Handle TRUNCATE without upcall and handle ONLY modifier

This change refactors the handling of TRUNCATE so
that it is performed directly in process utility without
doing an upcall to PL/pgSQL.

It also adds handling for the ONLY modifier to TRUNCATE,
which shouldn't work on a hypertable. TRUNCATE now generates
an error if TRUNCATE ONLY is used on a hypertable.

Author: erimatnor

sql/ddl_internal.sql

@@ -112,26 +112,6 @@ BEGIN
 END
 $BODY$;
 
-
-CREATE OR REPLACE FUNCTION _timescaledb_internal.truncate_hypertable(
-    schema_name     NAME,
-    table_name      NAME,
-    cascade      BOOLEAN = FALSE
-)
-    RETURNS VOID
-    LANGUAGE PLPGSQL VOLATILE
-    SET search_path = '_timescaledb_internal'
-    AS
-$BODY$
-DECLARE
-    hypertable_row _timescaledb_catalog.hypertable;
-    chunk_row _timescaledb_catalog.chunk;
-BEGIN
-    --TODO: should this cascade?
-    PERFORM  _timescaledb_internal.drop_chunks_impl(NULL, table_name, schema_name, cascade, true);
-END
-$BODY$;
-
 --documentation of these function located in chunk_index.h
 CREATE OR REPLACE FUNCTION _timescaledb_internal.chunk_index_clone(chunk_index_oid OID) RETURNS OID
 AS '@MODULE_PATHNAME@', 'chunk_index_clone' LANGUAGE C VOLATILE STRICT;

sql/updates/pre-0.8.0--0.9.0-dev.sql

@@ -39,6 +39,7 @@ DROP FUNCTION _timescaledb_internal.verify_hypertable_indexes(regclass);
 DROP FUNCTION _timescaledb_internal.validate_triggers(regclass);
 DROP FUNCTION _timescaledb_internal.chunk_create_table(int, name);
 DROP FUNCTION _timescaledb_internal.ddl_change_owner(oid, name);
+DROP FUNCTION _timescaledb_internal.truncate_hypertable(name,name,boolean);
 
 -- Remove redundant index
 DROP INDEX _timescaledb_catalog.dimension_slice_dimension_id_range_start_range_end_idx;

src/catalog.c

@@ -110,10 +110,6 @@ const static InternalFunctionDef internal_function_definitions[_MAX_INTERNAL_FUN
 	[DDL_ADD_CHUNK_CONSTRAINT] = {
 		.name = "chunk_constraint_add_table_constraint",
 		.args = 1,
-	},
-	[TRUNCATE_HYPERTABLE] = {
-		.name = "truncate_hypertable",
-		.args = 3
 	}
 };
 

src/catalog.h

@@ -47,7 +47,6 @@ typedef enum CatalogTable
 typedef enum InternalFunction
 {
 	DDL_ADD_CHUNK_CONSTRAINT,
-	TRUNCATE_HYPERTABLE,
 	_MAX_INTERNAL_FUNCTIONS,
 } InternalFunction;
 

src/process_utility.c

@@ -22,6 +22,7 @@
 #include <utils/lsyscache.h>
 #include <utils/syscache.h>
 #include <utils/builtins.h>
+#include <utils/guc.h>
 #include <utils/snapmgr.h>
 #include <parser/parse_utilcmd.h>
 
@@ -50,14 +51,6 @@ static ProcessUtility_hook_type prev_ProcessUtility_hook;
 
 static bool expect_chunk_modification = false;
 
-/* Macros for DDL upcalls to PL/pgSQL */
-
-#define process_truncate_hypertable(hypertable, cascade)				\
-	CatalogInternalCall3(TRUNCATE_HYPERTABLE,							\
-						 NameGetDatum(&(hypertable)->fd.schema_name),	\
-						 NameGetDatum(&(hypertable)->fd.table_name),	\
-						 BoolGetDatum(cascade))
-
 typedef struct ProcessUtilityArgs
 {
 #if PG10
@@ -147,37 +140,6 @@ relation_not_only(RangeVar *rv)
 				 errmsg("ONLY option not supported on hypertable operations")));
 }
 
-/* Truncate a hypertable */
-static void
-process_truncate(Node *parsetree)
-{
-	TruncateStmt *truncatestmt = (TruncateStmt *) parsetree;
-	Cache	   *hcache = hypertable_cache_pin();
-	ListCell   *cell;
-
-	foreach(cell, truncatestmt->relations)
-	{
-		RangeVar   *relation = lfirst(cell);
-		Oid			relid;
-
-		if (NULL == relation)
-			continue;
-
-		relid = RangeVarGetRelid(relation, NoLock, true);
-
-		if (OidIsValid(relid))
-		{
-			Hypertable *ht = hypertable_cache_get_entry(hcache, relid);
-
-			if (ht != NULL)
-			{
-				process_truncate_hypertable(ht, truncatestmt->behavior == DROP_CASCADE);
-			}
-		}
-	}
-	cache_release(hcache);
-}
-
 /* Change the schema of a hypertable */
 static void
 process_alterobjectschema(Node *parsetree)
@@ -358,6 +320,77 @@ process_vacuum(Node *parsetree, ProcessUtilityContext context)
 	return true;
 }
 
+static void
+process_truncate_chunk(Hypertable *ht, Oid chunk_relid, void *arg)
+{
+	TruncateStmt *stmt = arg;
+	ObjectAddress objaddr = {
+		.classId = RelationRelationId,
+		.objectId = chunk_relid,
+	};
+
+	performDeletion(&objaddr, stmt->behavior, 0);
+}
+
+#if PG10
+#define TRUNCATE_RECURSE(rv) \
+	(rv)->inh
+#elif PG96
+#define TRUNCATE_RECURSE(rv) \
+	((rv)->inhOpt == INH_DEFAULT ? SQL_inheritance : ((rv)->inhOpt == INH_YES))
+#endif
+
+/*
+ * Truncate a hypertable.
+ */
+static bool
+process_truncate(ProcessUtilityArgs *args)
+{
+	TruncateStmt *stmt = (TruncateStmt *) args->parsetree;
+	Cache	   *hcache = hypertable_cache_pin();
+	ListCell   *cell;
+
+	/* Call standard process utility first to truncate all tables */
+	prev_ProcessUtility(args);
+
+	/* For all hypertables, we drop the now empty chunks */
+	foreach(cell, stmt->relations)
+	{
+		RangeVar   *rv = lfirst(cell);
+		Oid			relid;
+
+		if (NULL == rv)
+			continue;
+
+		relid = RangeVarGetRelid(rv, NoLock, true);
+
+		if (OidIsValid(relid))
+		{
+			Hypertable *ht = hypertable_cache_get_entry(hcache, relid);
+
+			if (ht != NULL)
+			{
+				if (!TRUNCATE_RECURSE(rv))
+					ereport(ERROR,
+							(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+							 errmsg("cannot truncate only a hypertable"),
+							 errhint("Do not specify the ONLY keyword, or use truncate"
+									 " only on the chunks directly.")));
+
+				/* Delete the metadata */
+				chunk_delete_by_hypertable_id(ht->fd.id);
+
+				/* Drop the chunk tables */
+				foreach_chunk(ht, process_truncate_chunk, stmt);
+			}
+		}
+	}
+
+	cache_release(hcache);
+
+	return true;
+}
+
 static void
 process_drop_table_chunk(Hypertable *ht, Oid chunk_relid, void *arg)
 {
@@ -1628,32 +1661,29 @@ process_create_trigger_end(Node *parsetree)
  * Handle DDL commands before they have been processed by PostgreSQL.
  */
 static bool
-process_ddl_command_start(Node *parsetree,
-						  const char *query_string,
-						  ProcessUtilityContext context,
-						  char *completion_tag)
+process_ddl_command_start(ProcessUtilityArgs *args)
 {
 	bool		handled = false;
 
-	switch (nodeTag(parsetree))
+	switch (nodeTag(args->parsetree))
 	{
-		case T_TruncateStmt:
-			process_truncate(parsetree);
-			break;
 		case T_AlterObjectSchemaStmt:
-			process_alterobjectschema(parsetree);
+			process_alterobjectschema(args->parsetree);
+			break;
+		case T_TruncateStmt:
+			handled = process_truncate(args);
 			break;
 		case T_AlterTableStmt:
-			process_altertable_start(parsetree);
+			process_altertable_start(args->parsetree);
 			break;
 		case T_RenameStmt:
-			process_rename(parsetree);
+			process_rename(args->parsetree);
 			break;
 		case T_IndexStmt:
-			process_index_start(parsetree);
+			process_index_start(args->parsetree);
 			break;
 		case T_CreateTrigStmt:
-			process_create_trigger_start(parsetree);
+			process_create_trigger_start(args->parsetree);
 			break;
 		case T_DropStmt:
 
@@ -1663,19 +1693,19 @@ process_ddl_command_start(Node *parsetree,
 			 * table is dropped, the drop respects CASCADE in the expected
 			 * way.
 			 */
-			process_drop(parsetree);
+			process_drop(args->parsetree);
 			break;
 		case T_CopyStmt:
-			handled = process_copy(parsetree, query_string, completion_tag);
+			handled = process_copy(args->parsetree, args->query_string, args->completion_tag);
 			break;
 		case T_VacuumStmt:
-			handled = process_vacuum(parsetree, context);
+			handled = process_vacuum(args->parsetree, args->context);
 			break;
 		case T_ReindexStmt:
-			handled = process_reindex(parsetree);
+			handled = process_reindex(args->parsetree);
 			break;
 		case T_ClusterStmt:
-			handled = process_cluster_start(parsetree, context);
+			handled = process_cluster_start(args->parsetree, args->context);
 			break;
 		default:
 			break;
@@ -1762,10 +1792,7 @@ timescaledb_ddl_command_start(
 		return;
 	}
 
-	if (!process_ddl_command_start(args.parsetree,
-								   args.query_string,
-								   args.context,
-								   args.completion_tag))
+	if (!process_ddl_command_start(&args))
 		prev_ProcessUtility(&args);
 }
 

test/expected/pg_dump.out

@@ -49,7 +49,7 @@ SELECT count(*)
      AND refobjid = (SELECT oid FROM pg_extension WHERE extname = 'timescaledb');
  count 
 -------
-    95
+    94
 (1 row)
 
 SELECT * FROM test.show_columns('public."two_Partitions"');
@@ -235,7 +235,7 @@ SELECT count(*)
      AND refobjid = (SELECT oid FROM pg_extension WHERE extname = 'timescaledb');
  count 
 -------
-    95
+    94
 (1 row)
 
 --main table and chunk schemas should be the same

test/expected/truncate_hypertable.out renamed to test/expected/truncate.out

@@ -133,9 +133,29 @@ CREATE TRIGGER _test_truncate_after
 TRUNCATE "two_Partitions";
 WARNING:  FIRING trigger when: BEFORE level: STATEMENT op: TRUNCATE cnt: <NULL> trigger_name _test_truncate_before
 WARNING:  FIRING trigger when: AFTER level: STATEMENT op: TRUNCATE cnt: <NULL> trigger_name _test_truncate_after
-ERROR:  cannot drop table _hyper_1_5_chunk because other objects depend on it
+ERROR:  cannot drop table _timescaledb_internal._hyper_1_5_chunk because other objects depend on it
+-- cannot TRUNCATE ONLY a hypertable
+TRUNCATE ONLY "two_Partitions" CASCADE;
+ERROR:  cannot truncate only a hypertable
 \set ON_ERROR_STOP 1
-TRUNCATE "two_Partitions" CASCADE;
+-- create a regular table to make sure we can truncate it in the same call
+CREATE TABLE truncate_normal (color int);
+INSERT INTO truncate_normal VALUES (1);
+SELECT * FROM truncate_normal;
+ color 
+-------
+     1
+(1 row)
+
+SELECT * FROM test.show_subtables('"two_Partitions"');
+                 Child                  | Tablespace 
+----------------------------------------+------------
+ _timescaledb_internal._hyper_1_5_chunk | 
+ _timescaledb_internal._hyper_1_6_chunk | 
+ _timescaledb_internal._hyper_1_7_chunk | 
+(3 rows)
+
+TRUNCATE "two_Partitions", truncate_normal CASCADE;
 WARNING:  FIRING trigger when: BEFORE level: STATEMENT op: TRUNCATE cnt: <NULL> trigger_name _test_truncate_before
 WARNING:  FIRING trigger when: AFTER level: STATEMENT op: TRUNCATE cnt: <NULL> trigger_name _test_truncate_after
 -- should be empty
@@ -149,3 +169,8 @@ SELECT * FROM "two_Partitions";
 ------------+-----------+----------+----------+----------+-------------
 (0 rows)
 
+SELECT * FROM truncate_normal;
+ color 
+-------
+(0 rows)
+

test/sql/CMakeLists.txt

@@ -42,7 +42,7 @@ set(TEST_FILES
   tablespace.sql
   timestamp.sql
   triggers.sql
-  truncate_hypertable.sql
+  truncate.sql
   update.sql
   upsert.sql
   util.sql

test/sql/truncate_hypertable.sql renamed to test/sql/truncate.sql

@@ -53,9 +53,19 @@ CREATE TRIGGER _test_truncate_after
 
 \set ON_ERROR_STOP 0
 TRUNCATE "two_Partitions";
+-- cannot TRUNCATE ONLY a hypertable
+TRUNCATE ONLY "two_Partitions" CASCADE;
 \set ON_ERROR_STOP 1
 
-TRUNCATE "two_Partitions" CASCADE;
+-- create a regular table to make sure we can truncate it in the same call
+CREATE TABLE truncate_normal (color int);
+INSERT INTO truncate_normal VALUES (1);
+SELECT * FROM truncate_normal;
+
+SELECT * FROM test.show_subtables('"two_Partitions"');
+
+TRUNCATE "two_Partitions", truncate_normal CASCADE;
 -- should be empty
 SELECT * FROM test.show_subtables('"two_Partitions"');
 SELECT * FROM "two_Partitions";
+SELECT * FROM truncate_normal;