Fix issue with deleting data node and dropping database

CHANGELOG.md

@@ -8,6 +8,7 @@ accidentally triggering the load of a previous DB version.**
 
 **Bugfixes**
 * #4926 Fix corruption when inserting into compressed chunks
+* #5114 Fix issue with deleting data node and dropping database
 * #5130 Fix CAgg on CAgg variable bucket size validation
 * #5133 Fix CAgg on CAgg using different column order on the original hypertable
 * #5152 Fix adding column with NULL constraint to compressed hypertable

tsl/src/data_node.c

@@ -1841,7 +1841,6 @@ data_node_delete(PG_FUNCTION_ARGS)
 	if (drop_database)
 	{
 		TS_PREVENT_IN_TRANSACTION_BLOCK(true);
-		drop_data_node_database(server);
 	}
 
 	/* close any pending connections */
@@ -1873,6 +1872,9 @@ data_node_delete(PG_FUNCTION_ARGS)
 
 	parsetree = (Node *) &stmt;
 
+	if (drop_database)
+		drop_data_node_database(server);
+
 	/* Make sure event triggers are invoked so that all dropped objects
 	 * are collected during a cascading drop. This ensures all dependent
 	 * objects get cleaned up. */

tsl/test/expected/data_node.out

@@ -2117,6 +2117,10 @@ SELECT * FROM alter_data_node('data_node_1');
  data_node_1 | foo.bar | 8989 | new_db   | t
 (1 row)
 
+DROP TABLE hyper1;
+DROP TABLE hyper2;
+DROP TABLE hyper3;
+DROP TABLE hyper_1dim;
 \set ON_ERROR_STOP 0
 -- test some error cases
 SELECT * FROM alter_data_node(NULL);
@@ -2144,10 +2148,6 @@ SELECT node_name, options FROM timescaledb_information.data_nodes order by node_
  data_node_3 | {host=localhost,port=55432,dbname=db_data_node_3,available=true}
 (3 rows)
 
-DROP TABLE hyper1;
-DROP TABLE hyper2;
-DROP TABLE hyper3;
-DROP TABLE hyper_1dim;
 DROP VIEW chunk_query_data_node;
 -- create new session to clear out connection cache
 \c :TEST_DBNAME :ROLE_CLUSTER_SUPERUSER;

tsl/test/expected/data_node_bootstrap.out

@@ -124,11 +124,6 @@ SELECT * FROM delete_data_node('bootstrap_test', drop_database => true);
 ERROR:  delete_data_node() cannot run inside a transaction block
 ROLLBACK;
 \set ON_ERROR_STOP 1
--- Using the drop_database option when there are active connections to
--- the data node should fail. But any connections in the current
--- session should be cleared when dropping the database. To test that
--- the connection is cleared, first create a connection in the
--- connection cache by inserting some data
 CREATE TABLE conditions (time timestamptz, device int, temp float);
 SELECT create_distributed_hypertable('conditions', 'time', 'device');
 WARNING:  only one data node was assigned to the hypertable
@@ -138,6 +133,73 @@ NOTICE:  adding not-null constraint to column "time"
  (1,public,conditions,t)
 (1 row)
 
+\set ON_ERROR_STOP 0
+-- Should fail because the data node is the last one
+SELECT * FROM delete_data_node('bootstrap_test', drop_database => true);
+ERROR:  insufficient number of data nodes for distributed hypertable "conditions"
+\set ON_ERROR_STOP 1
+-- Add another data node
+SELECT node_name, database, node_created, database_created, extension_created
+FROM add_data_node('bootstrap_test_2', host => 'localhost', database => 'bootstrap_test_2', bootstrap => true);
+    node_name     |     database     | node_created | database_created | extension_created 
+------------------+------------------+--------------+------------------+-------------------
+ bootstrap_test_2 | bootstrap_test_2 | t            | t                | t
+(1 row)
+
+SELECT attach_data_node('bootstrap_test_2', 'conditions');
+NOTICE:  the number of partitions in dimension "device" was increased to 2
+    attach_data_node    
+------------------------
+ (1,1,bootstrap_test_2)
+(1 row)
+
+-- Insert some data into the node
+INSERT INTO conditions VALUES ('2021-12-01 10:30', 2, 20.3);
+\set ON_ERROR_STOP 0
+-- Should fail because the data node still holds data
+SELECT * FROM delete_data_node('bootstrap_test_2', drop_database => true);
+ERROR:  insufficient number of data nodes
+\set ON_ERROR_STOP 1
+-- Data node's database still exists after failure to delete
+SELECT count(*) FROM pg_database WHERE datname = 'bootstrap_test_2';
+ count 
+-------
+     1
+(1 row)
+
+-- Delete the chunks so that we can delete the data node
+SELECT drop_chunks('conditions', older_than => '2022-01-01'::timestamptz);
+                 drop_chunks                 
+---------------------------------------------
+ _timescaledb_internal._dist_hyper_1_1_chunk
+(1 row)
+
+SELECT * FROM delete_data_node('bootstrap_test_2', drop_database => true);
+NOTICE:  the number of partitions in dimension "device" of hypertable "conditions" was decreased to 1
+ delete_data_node 
+------------------
+ t
+(1 row)
+
+-- The data node's database is dropped
+SELECT count(*) FROM pg_database WHERE datname = 'bootstrap_test_2';
+ count 
+-------
+     0
+(1 row)
+
+SELECT data_nodes FROM timescaledb_information.hypertables
+WHERE hypertable_name = 'conditions';
+    data_nodes    
+------------------
+ {bootstrap_test}
+(1 row)
+
+-- Using the drop_database option when there are active connections to
+-- the data node should fail. But any connections in the current
+-- session should be cleared when dropping the database. To test that
+-- the connection is cleared, first create a connection in the
+-- connection cache by inserting some data
 INSERT INTO conditions VALUES ('2021-12-01 10:30', 1, 20.3);
 DROP TABLE conditions;
 -- Now drop the data node and it should clear the connection from the

tsl/test/sql/data_node.sql

@@ -978,6 +978,11 @@ SELECT node_name, options FROM timescaledb_information.data_nodes order by node_
 -- just show current options:
 SELECT * FROM alter_data_node('data_node_1');
 
+DROP TABLE hyper1;
+DROP TABLE hyper2;
+DROP TABLE hyper3;
+DROP TABLE hyper_1dim;
+
 \set ON_ERROR_STOP 0
 -- test some error cases
 SELECT * FROM alter_data_node(NULL);
@@ -991,10 +996,6 @@ SELECT delete_data_node('data_node_1', drop_database=>true);
 SELECT * FROM alter_data_node('data_node_1', host=>'localhost', port=>:old_port, database=>:'DN_DBNAME_1');
 SELECT node_name, options FROM timescaledb_information.data_nodes order by node_name;
 
-DROP TABLE hyper1;
-DROP TABLE hyper2;
-DROP TABLE hyper3;
-DROP TABLE hyper_1dim;
 DROP VIEW chunk_query_data_node;
 
 -- create new session to clear out connection cache

tsl/test/sql/data_node_bootstrap.sql

@@ -82,13 +82,46 @@ SELECT * FROM delete_data_node('bootstrap_test', drop_database => true);
 ROLLBACK;
 \set ON_ERROR_STOP 1
 
+CREATE TABLE conditions (time timestamptz, device int, temp float);
+SELECT create_distributed_hypertable('conditions', 'time', 'device');
+
+\set ON_ERROR_STOP 0
+-- Should fail because the data node is the last one
+SELECT * FROM delete_data_node('bootstrap_test', drop_database => true);
+\set ON_ERROR_STOP 1
+
+-- Add another data node
+SELECT node_name, database, node_created, database_created, extension_created
+FROM add_data_node('bootstrap_test_2', host => 'localhost', database => 'bootstrap_test_2', bootstrap => true);
+SELECT attach_data_node('bootstrap_test_2', 'conditions');
+
+-- Insert some data into the node
+INSERT INTO conditions VALUES ('2021-12-01 10:30', 2, 20.3);
+
+\set ON_ERROR_STOP 0
+-- Should fail because the data node still holds data
+SELECT * FROM delete_data_node('bootstrap_test_2', drop_database => true);
+\set ON_ERROR_STOP 1
+
+-- Data node's database still exists after failure to delete
+SELECT count(*) FROM pg_database WHERE datname = 'bootstrap_test_2';
+
+-- Delete the chunks so that we can delete the data node
+SELECT drop_chunks('conditions', older_than => '2022-01-01'::timestamptz);
+
+SELECT * FROM delete_data_node('bootstrap_test_2', drop_database => true);
+
+-- The data node's database is dropped
+SELECT count(*) FROM pg_database WHERE datname = 'bootstrap_test_2';
+
+SELECT data_nodes FROM timescaledb_information.hypertables
+WHERE hypertable_name = 'conditions';
+
 -- Using the drop_database option when there are active connections to
 -- the data node should fail. But any connections in the current
 -- session should be cleared when dropping the database. To test that
 -- the connection is cleared, first create a connection in the
 -- connection cache by inserting some data
-CREATE TABLE conditions (time timestamptz, device int, temp float);
-SELECT create_distributed_hypertable('conditions', 'time', 'device');
 INSERT INTO conditions VALUES ('2021-12-01 10:30', 1, 20.3);
 DROP TABLE conditions;