Stats improvement for Uncompressed Chunks

During the compression autovacuum use to be disabled for uncompressed
chunk and enable after decompression. This leads to postgres
maintainence issue. Let's not disable autovacuum for uncompressed
chunk anymore. Let postgres take care of the stats in its natural way.

Fixes #309

tsl/src/compression/api.c

@@ -240,47 +240,6 @@ compresschunkcxt_init(CompressChunkCxt *cxt, Cache *hcache, Oid hypertable_relid
 	cxt->srcht_chunk = srcchunk;
 }
 
-static void
-disable_autovacuum_on_chunk(Oid chunk_relid)
-{
-	AlterTableCmd at_cmd = {
-		.type = T_AlterTableCmd,
-		.subtype = AT_SetRelOptions,
-		.def = (Node *) list_make1(
-			makeDefElem("autovacuum_enabled", (Node *) makeString("false"), -1)),
-	};
-	ts_alter_table_with_event_trigger(chunk_relid, NULL, list_make1(&at_cmd), false);
-}
-
-/* This function is intended to undo the disabling of autovacuum done when we compressed a chunk.
- * Note that we do not cache the previous value for this (as we don't expect users to toggle this
- * for individual chunks), so we use the hypertable's setting to determine whether to enable this on
- * the decompressed chunk.
- */
-static void
-restore_autovacuum_on_decompress(Oid uncompressed_hypertable_relid, Oid uncompressed_chunk_relid)
-{
-	Relation tablerel = table_open(uncompressed_hypertable_relid, AccessShareLock);
-	bool ht_autovac_enabled =
-		tablerel->rd_options ? ((StdRdOptions *) (tablerel)->rd_options)->autovacuum.enabled : true;
-
-	table_close(tablerel, AccessShareLock);
-	if (ht_autovac_enabled)
-	{
-		AlterTableCmd at_cmd = {
-			.type = T_AlterTableCmd,
-			.subtype = AT_SetRelOptions,
-			.def = (Node *) list_make1(
-				makeDefElem("autovacuum_enabled", (Node *) makeString("true"), -1)),
-		};
-
-		ts_alter_table_with_event_trigger(uncompressed_chunk_relid,
-										  NULL,
-										  list_make1(&at_cmd),
-										  false);
-	}
-}
-
 static Chunk *
 find_chunk_to_merge_into(Hypertable *ht, Chunk *current_chunk)
 {
@@ -415,10 +374,7 @@ compress_chunk_impl(Oid hypertable_relid, Oid chunk_relid)
 	/* acquire locks on src and compress hypertable and src chunk */
 	LockRelationOid(cxt.srcht->main_table_relid, AccessShareLock);
 	LockRelationOid(cxt.compress_ht->main_table_relid, AccessShareLock);
-	LockRelationOid(cxt.srcht_chunk->table_id, ShareLock);
-
-	/* Disabling autovacuum on chunk which should be empty while in compressed state */
-	disable_autovacuum_on_chunk(chunk_relid);
+	LockRelationOid(cxt.srcht_chunk->table_id, ExclusiveLock);
 
 	/* acquire locks on catalog tables to keep till end of txn */
 	LockRelationOid(catalog_get_table_id(ts_catalog_get(), HYPERTABLE_COMPRESSION),
@@ -637,10 +593,6 @@ decompress_chunk_impl(Oid uncompressed_hypertable_relid, Oid uncompressed_chunk_
 	 */
 	LockRelationOid(compressed_chunk->table_id, AccessExclusiveLock);
 	ts_chunk_drop(compressed_chunk, DROP_RESTRICT, -1);
-
-	/* reenable autovacuum if necessary */
-	restore_autovacuum_on_decompress(uncompressed_hypertable_relid, uncompressed_chunk_relid);
-
 	ts_cache_release(hcache);
 	return true;
 }
@@ -738,8 +690,7 @@ decompress_remote_chunk(FunctionCallInfo fcinfo, const Chunk *chunk, bool if_com
  * chunk_relid - non-compressed chunk relid
  * chunk_table - table containing compressed data
  */
-Datum
-tsl_create_compressed_chunk(PG_FUNCTION_ARGS)
+Datum tsl_create_compressed_chunk(PG_FUNCTION_ARGS)
 {
 	Oid chunk_relid = PG_GETARG_OID(0);
 	Oid chunk_table = PG_GETARG_OID(1);
@@ -806,8 +757,7 @@ tsl_create_compressed_chunk(PG_FUNCTION_ARGS)
 	PG_RETURN_OID(chunk_relid);
 }
 
-Datum
-tsl_compress_chunk(PG_FUNCTION_ARGS)
+Datum tsl_compress_chunk(PG_FUNCTION_ARGS)
 {
 	Oid uncompressed_chunk_id = PG_ARGISNULL(0) ? InvalidOid : PG_GETARG_OID(0);
 	bool if_not_compressed = PG_ARGISNULL(1) ? false : PG_GETARG_BOOL(1);
@@ -836,8 +786,7 @@ tsl_compress_chunk(PG_FUNCTION_ARGS)
 	PG_RETURN_OID(uncompressed_chunk_id);
 }
 
-Datum
-tsl_decompress_chunk(PG_FUNCTION_ARGS)
+Datum tsl_decompress_chunk(PG_FUNCTION_ARGS)
 {
 	Oid uncompressed_chunk_id = PG_ARGISNULL(0) ? InvalidOid : PG_GETARG_OID(0);
 	bool if_compressed = PG_ARGISNULL(1) ? false : PG_GETARG_BOOL(1);

tsl/test/expected/compression.out

@@ -1341,9 +1341,9 @@ SELECT relpages, reltuples FROM pg_class WHERE relname = :statchunk;
 
 -- Verify that decompressing the chunk restores autoanalyze to the hypertable's setting
 SELECT reloptions FROM pg_class WHERE relname = :statchunk;
-         reloptions         
-----------------------------
- {autovacuum_enabled=false}
+ reloptions 
+------------
+
 (1 row)
 
 SELECT decompress_chunk(c) FROM show_chunks('stattest') c;
@@ -1353,9 +1353,9 @@ SELECT decompress_chunk(c) FROM show_chunks('stattest') c;
 (1 row)
 
 SELECT reloptions FROM pg_class WHERE relname = :statchunk;
-        reloptions         
----------------------------
- {autovacuum_enabled=true}
+ reloptions 
+------------
+
 (1 row)
 
 SELECT compress_chunk(c) FROM show_chunks('stattest') c;
@@ -1365,9 +1365,9 @@ SELECT compress_chunk(c) FROM show_chunks('stattest') c;
 (1 row)
 
 SELECT reloptions FROM pg_class WHERE relname = :statchunk;
-         reloptions         
-----------------------------
- {autovacuum_enabled=false}
+ reloptions 
+------------
+
 (1 row)
 
 ALTER TABLE stattest SET (autovacuum_enabled = false);

tsl/test/isolation/expected/compression_chunk_race.out

@@ -38,10 +38,10 @@ step s3_unlock_compression:
     SELECT locktype, mode, granted, objid FROM pg_locks WHERE not granted AND (locktype = 'advisory' or relation::regclass::text LIKE '%chunk') ORDER BY relation, locktype, mode, granted;
     SELECT debug_waitpoint_release('compress_chunk_impl_start');
 
-locktype|mode     |granted|     objid
---------+---------+-------+----------
-relation|ShareLock|f      |          
-advisory|ShareLock|f      |3379597659
+locktype|mode         |granted|     objid
+--------+-------------+-------+----------
+relation|ExclusiveLock|f      |          
+advisory|ShareLock    |f      |3379597659
 (2 rows)
 
 debug_waitpoint_release