trusty (7) EXECUTE_DIRECT.7.gz

NAME

       EXECUTE_DIRECT - Launch queries directly to dedicated nodes

SYNOPSIS

       EXECUTE DIRECT ON ( nodename [, ... ] )
           query

DESCRIPTION

           Note
           The following description applies only to Postgres-XC

       EXECUTE DIRECT is a SQL query specially created for Postgres-XC to allow to launch queries directly to
       dedicated nodes determined by a list of nodes
        nodelist.

       Since Postgres-XC 0.9.3, EXECUTE DIRECT is limited to used on 1 node only. Besides, the query sent to
       remote nodes designed by a list of nodename is limited to SELECT queries. The usage of transaction
       queries (BEGIN, COMMIT...), DDL, and DML (INSERT, UPDATE, DELETE) is forbidden to avoid data
       inconsistency among nodes in the cluster. EXECUTE DIRECT usage is also limited to superusers.

       Either Coordinator or Datanode can be selected by its node name.

       EXECUTE DIRECT allows the usage of the following utility commands on remote nodes: CREATE TABLESPACE,
       DROP TABLESPACE.

PARAMETERS

       nodename
           This mandatory clause specifies the node name on where to launch query. When specifying multiple
           nodes, node names have to be separated by a comma.

       query
           This mandatory clause specifies the raw query to launch on specified node list nodelist.

EXAMPLES

       Select some data in a given table tenk1 on remote Datanode named dn1:

           EXECUTE DIRECT ON NODE dn1 'SELECT * FROM tenk1 WHERE col_char = ''foo''';

       Select local timestamp of a remote node named coord2:

           EXECUTE DIRECT ON coord2 'select clock_timestamp()';

       Select list of tables of a remote node named dn50:

           EXECUTE DIRECT ON dn50 'select tablename from pg_tables';

COMPATIBILITY

       EXECUTE DIRECT does not conform to the SQL standards, it is a Postgres-XC specific command.