Use citus_shard_sizes in citus_tables (#7018)

Fixes #7019 

This PR updates citus_tables view to use citus_shard_sizes function,
instead of citus_total_relation_size to improve performance.

src/backend/distributed/metadata/metadata_utility.c

@@ -91,7 +91,8 @@ static bool DistributedTableSizeOnWorker(WorkerNode *workerNode, Oid relationId,
 										 SizeQueryType sizeQueryType, bool failOnError,
 										 uint64 *tableSize);
 static List * ShardIntervalsOnWorkerGroup(WorkerNode *workerNode, Oid relationId);
-static char * GenerateShardStatisticsQueryForShardList(List *shardIntervalList);
+static char * GenerateShardIdNameValuesForShardList(List *shardIntervalList,
+													bool firstValue);
 static char * GenerateSizeQueryForRelationNameList(List *quotedShardNames,
 												   char *sizeFunction);
 static char * GetWorkerPartitionedSizeUDFNameBySizeQueryType(SizeQueryType sizeQueryType);
@@ -104,7 +105,7 @@ static List * OpenConnectionToNodes(List *workerNodeList);
 static void ReceiveShardIdAndSizeResults(List *connectionList,
 										 Tuplestorestate *tupleStore,
 										 TupleDesc tupleDescriptor);
-static void AppendShardSizeQuery(StringInfo selectQuery, ShardInterval *shardInterval);
+static void AppendShardIdNameValues(StringInfo selectQuery, ShardInterval *shardInterval);
 
 static HeapTuple CreateDiskSpaceTuple(TupleDesc tupleDesc, uint64 availableBytes,
 									  uint64 totalBytes);
@@ -916,6 +917,12 @@ static char *
 GenerateAllShardStatisticsQueryForNode(WorkerNode *workerNode, List *citusTableIds)
 {
 	StringInfo allShardStatisticsQuery = makeStringInfo();
+	bool insertedValues = false;
+
+	appendStringInfoString(allShardStatisticsQuery, "SELECT shard_id, ");
+	appendStringInfo(allShardStatisticsQuery, PG_TOTAL_RELATION_SIZE_FUNCTION,
+					 "table_name");
+	appendStringInfoString(allShardStatisticsQuery, " FROM (VALUES ");
 
 	Oid relationId = InvalidOid;
 	foreach_oid(relationId, citusTableIds)
@@ -930,34 +937,49 @@ GenerateAllShardStatisticsQueryForNode(WorkerNode *workerNode, List *citusTableI
 		{
 			List *shardIntervalsOnNode = ShardIntervalsOnWorkerGroup(workerNode,
 																	 relationId);
-			char *shardStatisticsQuery =
+			if (list_length(shardIntervalsOnNode) == 0)
-				GenerateShardStatisticsQueryForShardList(shardIntervalsOnNode);
+			{
-			appendStringInfoString(allShardStatisticsQuery, shardStatisticsQuery);
+				relation_close(relation, AccessShareLock);
+				continue;
+			}
+			char *shardIdNameValues =
+				GenerateShardIdNameValuesForShardList(shardIntervalsOnNode,
+													  !insertedValues);
+			insertedValues = true;
+			appendStringInfoString(allShardStatisticsQuery, shardIdNameValues);
 			relation_close(relation, AccessShareLock);
 		}
 	}
 
-	/* Add a dummy entry so that UNION ALL doesn't complain */
+	if (!insertedValues)
-	appendStringInfo(allShardStatisticsQuery, "SELECT 0::bigint, 0::bigint;");
+	{
+		return "SELECT 0 AS shard_id, '' AS table_name LIMIT 0";
+	}
 
+	appendStringInfoString(allShardStatisticsQuery, ") t(shard_id, table_name) "
+													"WHERE to_regclass(table_name) IS NOT NULL");
 	return allShardStatisticsQuery->data;
 }
 
 
 /*
- * GenerateShardStatisticsQueryForShardList generates a query that returns:
+ * GenerateShardIdNameValuesForShardList generates a list of (shard_id, shard_name) values
- * SELECT shard_id, shard_name, shard_size for all shards in the list
+ * for all shards in the list
  */
 static char *
-GenerateShardStatisticsQueryForShardList(List *shardIntervalList)
+GenerateShardIdNameValuesForShardList(List *shardIntervalList, bool firstValue)
 {
 	StringInfo selectQuery = makeStringInfo();
 
 	ShardInterval *shardInterval = NULL;
 	foreach_ptr(shardInterval, shardIntervalList)
 	{
-		AppendShardSizeQuery(selectQuery, shardInterval);
+		if (!firstValue)
-		appendStringInfo(selectQuery, " UNION ALL ");
+		{
+			appendStringInfoString(selectQuery, ", ");
+		}
+		firstValue = false;
+		AppendShardIdNameValues(selectQuery, shardInterval);
 	}
 
 	return selectQuery->data;
@@ -965,11 +987,10 @@ GenerateShardStatisticsQueryForShardList(List *shardIntervalList)
 
 
 /*
- * AppendShardSizeQuery appends a query in the following form to selectQuery
+ * AppendShardIdNameValues appends (shard_id, shard_name) for shard
- * SELECT shard_id, shard_name, shard_size
  */
 static void
-AppendShardSizeQuery(StringInfo selectQuery, ShardInterval *shardInterval)
+AppendShardIdNameValues(StringInfo selectQuery, ShardInterval *shardInterval)
 {
 	uint64 shardId = shardInterval->shardId;
 	Oid schemaId = get_rel_namespace(shardInterval->relationId);
@@ -981,8 +1002,7 @@ AppendShardSizeQuery(StringInfo selectQuery, ShardInterval *shardInterval)
 	char *shardQualifiedName = quote_qualified_identifier(schemaName, shardName);
 	char *quotedShardName = quote_literal_cstr(shardQualifiedName);
 
-	appendStringInfo(selectQuery, "SELECT " UINT64_FORMAT " AS shard_id, ", shardId);
+	appendStringInfo(selectQuery, "(" UINT64_FORMAT ", %s)", shardId, quotedShardName);
-	appendStringInfo(selectQuery, PG_TOTAL_RELATION_SIZE_FUNCTION, quotedShardName);
 }
 
 

src/backend/distributed/sql/citus--11.3-1--12.0-1.sql

@@ -25,6 +25,8 @@ GRANT SELECT ON pg_catalog.pg_dist_schema TO public;
 #include "udfs/citus_drop_trigger/12.0-1.sql"
 
 DROP VIEW citus_shards;
+DROP VIEW IF EXISTS pg_catalog.citus_tables;
+DROP VIEW IF EXISTS public.citus_tables;
 DROP FUNCTION citus_shard_sizes;
 #include "udfs/citus_shard_sizes/12.0-1.sql"
 

src/backend/distributed/sql/downgrades/citus--12.0-1--11.3-1.sql

@@ -47,6 +47,9 @@ DROP FUNCTION pg_catalog.citus_internal_unregister_tenant_schema_globally(Oid, t
 DROP VIEW IF EXISTS public.citus_schemas;
 DROP VIEW IF EXISTS pg_catalog.citus_schemas;
 
+DROP VIEW IF EXISTS public.citus_tables;
+DROP VIEW IF EXISTS pg_catalog.citus_tables;
+
 DROP VIEW pg_catalog.citus_shards;
 DROP FUNCTION pg_catalog.citus_shard_sizes;
 #include "../udfs/citus_shard_sizes/10.0-1.sql"

src/backend/distributed/sql/udfs/citus_tables/12.0-1.sql

@@ -14,7 +14,7 @@ citus_tables_create_query=$CTCQ$
         END AS citus_table_type,
         coalesce(column_to_column_name(logicalrelid, partkey), '<none>') AS distribution_column,
         colocationid AS colocation_id,
-        pg_size_pretty(citus_total_relation_size(logicalrelid, fail_on_error := false)) AS table_size,
+        pg_size_pretty(table_sizes.table_size) AS table_size,
         (select count(*) from pg_dist_shard where logicalrelid = p.logicalrelid) AS shard_count,
         pg_get_userbyid(relowner) AS table_owner,
         amname AS access_method
@@ -24,6 +24,13 @@ citus_tables_create_query=$CTCQ$
         pg_class c ON (p.logicalrelid = c.oid)
     LEFT JOIN
         pg_am a ON (a.oid = c.relam)
+    JOIN
+        (
+            SELECT ds.logicalrelid AS table_id, SUM(css.size) AS table_size
+            FROM citus_shard_sizes() css, pg_dist_shard ds
+            WHERE css.shard_id = ds.shardid
+            GROUP BY ds.logicalrelid
+        ) table_sizes ON (table_sizes.table_id = p.logicalrelid)
     WHERE
         -- filter out tables owned by extensions
         logicalrelid NOT IN (

src/backend/distributed/sql/udfs/citus_tables/latest.sql

@@ -14,7 +14,7 @@ citus_tables_create_query=$CTCQ$
         END AS citus_table_type,
         coalesce(column_to_column_name(logicalrelid, partkey), '<none>') AS distribution_column,
         colocationid AS colocation_id,
-        pg_size_pretty(citus_total_relation_size(logicalrelid, fail_on_error := false)) AS table_size,
+        pg_size_pretty(table_sizes.table_size) AS table_size,
         (select count(*) from pg_dist_shard where logicalrelid = p.logicalrelid) AS shard_count,
         pg_get_userbyid(relowner) AS table_owner,
         amname AS access_method
@@ -24,6 +24,13 @@ citus_tables_create_query=$CTCQ$
         pg_class c ON (p.logicalrelid = c.oid)
     LEFT JOIN
         pg_am a ON (a.oid = c.relam)
+    JOIN
+        (
+            SELECT ds.logicalrelid AS table_id, SUM(css.size) AS table_size
+            FROM citus_shard_sizes() css, pg_dist_shard ds
+            WHERE css.shard_id = ds.shardid
+            GROUP BY ds.logicalrelid
+        ) table_sizes ON (table_sizes.table_id = p.logicalrelid)
     WHERE
         -- filter out tables owned by extensions
         logicalrelid NOT IN (

src/test/regress/expected/citus_update_table_statistics.out

@@ -64,15 +64,15 @@ SET citus.multi_shard_modify_mode TO sequential;
 SELECT citus_update_table_statistics('test_table_statistics_hash');
 NOTICE:  issuing BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED;SELECT assign_distributed_transaction_id(xx, xx, 'xxxxxxx');
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
-NOTICE:  issuing SELECT 0::bigint, 0::bigint;
+NOTICE:  issuing SELECT 0 AS shard_id, '' AS table_name LIMIT 0
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
 NOTICE:  issuing BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED;SELECT assign_distributed_transaction_id(xx, xx, 'xxxxxxx');
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
-NOTICE:  issuing SELECT 981000 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981000') UNION ALL SELECT 981001 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981001') UNION ALL SELECT 981002 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981002') UNION ALL SELECT 981003 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981003') UNION ALL SELECT 981004 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981004') UNION ALL SELECT 981005 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981005') UNION ALL SELECT 981006 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981006') UNION ALL SELECT 981007 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981007') UNION ALL SELECT 0::bigint, 0::bigint;
+NOTICE:  issuing SELECT shard_id, pg_total_relation_size(table_name) FROM (VALUES (981000, 'public.test_table_statistics_hash_981000'), (981001, 'public.test_table_statistics_hash_981001'), (981002, 'public.test_table_statistics_hash_981002'), (981003, 'public.test_table_statistics_hash_981003'), (981004, 'public.test_table_statistics_hash_981004'), (981005, 'public.test_table_statistics_hash_981005'), (981006, 'public.test_table_statistics_hash_981006'), (981007, 'public.test_table_statistics_hash_981007')) t(shard_id, table_name) WHERE to_regclass(table_name) IS NOT NULL
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
 NOTICE:  issuing BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED;SELECT assign_distributed_transaction_id(xx, xx, 'xxxxxxx');
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
-NOTICE:  issuing SELECT 981000 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981000') UNION ALL SELECT 981001 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981001') UNION ALL SELECT 981002 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981002') UNION ALL SELECT 981003 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981003') UNION ALL SELECT 981004 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981004') UNION ALL SELECT 981005 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981005') UNION ALL SELECT 981006 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981006') UNION ALL SELECT 981007 AS shard_id, pg_total_relation_size('public.test_table_statistics_hash_981007') UNION ALL SELECT 0::bigint, 0::bigint;
+NOTICE:  issuing SELECT shard_id, pg_total_relation_size(table_name) FROM (VALUES (981000, 'public.test_table_statistics_hash_981000'), (981001, 'public.test_table_statistics_hash_981001'), (981002, 'public.test_table_statistics_hash_981002'), (981003, 'public.test_table_statistics_hash_981003'), (981004, 'public.test_table_statistics_hash_981004'), (981005, 'public.test_table_statistics_hash_981005'), (981006, 'public.test_table_statistics_hash_981006'), (981007, 'public.test_table_statistics_hash_981007')) t(shard_id, table_name) WHERE to_regclass(table_name) IS NOT NULL
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
 NOTICE:  issuing COMMIT
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
@@ -158,15 +158,15 @@ SET citus.multi_shard_modify_mode TO sequential;
 SELECT citus_update_table_statistics('test_table_statistics_append');
 NOTICE:  issuing BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED;SELECT assign_distributed_transaction_id(xx, xx, 'xxxxxxx');
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
-NOTICE:  issuing SELECT 0::bigint, 0::bigint;
+NOTICE:  issuing SELECT 0 AS shard_id, '' AS table_name LIMIT 0
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
 NOTICE:  issuing BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED;SELECT assign_distributed_transaction_id(xx, xx, 'xxxxxxx');
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
-NOTICE:  issuing SELECT 981008 AS shard_id, pg_total_relation_size('public.test_table_statistics_append_981008') UNION ALL SELECT 981009 AS shard_id, pg_total_relation_size('public.test_table_statistics_append_981009') UNION ALL SELECT 0::bigint, 0::bigint;
+NOTICE:  issuing SELECT shard_id, pg_total_relation_size(table_name) FROM (VALUES (981008, 'public.test_table_statistics_append_981008'), (981009, 'public.test_table_statistics_append_981009')) t(shard_id, table_name) WHERE to_regclass(table_name) IS NOT NULL
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
 NOTICE:  issuing BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED;SELECT assign_distributed_transaction_id(xx, xx, 'xxxxxxx');
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
-NOTICE:  issuing SELECT 981008 AS shard_id, pg_total_relation_size('public.test_table_statistics_append_981008') UNION ALL SELECT 981009 AS shard_id, pg_total_relation_size('public.test_table_statistics_append_981009') UNION ALL SELECT 0::bigint, 0::bigint;
+NOTICE:  issuing SELECT shard_id, pg_total_relation_size(table_name) FROM (VALUES (981008, 'public.test_table_statistics_append_981008'), (981009, 'public.test_table_statistics_append_981009')) t(shard_id, table_name) WHERE to_regclass(table_name) IS NOT NULL
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx
 NOTICE:  issuing COMMIT
 DETAIL:  on server postgres@localhost:xxxxx connectionId: xxxxxxx