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<refentry id="SQL-EXECUTEDIRECT">
<indexterm zone="sql-executedirect">
<primary>EXECUTE DIRECT</primary>
</indexterm>
<refmeta>
<refentrytitle>EXECUTE DIRECT</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>EXECUTE DIRECT</refname>
<refpurpose>Launch queries directly to dedicated nodes</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
EXECUTE DIRECT ON ( <replaceable class="parameter">nodename</replaceable> [, ... ] )
<replaceable class="parameter">query</replaceable>
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>EXECUTE DIRECT</command> is a SQL command specially created for
<productname>Postgres-XL</productname> to allow launching queries directly
on one of the nodes determined by a list of nodes <replaceable
class="parameter"> nodelist</replaceable>.
</para>
<para>
EXECUTE DIRECT is currenlty limited to be used on 1 node at a time
only.
The usage of transaction queries
(<literal>BEGIN</literal>, <literal>COMMIT</literal>...), DDL, and DML
(<literal>INSERT</literal>, <literal>UPDATE</literal>, <literal>DELETE
</literal>) is forbidden to avoid data inconsistency among nodes
in the cluster. EXECUTE DIRECT usage is also limited to superusers.
</para>
<para>
Either a Coordinator or Datanode can be selected by its node name.
</para>
<para>
<command>EXECUTE DIRECT</> allows the usage of the following utility commands
on remote nodes: <command>CREATE TABLESPACE</>, <command>DROP TABLESPACE</>.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">nodename</replaceable></term>
<listitem>
<para>
This mandatory clause specifies the node name on where to launch
<replaceable class="parameter">query</replaceable>. When specifying
multiple nodes, node names have to be separated by a comma.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">query</replaceable></term>
<listitem>
<para>
This mandatory clause specifies the raw query to launch
on specified node list <replaceable class="parameter">nodelist</replaceable>.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
Select some data in a given table tenk1 on remote Datanode named dn1:
<programlisting>
EXECUTE DIRECT ON NODE dn1 'SELECT * FROM tenk1 WHERE col_char = ''foo''';
</programlisting>
</para>
<para>
Select local timestamp of a remote node named coord2:
<programlisting>
EXECUTE DIRECT ON coord2 'select clock_timestamp()';
</programlisting>
</para>
<para>
Select list of tables of a remote node named dn50:
<programlisting>
EXECUTE DIRECT ON dn50 'select tablename from pg_tables';
</programlisting>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
<command>EXECUTE DIRECT</command> does not conform to the <acronym>
SQL</acronym> standards, it is a Postgres-XL specific command.
</para>
</refsect1>
</refentry>
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