postgres_fdw: Allow fetch_size to be set per-table or per-server.

The default fetch size of 100 rows might not be right in every
environment, so allow users to configure it.

Corey Huinker, reviewed by Kyotaro Horiguchi, Andres Freund, and me.

1 files changed, 20 insertions, 7 deletions

diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index 5a829d537a6..a90983cb1e9 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -290,17 +290,30 @@
        be considered shippable to the remote server.
        This option can only be specified for foreign servers, not per-table.
       </para>
+
+      <para>
+       When using the <literal>extensions</literal> option, <emphasis>it is the
+       user's responsibility</> that the listed extensions exist and behave
+       identically on both the local and remote servers.  Otherwise, remote
+       queries may fail or behave unexpectedly.
+      </para>
      </listitem>
     </varlistentry>
 
-   </variablelist>
+    <varlistentry>
+     <term><literal>fetch_size</literal></term>
+     <listitem>
+      <para>
+       This option specifies the number of rows <filename>postgres_fdw</> 
+       should get in each fetch operation. It can be specified for a foreign
+       table or a foreign server. The option specified on a table overrides
+       an option specified for the server.
+       The default is <literal>100</>.
+      </para>
+     </listitem>
+    </varlistentry>
 
-   <para>
-    When using the <literal>extensions</literal> option, <emphasis>it is the
-    user's responsibility</> that the listed extensions exist and behave
-    identically on both the local and remote servers.  Otherwise, remote
-    queries may fail or behave unexpectedly.
-   </para>
+   </variablelist>
 
   </sect3>