ -1065,19 +1085,22 @@ data_node_block_hypertable_data_nodes(const char *node_name, List *hypertable_da
 												  all_hypertables,
 												  OP_BLOCK,
 												  block_chunks,
-												  force);
+												  force,
+												  false);
 }
 
 static int
 data_node_detach_hypertable_data_nodes(const char *node_name, List *hypertable_data_nodes,
-									   bool all_hypertables, bool force, OperationType op_type)
+									   bool all_hypertables, bool force, bool repartition,
+									   OperationType op_type)
 {
 	return data_node_modify_hypertable_data_nodes(node_name,
 												  hypertable_data_nodes,
 												  all_hypertables,
 												  op_type,
 												  false,
-												  force);
+												  force,
+												  repartition);
 }
 
 static HypertableDataNode *
@@ -1171,6 +1194,7 @@ data_node_detach(PG_FUNCTION_ARGS)
 	Oid table_id = PG_ARGISNULL(1) ? InvalidOid : PG_GETARG_OID(1);
 	bool all_hypertables = PG_ARGISNULL(1);
 	bool force = PG_ARGISNULL(2) ? InvalidOid : PG_GETARG_OID(2);
+	bool repartition = PG_ARGISNULL(3) ? false : PG_GETARG_BOOL(3);
 	int removed = 0;
 	List *hypertable_data_nodes = NIL;
 	ForeignServer *server = data_node_get_foreign_server(node_name, ACL_USAGE, true, false);
@@ -1197,6 +1221,7 @@ data_node_detach(PG_FUNCTION_ARGS)
 													 hypertable_data_nodes,
 													 all_hypertables,
 													 force,
+													 repartition,
 													 OP_DETACH);
 
 	PG_RETURN_INT32(removed);
@@ -1208,6 +1233,7 @@ data_node_delete(PG_FUNCTION_ARGS)
 	const char *node_name = PG_ARGISNULL(0) ? NULL : PG_GETARG_CSTRING(0);
 	bool if_exists = PG_ARGISNULL(1) ? false : PG_GETARG_BOOL(1);
 	bool force = PG_ARGISNULL(2) ? false : PG_GETARG_BOOL(2);
+	bool repartition = PG_ARGISNULL(3) ? false : PG_GETARG_BOOL(3);
 	List *hypertable_data_nodes = NIL;
 	DropStmt stmt;
 	ObjectAddress address;
@@ -1247,6 +1273,7 @@ data_node_delete(PG_FUNCTION_ARGS)
 										   hypertable_data_nodes,
 										   true,
 										   force,
+										   repartition,
 										   OP_DELETE);
 
 	stmt = (DropStmt){

tsl/test/expected/chunk_api.out

@@ -458,6 +458,7 @@ RESET ROLE;
 TRUNCATE disttable;
 TRUNCATE costtable;
 SELECT * FROM delete_data_node('data_node_1', force => true);
+NOTICE:  the number of partitions in dimension "device" was decreased to 1
  delete_data_node 
 ------------------
  t

tsl/test/expected/data_node.out

@@ -1016,6 +1016,7 @@ ERROR:  table "devices" is not a hypertable
 -- force detach data node to become under-replicated for new data
 SELECT * FROM detach_data_node('data_node_3', 'disttable_2', force => true);
 WARNING:  new data for hypertable "disttable_2" will be under-replicated due to detaching data node "data_node_3"
+NOTICE:  the number of partitions in dimension "device" was decreased to 1
  detach_data_node 
 ------------------
                 1
@@ -1108,6 +1109,7 @@ ORDER BY foreign_table_name;
 
 SELECT * FROM detach_data_node('data_node_2', 'disttable', true);
 WARNING:  new data for hypertable "disttable" will be under-replicated due to detaching data node "data_node_2"
+NOTICE:  the number of partitions in dimension "device" was decreased to 1
  detach_data_node 
 ------------------
                 1

tsl/test/expected/dist_hypertable-11.out

@@ -1909,6 +1909,41 @@ ts_insert_blocker|     7|_timescaledb_internal.insert_blocker
  
 (1 row)
 
+-- Verify that repartitioning works as expected on detach_data_node
+SELECT * FROM detach_data_node('data_node_1', '"Table\\Schema"."Param_Table"', repartition => true);
+NOTICE:  the number of partitions in dimension "__region" was decreased to 2
+ detach_data_node 
+------------------
+                1
+(1 row)
+
+SELECT h.table_name, d.column_name, d.num_slices
+FROM _timescaledb_catalog.hypertable h, _timescaledb_catalog.dimension d
+WHERE h.id = d.hypertable_id
+AND h.table_name = 'Param_Table';
+ table_name  |   column_name    | num_slices 
+-------------+------------------+------------
+ Param_Table | __region         |          2
+ Param_Table | time Col %#^#@$# |           
+(2 rows)
+
+SELECT * FROM detach_data_node('data_node_2', '"Table\\Schema"."Param_Table"', force => true, repartition => false);
+WARNING:  new data for hypertable "Param_Table" will be under-replicated due to detaching data node "data_node_2"
+ detach_data_node 
+------------------
+                1
+(1 row)
+
+SELECT h.table_name, d.column_name, d.num_slices
+FROM _timescaledb_catalog.hypertable h, _timescaledb_catalog.dimension d
+WHERE h.id = d.hypertable_id
+AND h.table_name = 'Param_Table';
+ table_name  |   column_name    | num_slices 
+-------------+------------------+------------
+ Param_Table | __region         |          2
+ Param_Table | time Col %#^#@$# |           
+(2 rows)
+
 -- Test multi-dimensional hypertable. The add_dimension() command
 -- should be propagated to backends.
 CREATE TABLE dimented_table (time timestamptz, column1 int, column2 timestamptz, column3 int);
@@ -1950,7 +1985,7 @@ SELECT * FROM _timescaledb_catalog.dimension;
   2 |             1 | device           | integer                  | f       |          3 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   3 |             2 | time             | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
   5 |             4 | time Col %#^#@$# | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
-  6 |             4 | __region         | text                     | f       |          4 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
+  6 |             4 | __region         | text                     | f       |          2 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   7 |             5 | time             | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
   8 |             5 | column1          | integer                  | f       |          4 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   9 |             5 | column2          | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
@@ -1970,7 +2005,7 @@ SELECT * FROM _timescaledb_catalog.dimension;
   2 |             1 | device           | integer                  | f       |          3 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   3 |             2 | time             | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
   5 |             4 | time Col %#^#@$# | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
-  6 |             4 | __region         | text                     | f       |          4 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
+  6 |             4 | __region         | text                     | f       |          2 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   7 |             5 | time             | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
   8 |             5 | column1          | integer                  | f       |          4 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   9 |             5 | column2          | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 

tsl/test/expected/dist_hypertable-12.out

@@ -1909,6 +1909,41 @@ ts_insert_blocker|     7|_timescaledb_internal.insert_blocker
  
 (1 row)
 
+-- Verify that repartitioning works as expected on detach_data_node
+SELECT * FROM detach_data_node('data_node_1', '"Table\\Schema"."Param_Table"', repartition => true);
+NOTICE:  the number of partitions in dimension "__region" was decreased to 2
+ detach_data_node 
+------------------
+                1
+(1 row)
+
+SELECT h.table_name, d.column_name, d.num_slices
+FROM _timescaledb_catalog.hypertable h, _timescaledb_catalog.dimension d
+WHERE h.id = d.hypertable_id
+AND h.table_name = 'Param_Table';
+ table_name  |   column_name    | num_slices 
+-------------+------------------+------------
+ Param_Table | __region         |          2
+ Param_Table | time Col %#^#@$# |           
+(2 rows)
+
+SELECT * FROM detach_data_node('data_node_2', '"Table\\Schema"."Param_Table"', force => true, repartition => false);
+WARNING:  new data for hypertable "Param_Table" will be under-replicated due to detaching data node "data_node_2"
+ detach_data_node 
+------------------
+                1
+(1 row)
+
+SELECT h.table_name, d.column_name, d.num_slices
+FROM _timescaledb_catalog.hypertable h, _timescaledb_catalog.dimension d
+WHERE h.id = d.hypertable_id
+AND h.table_name = 'Param_Table';
+ table_name  |   column_name    | num_slices 
+-------------+------------------+------------
+ Param_Table | __region         |          2
+ Param_Table | time Col %#^#@$# |           
+(2 rows)
+
 -- Test multi-dimensional hypertable. The add_dimension() command
 -- should be propagated to backends.
 CREATE TABLE dimented_table (time timestamptz, column1 int, column2 timestamptz, column3 int);
@@ -1950,7 +1985,7 @@ SELECT * FROM _timescaledb_catalog.dimension;
   2 |             1 | device           | integer                  | f       |          3 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   3 |             2 | time             | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
   5 |             4 | time Col %#^#@$# | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
-  6 |             4 | __region         | text                     | f       |          4 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
+  6 |             4 | __region         | text                     | f       |          2 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   7 |             5 | time             | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
   8 |             5 | column1          | integer                  | f       |          4 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   9 |             5 | column2          | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
@@ -1970,7 +2005,7 @@ SELECT * FROM _timescaledb_catalog.dimension;
   2 |             1 | device           | integer                  | f       |          3 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   3 |             2 | time             | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
   5 |             4 | time Col %#^#@$# | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
-  6 |             4 | __region         | text                     | f       |          4 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
+  6 |             4 | __region         | text                     | f       |          2 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   7 |             5 | time             | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 
   8 |             5 | column1          | integer                  | f       |          4 | _timescaledb_internal    | get_partition_hash    |                 |                         | 
   9 |             5 | column2          | timestamp with time zone | t       |            |                          |                       |    604800000000 |                         | 

tsl/test/sql/dist_hypertable.sql.in

@@ -571,6 +571,18 @@ SELECT t.tgname, t.tgtype, t.tgfoid::regproc
 FROM pg_trigger t, pg_class c WHERE c.relname = 'Param_Table' AND t.tgrelid = c.oid;
 $$);
 
+-- Verify that repartitioning works as expected on detach_data_node
+SELECT * FROM detach_data_node('data_node_1', '"Table\\Schema"."Param_Table"', repartition => true);
+SELECT h.table_name, d.column_name, d.num_slices
+FROM _timescaledb_catalog.hypertable h, _timescaledb_catalog.dimension d
+WHERE h.id = d.hypertable_id
+AND h.table_name = 'Param_Table';
+SELECT * FROM detach_data_node('data_node_2', '"Table\\Schema"."Param_Table"', force => true, repartition => false);
+SELECT h.table_name, d.column_name, d.num_slices
+FROM _timescaledb_catalog.hypertable h, _timescaledb_catalog.dimension d
+WHERE h.id = d.hypertable_id
+AND h.table_name = 'Param_Table';
+
 -- Test multi-dimensional hypertable. The add_dimension() command
 -- should be propagated to backends.
 CREATE TABLE dimented_table (time timestamptz, column1 int, column2 timestamptz, column3 int);