Adds pg_database_size_local_function

src/backend/distributed/metadata/metadata_sync.c

@@ -17,6 +17,7 @@
 
 #include "postgres.h"
 
+#include "fmgr.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 
@@ -184,6 +185,8 @@ PG_FUNCTION_INFO_V1(citus_internal_add_tenant_schema);
 PG_FUNCTION_INFO_V1(citus_internal_delete_tenant_schema);
 PG_FUNCTION_INFO_V1(citus_internal_update_none_dist_table_metadata);
 PG_FUNCTION_INFO_V1(citus_internal_database_command);
+PG_FUNCTION_INFO_V1(citus_pg_database_size_by_db_name);
+PG_FUNCTION_INFO_V1(citus_pg_database_size_by_db_oid);
 
 
 static bool got_SIGTERM = false;
@@ -4048,6 +4051,43 @@ citus_internal_database_command(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();
 }
 
+Datum
+citus_pg_database_size_by_db_name(PG_FUNCTION_ARGS){
+	CheckCitusVersion(ERROR);
+
+	PG_ENSURE_ARGNOTNULL(0, "dbName");
+
+	Name dbName = PG_GETARG_NAME(0);
+	Datum size = DirectFunctionCall1(pg_database_size_name, NameGetDatum(dbName));
+
+	PG_RETURN_DATUM(size);
+
+}
+
+Datum
+citus_pg_database_size_by_db_oid(PG_FUNCTION_ARGS){
+	CheckCitusVersion(ERROR);
+
+	PG_ENSURE_ARGNOTNULL(0, "dbOid");
+
+	Oid	dbOid = PG_GETARG_OID(0);
+	Datum size = DirectFunctionCall1(pg_database_size_oid, ObjectIdGetDatum(dbOid));
+
+	PG_RETURN_DATUM(size);
+
+}
+
+Datum citus_internal_database_size(PG_FUNCTION_ARGS){
+	CheckCitusVersion(ERROR);
+
+	PG_ENSURE_ARGNOTNULL(0, "dbName");
+
+	Name dbName = PG_GETARG_NAME(0);
+	
+
+	PG_RETURN_DATUM(size);
+}
+
 
 /*
  * SyncNewColocationGroup synchronizes a new pg_dist_colocation entry to a worker.

src/backend/distributed/sql/downgrades/citus--12.2-1--12.1-1.sql

@@ -1,5 +1,7 @@
 -- citus--12.2-1--12.1-1
 
 DROP FUNCTION pg_catalog.citus_internal_database_command(text);
+DROP FUNCTION pg_catalog.pg_database_size_local(name);
+DROP FUNCTION pg_catalog.pg_database_size_local(oid);
 
 #include "../udfs/citus_add_rebalance_strategy/10.1-1.sql"

src/backend/distributed/sql/udfs/citus_internal_database_command/12.2-1.sql

@@ -8,3 +8,19 @@ CREATE OR REPLACE FUNCTION pg_catalog.citus_internal_database_command(command te
 AS 'MODULE_PATHNAME', $$citus_internal_database_command$$;
 COMMENT ON FUNCTION pg_catalog.citus_internal_database_command(text) IS
  'run a database command without transaction block restrictions';
+
+CREATE OR REPLACE FUNCTION pg_catalog.pg_database_size_local(db_name name)
+ RETURNS bigint
+ LANGUAGE C
+ VOLATILE
+AS 'MODULE_PATHNAME', $$citus_pg_database_size_by_db_name$$;
+COMMENT ON FUNCTION pg_catalog.pg_database_size_local(name) IS
+ 'calculates the size of a database in bytes by its name in a multi-node cluster';
+
+ CREATE OR REPLACE FUNCTION pg_catalog.pg_database_size_local(db_oid oid)
+ RETURNS bigint
+ LANGUAGE C
+ VOLATILE
+AS 'MODULE_PATHNAME', $$citus_pg_database_size_by_db_oid$$;
+COMMENT ON FUNCTION pg_catalog.pg_database_size_local(oid) IS
+ 'calculates the size of a database in bytes by its oid in a multi-node cluster';

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

@@ -8,3 +8,19 @@ CREATE OR REPLACE FUNCTION pg_catalog.citus_internal_database_command(command te
 AS 'MODULE_PATHNAME', $$citus_internal_database_command$$;
 COMMENT ON FUNCTION pg_catalog.citus_internal_database_command(text) IS
  'run a database command without transaction block restrictions';
+
+ CREATE OR REPLACE FUNCTION pg_catalog.pg_database_size_local(db_name name)
+ RETURNS bigint
+ LANGUAGE C
+ VOLATILE
+AS 'MODULE_PATHNAME', $$citus_pg_database_size_by_db_name$$;
+COMMENT ON FUNCTION pg_catalog.pg_database_size_local(name) IS
+ 'calculates the size of a database in bytes by its name in a multi-node cluster';
+
+ CREATE OR REPLACE FUNCTION pg_catalog.pg_database_size_local(db_oid oid)
+ RETURNS bigint
+ LANGUAGE C
+ VOLATILE
+AS 'MODULE_PATHNAME', $$citus_pg_database_size_by_db_oid$$;
+COMMENT ON FUNCTION pg_catalog.pg_database_size_local(oid) IS
+ 'calculates the size of a database in bytes by its oid in a multi-node cluster';