Drop shards when a distributed table is dropped

After this change, shards and associated metadata are automatically
dropped when running DROP TABLE on a distributed table, which fixes #230.
It also adds schema support for master_apply_delete_command, which
fixes #73.

Dropping the shards happens in the master_drop_all_shards UDF, which is
called from the SQL_DROP trigger. Inside the trigger, the table is no
longer visible and calling master_apply_delete_command directly wouldn't
work and oid <-> name mappings are not available. The
master_drop_all_shards function therefore takes the relation id, schema
name, and table name as parameters, which can be obtained from
pg_event_trigger_dropped_objects() in the SQL_DROP trigger. If the user
calls master_drop_all_shards while the table still exists, the schema
name and table name are ignored.

Author: Marco Slot
Reviewed-By: Andres Freund

src/backend/distributed/citusdb.sql

@@ -148,6 +148,15 @@ CREATE FUNCTION master_append_table_to_shard(bigint, text, text, integer)
 COMMENT ON FUNCTION master_append_table_to_shard(bigint, text, text, integer)
     IS 'append given table to all shard placements and update metadata';
 
+CREATE FUNCTION master_drop_all_shards(logicalrelid regclass,
+                                       schema_name text,
+                                       table_name text)
+    RETURNS integer
+    LANGUAGE C STRICT
+    AS 'MODULE_PATHNAME', $$master_drop_all_shards$$;
+COMMENT ON FUNCTION master_drop_all_shards(regclass, text, text)
+    IS 'drop all shards in a relation and update metadata';
+
 CREATE FUNCTION master_apply_delete_command(text)
     RETURNS integer
     LANGUAGE C STRICT
@@ -322,7 +331,7 @@ CREATE OR REPLACE FUNCTION citusdb_drop_trigger()
 DECLARE v_obj record;
 BEGIN
     FOR v_obj IN SELECT * FROM pg_event_trigger_dropped_objects() LOOP
-        IF v_obj.object_type <> 'table' THEN
+        IF v_obj.object_type NOT IN ('table', 'foreign table') THEN
            CONTINUE;
         END IF;
 
@@ -331,20 +340,11 @@ BEGIN
             CONTINUE;
         END IF;
 
-        -- check if there's shards for the table, error out if so
-        IF EXISTS(SELECT * FROM pg_dist_shard WHERE logicalrelid = v_obj.objid) THEN
-           RAISE EXCEPTION USING
-                 MESSAGE = 'cannot drop distributed table with existing shards',
-                 HINT = $$Delete shards first using: $$ ||
-                        $$SELECT master_apply_delete_command('DELETE FROM $$ ||
-                        v_obj.object_identity || $$')$$;
-        END IF;
+        -- ensure all shards are dropped
+        PERFORM master_drop_all_shards(v_obj.objid, v_obj.schema_name, v_obj.object_name);
 
         -- delete partition entry
         DELETE FROM pg_dist_partition WHERE logicalrelid = v_obj.objid;
-        IF NOT FOUND THEN
-           RAISE EXCEPTION 'could not find previously found pg_dist_partition entry';
-        END IF;
 
     END LOOP;
 END;

src/backend/distributed/master/master_delete_protocol.c

@@ -18,20 +18,25 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 
+#include "access/xact.h"
+#include "catalog/namespace.h"
 #include "catalog/pg_class.h"
 #include "commands/dbcommands.h"
+#include "commands/event_trigger.h"
 #include "distributed/master_metadata_utility.h"
 #include "distributed/master_protocol.h"
 #include "distributed/metadata_cache.h"
 #include "distributed/multi_client_executor.h"
 #include "distributed/multi_physical_planner.h"
 #include "distributed/multi_server_executor.h"
+#include "distributed/pg_dist_shard.h"
 #include "distributed/pg_dist_partition.h"
 #include "distributed/worker_protocol.h"
 #include "optimizer/clauses.h"
 #include "optimizer/predtest.h"
 #include "optimizer/restrictinfo.h"
 #include "optimizer/var.h"
+#include "nodes/makefuncs.h"
 #include "tcop/tcopprot.h"
 #include "utils/builtins.h"
 #include "utils/datum.h"
@@ -45,12 +50,15 @@ static void CheckDeleteCriteria(Node *deleteCriteria);
 static void CheckPartitionColumn(Oid relationId, Node *whereClause);
 static List * ShardsMatchingDeleteCriteria(Oid relationId, List *shardList,
 										   Node *deleteCriteria);
+static int DropShards(Oid relationId, char *schemaName, char *relationName,
+					  List *deletableShardIntervalList);
 static bool ExecuteRemoteCommand(const char *nodeName, uint32 nodePort,
 								 StringInfo queryString);
 
 
 /* exports for SQL callable functions */
 PG_FUNCTION_INFO_V1(master_apply_delete_command);
+PG_FUNCTION_INFO_V1(master_drop_all_shards);
 
 
 /*
@@ -72,10 +80,9 @@ master_apply_delete_command(PG_FUNCTION_ARGS)
 	text *queryText = PG_GETARG_TEXT_P(0);
 	char *queryString = text_to_cstring(queryText);
 	char *relationName = NULL;
-	text *relationNameText = NULL;
+	char *schemaName = NULL;
 	Oid relationId = InvalidOid;
 	List *shardIntervalList = NIL;
-	ListCell *shardIntervalCell = NULL;
 	List *deletableShardIntervalList = NIL;
 	List *queryTreeList = NIL;
 	Query *deleteQuery = NULL;
@@ -83,11 +90,15 @@ master_apply_delete_command(PG_FUNCTION_ARGS)
 	Node *deleteCriteria = NULL;
 	Node *queryTreeNode = NULL;
 	DeleteStmt *deleteStatement = NULL;
-	int32 deleteCriteriaShardCount = 0;
+	int droppedShardCount = 0;
 	LOCKTAG lockTag;
 	bool sessionLock = false;
 	bool dontWait = false;
 	char partitionMethod = 0;
+	bool failOK = false;
+	bool topLevel = true;
+
+	PreventTransactionChain(topLevel, "master_apply_delete_command");
 
 	queryTreeNode = ParseTreeNode(queryString);
 	if (!IsA(queryTreeNode, DeleteStmt))
@@ -97,10 +108,10 @@ master_apply_delete_command(PG_FUNCTION_ARGS)
 	}
 
 	deleteStatement = (DeleteStmt *) queryTreeNode;
-	relationName = deleteStatement->relation->relname;
-	relationNameText = cstring_to_text(relationName);
 
-	relationId = ResolveRelationId(relationNameText);
+	schemaName = deleteStatement->relation->schemaname;
+	relationName = deleteStatement->relation->relname;
+	relationId = RangeVarGetRelid(deleteStatement->relation, NoLock, failOK);
 	CheckDistributedTable(relationId);
 
 	queryTreeList = pg_analyze_and_rewrite(queryTreeNode, queryString, NULL, 0);
@@ -142,6 +153,71 @@ master_apply_delete_command(PG_FUNCTION_ARGS)
 		                                                          deleteCriteria);
 	}
 
+	droppedShardCount = DropShards(relationId, schemaName, relationName,
+								   deletableShardIntervalList);
+
+	PG_RETURN_INT32(droppedShardCount);
+}
+
+
+/*
+ * master_drop_shards attempts to drop all shards for a given relation.
+ * Unlike master_apply_delete_command, this function can be called even
+ * if the table has already been dropped.
+ */
+Datum
+master_drop_all_shards(PG_FUNCTION_ARGS)
+{
+	Oid relationId = PG_GETARG_OID(0);
+	text *schemaNameText = PG_GETARG_TEXT_P(1);
+	text *relationNameText = PG_GETARG_TEXT_P(2);
+
+	char *schemaName = NULL;
+	char *relationName = NULL;
+	bool topLevel = true;
+	List *shardIntervalList = NIL;
+	int droppedShardCount = 0;
+
+	PreventTransactionChain(topLevel, "DROP distributed table");
+
+	relationName = get_rel_name(relationId);
+
+	if (relationName != NULL)
+	{
+		/* ensure proper values are used if the table exists */
+		Oid schemaId = get_rel_namespace(relationId);
+		schemaName = get_namespace_name(schemaId);
+	}
+	else
+	{
+		/* table has been dropped, rely on user-supplied values */
+		schemaName = text_to_cstring(schemaNameText);
+		relationName = text_to_cstring(relationNameText);
+	}
+
+	shardIntervalList = LoadShardIntervalList(relationId);
+	droppedShardCount = DropShards(relationId, schemaName, relationName,
+								   shardIntervalList);
+
+	PG_RETURN_INT32(droppedShardCount);
+}
+
+
+/*
+ * DropShards drops all given shards in a relation. The id, name and schema
+ * for the relation are explicitly provided, since this function may be
+ * called when the table is already dropped.
+ *
+ * We mark shard placements that we couldn't drop as to be deleted later, but
+ * we do delete the shard metadadata.
+ */
+int
+DropShards(Oid relationId, char *schemaName, char *relationName,
+		   List *deletableShardIntervalList)
+{
+	ListCell *shardIntervalCell = NULL;
+	int droppedShardCount = 0;
+
 	foreach(shardIntervalCell, deletableShardIntervalList)
 	{
 		List *shardPlacementList = NIL;
@@ -152,17 +228,25 @@ master_apply_delete_command(PG_FUNCTION_ARGS)
 		ListCell *lingeringPlacementCell = NULL;
 		ShardInterval *shardInterval = (ShardInterval *) lfirst(shardIntervalCell);
 		uint64 shardId = shardInterval->shardId;
+		char *shardAlias = NULL;
 		char *quotedShardName = NULL;
+		StringInfo shardName = makeStringInfo();
+
+		Assert(shardInterval->relationId == relationId);
 
 		/* if shard doesn't have an alias, extend regular table name */
-		char *shardName = LoadShardAlias(relationId, shardId);
-		if (shardName == NULL)
+		shardAlias = LoadShardAlias(relationId, shardId);
+		if (shardAlias == NULL)
 		{
-			shardName = get_rel_name(relationId);
-			AppendShardIdToName(&shardName, shardId);
+			appendStringInfoString(shardName, relationName);
+			AppendShardIdToStringInfo(shardName, shardId);
+		}
+		else
+		{
+			appendStringInfoString(shardName, shardAlias);
 		}
 
-		quotedShardName = quote_qualified_identifier(NULL, shardName);
+		quotedShardName = quote_qualified_identifier(schemaName, shardName->data);
 
 		shardPlacementList = ShardPlacementList(shardId);
 		foreach(shardPlacementCell, shardPlacementList)
@@ -173,12 +257,13 @@ master_apply_delete_command(PG_FUNCTION_ARGS)
 			bool dropSuccessful = false;
 			StringInfo workerDropQuery = makeStringInfo();
 
-			char tableType = get_rel_relkind(relationId);
-			if (tableType == RELKIND_RELATION)
+			char storageType = shardInterval->storageType;
+			if (storageType == SHARD_STORAGE_TABLE)
 			{
 				appendStringInfo(workerDropQuery, DROP_REGULAR_TABLE_COMMAND, quotedShardName);
 			}
-			else if (tableType == RELKIND_FOREIGN_TABLE)
+			else if (storageType == SHARD_STORAGE_COLUMNAR ||
+					 storageType == SHARD_STORAGE_FOREIGN)
 			{
 				appendStringInfo(workerDropQuery, DROP_FOREIGN_TABLE_COMMAND, quotedShardName);
 			}
@@ -219,7 +304,7 @@ master_apply_delete_command(PG_FUNCTION_ARGS)
 									workerName, workerPort);
 
 			ereport(WARNING, (errmsg("could not delete shard \"%s\" on node "
-									 "\"%s:%u\"", shardName, workerName, workerPort),
+									 "\"%s:%u\"", shardName->data, workerName, workerPort),
 							  errdetail("Marking this shard placement for deletion")));
 		}
 
@@ -234,8 +319,9 @@ master_apply_delete_command(PG_FUNCTION_ARGS)
 		RESUME_INTERRUPTS();
     }
 
-	deleteCriteriaShardCount = list_length(deletableShardIntervalList);
-	PG_RETURN_INT32(deleteCriteriaShardCount);
+	droppedShardCount = list_length(deletableShardIntervalList);
+
+	return droppedShardCount;
 }
 
 

src/backend/distributed/master/master_metadata_utility.c

@@ -452,6 +452,10 @@ DeleteShardRow(uint64 shardId)
 	HeapTuple heapTuple = NULL;
 	Form_pg_dist_shard pgDistShardForm = NULL;
 	Oid distributedRelationId = InvalidOid;
+	HeapTuple relationOidTuple = NULL;
+	TupleDesc tupleDescriptor = NULL;
+	Datum tupleValues[1] = { (Datum) NULL };
+	bool tupleNulls[1] = { false };
 
 	pgDistShard = heap_open(DistShardRelationId(), RowExclusiveLock);
 
@@ -478,8 +482,17 @@ DeleteShardRow(uint64 shardId)
 	systable_endscan(scanDescriptor);
 	heap_close(pgDistShard, RowExclusiveLock);
 
-	/* invalidate previous cache entry */
-	CacheInvalidateRelcacheByRelid(distributedRelationId);
+	/*
+	 * Invalidate using a heap tuple containing the relation OID. We avoid calling
+	 * CacheInvalidateRelcacheByRelid here, since that throw an error if the table
+	 * is no longer in the catalog, which is the case when calling this function
+	 * from a DROP TABLE trigger.
+	 */
+	tupleDescriptor = CreateTemplateTupleDesc(1, true);
+	TupleDescInitEntry(tupleDescriptor, (AttrNumber) 1, "relation", OIDOID, -1, 0);
+	tupleValues[0] = ObjectIdGetDatum(distributedRelationId);
+	relationOidTuple = heap_form_tuple(tupleDescriptor, tupleValues, tupleNulls);
+	CacheInvalidateRelcacheByTuple(relationOidTuple);
 }
 
 

src/backend/distributed/relay/relay_event_utility.c

@@ -509,3 +509,15 @@ AppendShardIdToName(char **name, uint64 shardId)
 	(*name) = (char *) repalloc((*name), extendedNameLength);
 	snprintf((*name), extendedNameLength, "%s", extendedName);
 }
+
+
+/*
+ * AppendShardIdToStringInfo appends shardId to the given name, represented
+ * by a StringInfo.
+ */
+void
+AppendShardIdToStringInfo(StringInfo name, uint64 shardId)
+{
+	appendStringInfo(name, "%c" UINT64_FORMAT, SHARD_NAME_SEPARATOR, shardId);
+}
+

src/include/distributed/master_protocol.h

@@ -98,6 +98,7 @@ extern Datum master_get_active_worker_nodes(PG_FUNCTION_ARGS);
 extern Datum master_create_empty_shard(PG_FUNCTION_ARGS);
 extern Datum master_append_table_to_shard(PG_FUNCTION_ARGS);
 extern Datum master_apply_delete_command(PG_FUNCTION_ARGS);
+extern Datum master_drop_all_shards(PG_FUNCTION_ARGS);
 
 /* function declarations for shard creation functionality */
 extern Datum master_create_worker_shards(PG_FUNCTION_ARGS);

src/include/distributed/relay_utility.h

@@ -15,6 +15,7 @@
 #ifndef RELAY_UTILITY_H
 #define RELAY_UTILITY_H
 
+#include "lib/stringinfo.h"
 #include "nodes/nodes.h"
 
 
@@ -42,6 +43,7 @@ typedef enum
 /* Function declarations to extend names in DDL commands */
 extern void RelayEventExtendNames(Node *parseTree, uint64 shardId);
 extern void AppendShardIdToName(char **name, uint64 shardId);
+extern void AppendShardIdToStringInfo(StringInfo name, uint64 shardId);
 
 
 #endif   /* RELAY_UTILITY_H */

src/test/regress/expected/multi_index_statements_0.out

@@ -136,7 +136,7 @@ DEBUG:  applied command on shard 102010 on node localhost:57637
 DEBUG:  applied command on shard 102010 on node localhost:57638
 DEBUG:  applied command on shard 102009 on node localhost:57637
 DEBUG:  applied command on shard 102009 on node localhost:57638
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 DROP INDEX lineitem_partkey_desc_index;
 DEBUG:  applied command on shard 102014 on node localhost:57637
 DEBUG:  applied command on shard 102014 on node localhost:57638
@@ -150,7 +150,7 @@ DEBUG:  applied command on shard 102010 on node localhost:57637
 DEBUG:  applied command on shard 102010 on node localhost:57638
 DEBUG:  applied command on shard 102009 on node localhost:57637
 DEBUG:  applied command on shard 102009 on node localhost:57638
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 DROP INDEX lineitem_partial_index;
 DEBUG:  applied command on shard 102014 on node localhost:57637
 DEBUG:  applied command on shard 102014 on node localhost:57638
@@ -164,7 +164,7 @@ DEBUG:  applied command on shard 102010 on node localhost:57637
 DEBUG:  applied command on shard 102010 on node localhost:57638
 DEBUG:  applied command on shard 102009 on node localhost:57637
 DEBUG:  applied command on shard 102009 on node localhost:57638
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 -- Verify that we handle if exists statements correctly
 DROP INDEX non_existent_index;
 ERROR:  index "non_existent_index" does not exist
@@ -183,7 +183,7 @@ DEBUG:  applied command on shard 102010 on node localhost:57637
 DEBUG:  applied command on shard 102010 on node localhost:57638
 DEBUG:  applied command on shard 102009 on node localhost:57637
 DEBUG:  applied command on shard 102009 on node localhost:57638
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 DROP INDEX lineitem_orderkey_hash_index;
 ERROR:  index "lineitem_orderkey_hash_index" does not exist
 -- Verify that all the indexes are also dropped from the master node

src/test/regress/expected/multi_table_ddl.out

@@ -22,27 +22,29 @@ ERROR:  cannot execute ALTER TABLE command involving partition column
 -- verify that the distribution column can't be dropped
 ALTER TABLE testtableddl DROP COLUMN distributecol;
 ERROR:  cannot execute ALTER TABLE command involving partition column
--- verify that the table cannot be dropped while shards exist
+-- verify that the table cannot be dropped in a transaction block
+BEGIN;
+DROP TABLE testtableddl;
+ERROR:  DROP distributed table cannot run inside a transaction block
+CONTEXT:  SQL statement "SELECT master_drop_all_shards(v_obj.objid, v_obj.schema_name, v_obj.object_name)"
+PL/pgSQL function citusdb_drop_trigger() line 15 at PERFORM
+ROLLBACK;
+-- verify that the table can be dropped
+DROP TABLE testtableddl;
+-- verify that the table can dropped even if shards exist
+CREATE TABLE testtableddl(somecol int, distributecol text NOT NULL);
+SELECT master_create_distributed_table('testtableddl', 'distributecol', 'append');
+ master_create_distributed_table 
+---------------------------------
+ 
+(1 row)
+
 SELECT 1 FROM master_create_empty_shard('testtableddl');
  ?column? 
 ----------
         1
 (1 row)
 
-DROP TABLE testtableddl;
-ERROR:  cannot drop distributed table with existing shards
-HINT:  Delete shards first using: SELECT master_apply_delete_command('DELETE FROM public.testtableddl')
--- not even with cascade
-DROP TABLE testtableddl CASCADE;
-ERROR:  cannot drop distributed table with existing shards
-HINT:  Delete shards first using: SELECT master_apply_delete_command('DELETE FROM public.testtableddl')
--- but it can be dropped after dropping the shards
-SELECT master_apply_delete_command('DELETE FROM testtableddl');
- master_apply_delete_command 
------------------------------
-                           1
-(1 row)
-
 DROP TABLE testtableddl;
 -- ensure no metadata of distributed tables are remaining
 SELECT * FROM pg_dist_partition;

src/test/regress/expected/multi_utilities.out

@@ -65,10 +65,6 @@ EXECUTE sharded_query;
 ------
 (0 rows)
 
--- try to drop table
-DROP TABLE sharded_table;
-ERROR:  cannot drop distributed table with existing shards
-HINT:  Delete shards first using: SELECT master_apply_delete_command('DELETE FROM public.sharded_table')
 -- try to drop shards with where clause
 SELECT master_apply_delete_command('DELETE FROM sharded_table WHERE id > 0');
 ERROR:  cannot delete from distributed table

src/test/regress/input/multi_master_delete_protocol.source

@@ -46,3 +46,8 @@ SELECT master_create_empty_shard('customer_delete_protocol');
 SELECT master_apply_delete_command('DELETE FROM customer_delete_protocol
                                            WHERE c_custkey > 1000');
 SELECT master_apply_delete_command('DELETE FROM customer_delete_protocol');
+
+-- Verify that master_apply_delete_command cannot be called in a transaction block
+BEGIN;
+SELECT master_apply_delete_command('DELETE FROM customer_delete_protocol');
+ROLLBACK;

src/test/regress/output/multi_alter_table_statements.source

@@ -55,8 +55,8 @@ DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
 DEBUG:  rewriting table "lineitem_alter"
-DEBUG:  drop auto-cascades to type pg_temp_17666
-DEBUG:  drop auto-cascades to type pg_temp_17666[]
+DEBUG:  drop auto-cascades to type pg_temp_17675
+DEBUG:  drop auto-cascades to type pg_temp_17675[]
 ALTER TABLE lineitem_alter ADD COLUMN int_column2 INTEGER DEFAULT 2;
 DEBUG:  applied command on shard 103002 on node localhost:57638
 DEBUG:  applied command on shard 103002 on node localhost:57637
@@ -65,8 +65,8 @@ DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
 DEBUG:  rewriting table "lineitem_alter"
-DEBUG:  drop auto-cascades to type pg_temp_17666
-DEBUG:  drop auto-cascades to type pg_temp_17666[]
+DEBUG:  drop auto-cascades to type pg_temp_17675
+DEBUG:  drop auto-cascades to type pg_temp_17675[]
 ALTER TABLE lineitem_alter ADD COLUMN null_column INTEGER;
 DEBUG:  applied command on shard 103002 on node localhost:57638
 DEBUG:  applied command on shard 103002 on node localhost:57637
@@ -359,8 +359,8 @@ DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
 DEBUG:  rewriting table "lineitem_alter"
-DEBUG:  drop auto-cascades to type pg_temp_17666
-DEBUG:  drop auto-cascades to type pg_temp_17666[]
+DEBUG:  drop auto-cascades to type pg_temp_17675
+DEBUG:  drop auto-cascades to type pg_temp_17675[]
 \d lineitem_alter
             Table "public.lineitem_alter"
      Column      |         Type          | Modifiers 
@@ -478,8 +478,8 @@ DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
 DEBUG:  rewriting table "lineitem_alter"
-DEBUG:  drop auto-cascades to type pg_temp_17666
-DEBUG:  drop auto-cascades to type pg_temp_17666[]
+DEBUG:  drop auto-cascades to type pg_temp_17675
+DEBUG:  drop auto-cascades to type pg_temp_17675[]
 ALTER TABLE lineitem_alter DROP COLUMN non_existent_column;
 WARNING:  could not receive query results from localhost:57637
 DETAIL:  Client error: column "non_existent_column" of relation "lineitem_alter_103009" does not exist

src/test/regress/output/multi_alter_table_statements_0.source

@@ -54,10 +54,10 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerTableRewrite(17667)
+DEBUG:  EventTriggerTableRewrite(17676)
 DEBUG:  rewriting table "lineitem_alter"
-DEBUG:  drop auto-cascades to type pg_temp_17667
-DEBUG:  drop auto-cascades to type pg_temp_17667[]
+DEBUG:  drop auto-cascades to type pg_temp_17676
+DEBUG:  drop auto-cascades to type pg_temp_17676[]
 ALTER TABLE lineitem_alter ADD COLUMN int_column2 INTEGER DEFAULT 2;
 DEBUG:  applied command on shard 103002 on node localhost:57638
 DEBUG:  applied command on shard 103002 on node localhost:57637
@@ -65,10 +65,10 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerTableRewrite(17667)
+DEBUG:  EventTriggerTableRewrite(17676)
 DEBUG:  rewriting table "lineitem_alter"
-DEBUG:  drop auto-cascades to type pg_temp_17667
-DEBUG:  drop auto-cascades to type pg_temp_17667[]
+DEBUG:  drop auto-cascades to type pg_temp_17676
+DEBUG:  drop auto-cascades to type pg_temp_17676[]
 ALTER TABLE lineitem_alter ADD COLUMN null_column INTEGER;
 DEBUG:  applied command on shard 103002 on node localhost:57638
 DEBUG:  applied command on shard 103002 on node localhost:57637
@@ -129,7 +129,7 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 -- \stage to verify that default values take effect
 \STAGE lineitem_alter (l_orderkey, l_partkey, l_suppkey, l_linenumber, l_quantity, l_extendedprice, l_discount, l_tax, l_returnflag, l_linestatus, l_shipdate, l_commitdate, l_receiptdate, l_shipinstruct, l_shipmode, l_comment) FROM '@abs_srcdir@/data/lineitem.1.data' with delimiter '|'
 DEBUG:  parse <unnamed>: SELECT * FROM master_get_table_metadata($1::text)
@@ -235,7 +235,7 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 -- \stage should fail because it will try to insert NULLs for a NOT NULL column
 \STAGE lineitem_alter (l_orderkey, l_partkey, l_suppkey, l_linenumber, l_quantity, l_extendedprice, l_discount, l_tax, l_returnflag, l_linestatus, l_shipdate, l_commitdate, l_receiptdate, l_shipinstruct, l_shipmode, l_comment) FROM '@abs_srcdir@/data/lineitem.1.data' with delimiter '|'
 DEBUG:  parse <unnamed>: SELECT * FROM master_get_table_metadata($1::text)
@@ -362,10 +362,10 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerTableRewrite(17667)
+DEBUG:  EventTriggerTableRewrite(17676)
 DEBUG:  rewriting table "lineitem_alter"
-DEBUG:  drop auto-cascades to type pg_temp_17667
-DEBUG:  drop auto-cascades to type pg_temp_17667[]
+DEBUG:  drop auto-cascades to type pg_temp_17676
+DEBUG:  drop auto-cascades to type pg_temp_17676[]
 \d lineitem_alter
             Table "public.lineitem_alter"
      Column      |         Type          | Modifiers 
@@ -419,7 +419,7 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 ALTER TABLE lineitem_alter DROP COLUMN float_column;
 DEBUG:  applied command on shard 103009 on node localhost:57637
 DEBUG:  applied command on shard 103009 on node localhost:57638
@@ -440,7 +440,7 @@ DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
 DEBUG:  drop auto-cascades to default for table lineitem_alter column float_column
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 ALTER TABLE lineitem_alter DROP COLUMN date_column;
 DEBUG:  applied command on shard 103009 on node localhost:57637
 DEBUG:  applied command on shard 103009 on node localhost:57638
@@ -460,7 +460,7 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 -- Verify that IF EXISTS works as expected
 ALTER TABLE non_existent_table ADD COLUMN new_column INTEGER;
 ERROR:  relation "non_existent_table" does not exist
@@ -485,10 +485,10 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerTableRewrite(17667)
+DEBUG:  EventTriggerTableRewrite(17676)
 DEBUG:  rewriting table "lineitem_alter"
-DEBUG:  drop auto-cascades to type pg_temp_17667
-DEBUG:  drop auto-cascades to type pg_temp_17667[]
+DEBUG:  drop auto-cascades to type pg_temp_17676
+DEBUG:  drop auto-cascades to type pg_temp_17676[]
 ALTER TABLE lineitem_alter DROP COLUMN non_existent_column;
 WARNING:  could not receive query results from localhost:57637
 DETAIL:  Client error: column "non_existent_column" of relation "lineitem_alter_103009" does not exist
@@ -532,7 +532,7 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 \d lineitem_alter
             Table "public.lineitem_alter"
      Column      |         Type          | Modifiers 
@@ -623,7 +623,7 @@ DEBUG:  applied command on shard 103001 on node localhost:57637
 DEBUG:  applied command on shard 103001 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57638
 DEBUG:  applied command on shard 103000 on node localhost:57637
-DEBUG:  EventTriggerInvoke 16532
+DEBUG:  EventTriggerInvoke 16541
 \d lineitem_alter
             Table "public.lineitem_alter"
      Column      |         Type          | Modifiers 

src/test/regress/output/multi_master_delete_protocol.source

@@ -86,3 +86,8 @@ SELECT master_apply_delete_command('DELETE FROM customer_delete_protocol');
                            1
 (1 row)
 
+-- Verify that master_apply_delete_command cannot be called in a transaction block
+BEGIN;
+SELECT master_apply_delete_command('DELETE FROM customer_delete_protocol');
+ERROR:  master_apply_delete_command cannot run inside a transaction block
+ROLLBACK;

src/test/regress/sql/multi_table_ddl.sql

@@ -15,15 +15,18 @@ ALTER TABLE testtableddl ALTER COLUMN distributecol TYPE text;
 -- verify that the distribution column can't be dropped
 ALTER TABLE testtableddl DROP COLUMN distributecol;
 
--- verify that the table cannot be dropped while shards exist
-SELECT 1 FROM master_create_empty_shard('testtableddl');
+-- verify that the table cannot be dropped in a transaction block
+BEGIN;
+DROP TABLE testtableddl;
+ROLLBACK;
+
+-- verify that the table can be dropped
 DROP TABLE testtableddl;
 
--- not even with cascade
-DROP TABLE testtableddl CASCADE;
-
--- but it can be dropped after dropping the shards
-SELECT master_apply_delete_command('DELETE FROM testtableddl');
+-- verify that the table can dropped even if shards exist
+CREATE TABLE testtableddl(somecol int, distributecol text NOT NULL);
+SELECT master_create_distributed_table('testtableddl', 'distributecol', 'append');
+SELECT 1 FROM master_create_empty_shard('testtableddl');
 DROP TABLE testtableddl;
 
 -- ensure no metadata of distributed tables are remaining

src/test/regress/sql/multi_utilities.sql

@@ -36,9 +36,6 @@ EXECUTE sharded_query;
 EXECUTE sharded_delete;
 EXECUTE sharded_query;
 
--- try to drop table
-DROP TABLE sharded_table;
-
 -- try to drop shards with where clause
 SELECT master_apply_delete_command('DELETE FROM sharded_table WHERE id > 0');