Add support for ALTER COLUMN SET NOT NULL

mkindahl · mkindahl · commit 8caf04c00dc6 · 2024-11-20T11:51:19.000+01:00
Since `SET NOT NULL` will only do a full table scan of the table to
verify that there are no nulls, this should work without having to
modify any data in the table. However, it does not work for chunks
using the `heap` table access method if they are compressed since it
uses a normal table scan, so adding a check for this.
diff --git a/.unreleased/pr_7463 b/.unreleased/pr_7463
@@ -0,0 +1 @@
+Implements: #7463: Support SET NOT NULL on compressed hypertables
diff --git a/src/process_utility.c b/src/process_utility.c
@@ -281,6 +281,7 @@ check_alter_table_allowed_on_ht_with_compression(Hypertable *ht, AlterTableStmt
 			case AT_ReAddStatistics:
 			case AT_SetCompression:
 			case AT_DropNotNull:
+			case AT_SetNotNull:
 #if PG15_GE
 			case AT_SetAccessMethod:
 #endif
@@ -2563,11 +2564,48 @@ process_altertable_validate_constraint_end(Hypertable *ht, AlterTableCmd *cmd)
 	foreach_chunk(ht, validate_hypertable_constraint, cmd);
 }
 
+/*
+ * Validate that SET NOT NULL is ok for this chunk.
+ *
+ * Throws an error if SET NOT NULL on this chunk is not allowed.
+ */
+static void
+validate_set_not_null(Hypertable *ht, Oid chunk_relid, void *arg)
+{
+	Chunk *chunk = ts_chunk_get_by_relid(chunk_relid, true);
+	if (ts_chunk_is_compressed(chunk) && !ts_is_hypercore_am(chunk->amoid))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("operation not supported on compressed chunks not using the "
+						"\"hypercore\" table access method"),
+				 errdetail("Chunk %s.%s is using the heap table access method and has compressed "
+						   "data.",
+						   NameStr(chunk->fd.schema_name),
+						   NameStr(chunk->fd.table_name)),
+				 errhint("Either decompress all chunks of the hypertable or use \"ALTER TABLE "
+						 "%s.%s SET ACCESS METHOD hypercore\" on all chunks to change access "
+						 "method.",
+						 NameStr(chunk->fd.schema_name),
+						 NameStr(chunk->fd.table_name))));
+	}
+}
+
+/*
+ * This function checks that we are not dropping NOT NULL from bad columns and
+ * that all chunks support the modification.
+ */
 static void
-process_altertable_drop_not_null(Hypertable *ht, AlterTableCmd *cmd)
+process_altertable_alter_not_null_start(Hypertable *ht, AlterTableCmd *cmd)
 {
 	int i;
 
+	if (cmd->subtype == AT_SetNotNull)
+		foreach_chunk(ht, validate_set_not_null, cmd);
+
+	if (cmd->subtype != AT_DropNotNull)
+		return;
+
 	for (i = 0; i < ht->space->num_dimensions; i++)
 	{
 		Dimension *dim = &ht->space->dimensions[i];
@@ -3803,9 +3841,10 @@ process_altertable_start_table(ProcessUtilityArgs *args)
 					verify_constraint_hypertable(ht, cmd->def);
 			}
 			break;
+			case AT_SetNotNull:
 			case AT_DropNotNull:
 				if (ht != NULL)
-					process_altertable_drop_not_null(ht, cmd);
+					process_altertable_alter_not_null_start(ht, cmd);
 				break;
 			case AT_AddColumn:
 #if PG16_LT
@@ -4187,6 +4226,8 @@ process_altertable_end_subcmd(Hypertable *ht, Node *parsetree, ObjectAddress *ob
 		case AT_DropCluster:
 			foreach_chunk(ht, process_altertable_chunk, cmd);
 			break;
+		case AT_SetNotNull:
+		case AT_DropNotNull:
 		case AT_SetRelOptions:
 		case AT_ResetRelOptions:
 		case AT_ReplaceRelOptions:
@@ -4213,8 +4254,6 @@ process_altertable_end_subcmd(Hypertable *ht, Node *parsetree, ObjectAddress *ob
 		case AT_SetStorage:
 		case AT_ColumnDefault:
 		case AT_CookedColumnDefault:
-		case AT_SetNotNull:
-		case AT_DropNotNull:
 		case AT_AddOf:
 		case AT_DropOf:
 		case AT_AddIdentity:
@@ -4494,8 +4533,8 @@ process_reassign_owned_start(ProcessUtilityArgs *args)
 			Oid newrole_oid = get_rolespec_oid(stmt->newrole, false);
 			HeapTuple tuple = ts_scanner_fetch_heap_tuple(ti, false, &should_free);
 
-			/* We do not need to check privileges here since ReassignOwnedObjects() will check the
-			 * privileges and error out if they are not correct. */
+			/* We do not need to check privileges here since ReassignOwnedObjects() will check
+			 * the privileges and error out if they are not correct. */
 			ts_bgw_job_update_owner(ti->scanrel, tuple, ts_scanner_get_tupledesc(ti), newrole_oid);
 
 			if (should_free)
@@ -4631,7 +4670,8 @@ process_create_stmt(ProcessUtilityArgs *args)
 				errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				errmsg("hypercore access method not supported on \"%s\"", stmt->relation->relname),
 				errdetail("The hypercore access method is only supported for hypertables."),
-				errhint("It does not make sense to set the default access method for all tables "
+				errhint("It does not make sense to set the default access method for all "
+						"tables "
 						"to \"%s\" since it is only supported for hypertables.",
 						TS_HYPERCORE_TAM_NAME));
 
diff --git a/tsl/src/hypercore/utils.c b/tsl/src/hypercore/utils.c
@@ -12,6 +12,7 @@
 #include <catalog/pg_class.h>
 #include <commands/defrem.h>
 #include <nodes/makefuncs.h>
+#include <postgres_ext.h>
 #include <storage/lmgr.h>
 #include <storage/lockdefs.h>
 #include <utils/builtins.h>
diff --git a/tsl/test/expected/compression_ddl.out b/tsl/test/expected/compression_ddl.out
@@ -2591,4 +2591,28 @@ SELECT count(*) FROM test2 WHERE i IS NULL;
      1
 (1 row)
 
-SET client_min_messages = NOTICE;
+SELECT count(compress_chunk(ch)) FROM show_chunks('test2') ch;
+ count 
+-------
+    28
+(1 row)
+
+SELECT count(*) FROM test2 WHERE i IS NULL;
+ count 
+-------
+     1
+(1 row)
+
+\set ON_ERROR_STOP 0
+ALTER TABLE test2 ALTER COLUMN i SET NOT NULL;
+ERROR:  operation not supported on compressed chunks not using the "hypercore" table access method
+DELETE FROM test2 WHERE i IS NULL;
+SELECT count(*) FROM test2 WHERE i IS NULL;
+ count 
+-------
+     0
+(1 row)
+
+ALTER TABLE test2 ALTER COLUMN i SET NOT NULL;
+ERROR:  operation not supported on compressed chunks not using the "hypercore" table access method
+\set ON_ERROR_STOP 1
diff --git a/tsl/test/expected/compression_errors-16.out b/tsl/test/expected/compression_errors-16.out
@@ -239,7 +239,7 @@ DETAIL:  Cannot drop column that is a hypertable partitioning (space or time) di
 ALTER TABLE foo DROP COLUMN b;
 ERROR:  cannot drop orderby or segmentby column from a hypertable with compression enabled
 ALTER TABLE foo ALTER COLUMN t SET NOT NULL;
-ERROR:  operation not supported on hypertables that have compression enabled
+ERROR:  column "t" of relation "_hyper_10_2_chunk" contains null values
 ALTER TABLE foo RESET (timescaledb.compress);
 ERROR:  compression options cannot be reset
 --can add constraints as long as no data is compressed
diff --git a/tsl/test/expected/hypercore_ddl.out b/tsl/test/expected/hypercore_ddl.out
@@ -39,10 +39,6 @@ select compress_chunk(show_chunks('readings'), hypercore_use_access_method => tr
  _timescaledb_internal._hyper_1_4_chunk
 (4 rows)
 
--- Insert some extra data to get some non-compressed data as well.
-insert into readings (time, location, device, temp, humidity, jdata)
-select t, ceil(random()*10), ceil(random()*30), random()*40, random()*100, '{"a":1,"b":2}'::jsonb
-from generate_series('2022-06-01 00:01:00'::timestamptz, '2022-06-04'::timestamptz, '5m') t;
 select chunk, amname from chunk_info where hypertable = 'readings'::regclass;
                  chunk                  |  amname   
 ----------------------------------------+-----------
@@ -52,10 +48,144 @@ select chunk, amname from chunk_info where hypertable = 'readings'::regclass;
  _timescaledb_internal._hyper_1_4_chunk | hypercore
 (4 rows)
 
--- Pick a chunk to truncate that is not the first chunk. This is
+----------------------------------------------------------------
+-- Test ALTER TABLE .... ALTER COLUMN commands
+-- This should fail since "location" is NOT NULL
+\set ON_ERROR_STOP 0
+insert into readings(time,device,temp,humidity,jdata)
+values ('2024-01-01 00:00:00', 1, 99.0, 99.0, '{"magic": "yes"}'::jsonb);
+ERROR:  null value in column "location" of relation "_hyper_1_9_chunk" violates not-null constraint
+\set ON_ERROR_STOP 1
+-- Test altering column definitions to drop NOT NULL
+alter table readings alter column location drop not null;
+-- This should now work since we allow NULL values
+insert into readings(time,device,temp,humidity,jdata)
+values ('2024-01-01 00:00:00', 1, 99.0, 99.0, '{"magic": "yes"}'::jsonb);
+select count(*) from readings where location is null;
+ count 
+-------
+     1
+(1 row)
+
+select compress_chunk(show_chunks('readings'), hypercore_use_access_method => true);
+NOTICE:  chunk "_hyper_1_1_chunk" is already compressed
+NOTICE:  chunk "_hyper_1_2_chunk" is already compressed
+NOTICE:  chunk "_hyper_1_3_chunk" is already compressed
+NOTICE:  chunk "_hyper_1_4_chunk" is already compressed
+             compress_chunk              
+-----------------------------------------
+ _timescaledb_internal._hyper_1_1_chunk
+ _timescaledb_internal._hyper_1_2_chunk
+ _timescaledb_internal._hyper_1_3_chunk
+ _timescaledb_internal._hyper_1_4_chunk
+ _timescaledb_internal._hyper_1_10_chunk
+(5 rows)
+
+select count(*) from readings where location is null;
+ count 
+-------
+     1
+(1 row)
+
+-- Pick a chunk to play with that is not the first chunk. This is
 -- mostly a precaution to make sure that there is no bias towards the
 -- first chunk and we could just as well pick the first chunk.
 select chunk from show_chunks('readings') x(chunk) limit 1 offset 3 \gset
+-- We should not be able to set the not null before we have removed
+-- the null rows in the table. This works for hypercore-compressed
+-- chunks but not for heap-compressed chunks.
+\set ON_ERROR_STOP 0
+alter table readings alter column location set not null;
+ERROR:  column "location" of relation "_hyper_1_10_chunk" contains null values
+\set ON_ERROR_STOP 1
+delete from readings where location is null;
+select count(*) from readings where location is null;
+ count 
+-------
+     0
+(1 row)
+
+\d readings
+                       Table "public.readings"
+  Column  |           Type           | Collation | Nullable | Default 
+----------+--------------------------+-----------+----------+---------
+ time     | timestamp with time zone |           | not null | 
+ location | integer                  |           |          | 
+ device   | integer                  |           | not null | 
+ temp     | numeric(4,1)             |           |          | 
+ humidity | double precision         |           |          | 
+ jdata    | jsonb                    |           |          | 
+Indexes:
+    "readings_time_key" UNIQUE CONSTRAINT, btree ("time")
+Triggers:
+    ts_insert_blocker BEFORE INSERT ON readings FOR EACH ROW EXECUTE FUNCTION _timescaledb_functions.insert_blocker()
+Number of child tables: 5 (Use \d+ to list them.)
+
+\d :chunk
+            Table "_timescaledb_internal._hyper_1_4_chunk"
+  Column  |           Type           | Collation | Nullable | Default 
+----------+--------------------------+-----------+----------+---------
+ time     | timestamp with time zone |           | not null | 
+ location | integer                  |           |          | 
+ device   | integer                  |           | not null | 
+ temp     | numeric(4,1)             |           |          | 
+ humidity | double precision         |           |          | 
+ jdata    | jsonb                    |           |          | 
+Indexes:
+    "4_4_readings_time_key" UNIQUE CONSTRAINT, btree ("time")
+Check constraints:
+    "constraint_4" CHECK ("time" >= 'Fri Jun 03 17:00:00 2022 PDT'::timestamp with time zone AND "time" < 'Sat Jun 04 17:00:00 2022 PDT'::timestamp with time zone)
+Inherits: readings
+
+alter table readings alter column location set not null;
+\d readings
+                       Table "public.readings"
+  Column  |           Type           | Collation | Nullable | Default 
+----------+--------------------------+-----------+----------+---------
+ time     | timestamp with time zone |           | not null | 
+ location | integer                  |           | not null | 
+ device   | integer                  |           | not null | 
+ temp     | numeric(4,1)             |           |          | 
+ humidity | double precision         |           |          | 
+ jdata    | jsonb                    |           |          | 
+Indexes:
+    "readings_time_key" UNIQUE CONSTRAINT, btree ("time")
+Triggers:
+    ts_insert_blocker BEFORE INSERT ON readings FOR EACH ROW EXECUTE FUNCTION _timescaledb_functions.insert_blocker()
+Number of child tables: 5 (Use \d+ to list them.)
+
+\d :chunk
+            Table "_timescaledb_internal._hyper_1_4_chunk"
+  Column  |           Type           | Collation | Nullable | Default 
+----------+--------------------------+-----------+----------+---------
+ time     | timestamp with time zone |           | not null | 
+ location | integer                  |           | not null | 
+ device   | integer                  |           | not null | 
+ temp     | numeric(4,1)             |           |          | 
+ humidity | double precision         |           |          | 
+ jdata    | jsonb                    |           |          | 
+Indexes:
+    "4_4_readings_time_key" UNIQUE CONSTRAINT, btree ("time")
+Check constraints:
+    "constraint_4" CHECK ("time" >= 'Fri Jun 03 17:00:00 2022 PDT'::timestamp with time zone AND "time" < 'Sat Jun 04 17:00:00 2022 PDT'::timestamp with time zone)
+Inherits: readings
+
+select count(*) from readings where location is null;
+ count 
+-------
+     0
+(1 row)
+
+----------------------------------------------------------------
+-- TRUNCATE test
+-- We keep the truncate test last in the file to avoid having to
+-- re-populate it.
+-- Insert some extra data to get some non-compressed data as
+-- well. This checks that truncate will deal with with write-store
+-- (WS) and read-store (RS)
+insert into readings (time, location, device, temp, humidity, jdata)
+select t, ceil(random()*10), ceil(random()*30), random()*40, random()*100, '{"a":1,"b":2}'::jsonb
+from generate_series('2022-06-01 00:01:00'::timestamptz, '2022-06-04'::timestamptz, '5m') t;
 -- Check that the number of bytes in the table before and after the
 -- truncate.
 --
@@ -68,7 +198,7 @@ select pg_table_size(chunk) as chunk_size,
  where chunk = :'chunk'::regclass;
  chunk_size | compressed_chunk_size 
 ------------+-----------------------
-      40960 |                 57344
+      49152 |                 57344
 (1 row)
 
 truncate :chunk;
@@ -88,7 +218,7 @@ select (select count(*) from readings) tuples,
        (select count(*) from show_chunks('readings')) chunks;
  tuples | chunks 
 --------+--------
-   1560 |      4
+   1560 |      5
 (1 row)
 
 truncate readings;
@@ -99,32 +229,3 @@ select (select count(*) from readings) tuples,
       0 |      0
 (1 row)
 
-\set ON_ERROR_STOP 0
-insert into readings(time,device,temp,humidity,jdata)
-values ('2024-01-01 00:00:00', 1, 99.0, 99.0, '{"magic": "yes"}'::jsonb);
-ERROR:  null value in column "location" of relation "_hyper_1_9_chunk" violates not-null constraint
-\set ON_ERROR_STOP 1
--- Test altering column definitions
-alter table readings
-      alter column location drop not null;
--- This should now work.
-insert into readings(time,device,temp,humidity,jdata)
-values ('2024-01-01 00:00:00', 1, 99.0, 99.0, '{"magic": "yes"}'::jsonb);
-select count(*) from readings where location is null;
- count 
--------
-     1
-(1 row)
-
-select compress_chunk(show_chunks('readings'), hypercore_use_access_method => true);
-             compress_chunk              
------------------------------------------
- _timescaledb_internal._hyper_1_10_chunk
-(1 row)
-
-select count(*) from readings where location is null;
- count 
--------
-     1
-(1 row)
-
diff --git a/tsl/test/sql/compression_ddl.sql b/tsl/test/sql/compression_ddl.sql
@@ -1069,4 +1069,12 @@ SELECT count(compress_chunk(ch)) FROM show_chunks('test2') ch;
 SELECT count(*) FROM test2 WHERE i IS NULL;
 SELECT count(decompress_chunk(ch)) FROM show_chunks('test2') ch;
 SELECT count(*) FROM test2 WHERE i IS NULL;
-SET client_min_messages = NOTICE;
+SELECT count(compress_chunk(ch)) FROM show_chunks('test2') ch;
+SELECT count(*) FROM test2 WHERE i IS NULL;
+
+\set ON_ERROR_STOP 0
+ALTER TABLE test2 ALTER COLUMN i SET NOT NULL;
+DELETE FROM test2 WHERE i IS NULL;
+SELECT count(*) FROM test2 WHERE i IS NULL;
+ALTER TABLE test2 ALTER COLUMN i SET NOT NULL;
+\set ON_ERROR_STOP 1
diff --git a/tsl/test/sql/hypercore_ddl.sql b/tsl/test/sql/hypercore_ddl.sql

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+Implements: #7463: Support SET NOT NULL on compressed hypertables`