postgres_fdw: Add support for parallel abort.

postgres_fdw aborts remote (sub)transactions opened on remote server(s)
in a local (sub)transaction one by one when the local (sub)transaction
aborts.  This patch allows it to abort the remote (sub)transactions in
parallel to improve performance.  This is enabled by the server option
"parallel_abort".  The default is false.

Etsuro Fujita, reviewed by David Zhang.

Discussion: http://postgr.es/m/CAPmGK15FuPVGx3TGHKShsbPKKtF1y58-ZLcKoxfN-nqLj1dZ%3Dg%40mail.gmail.com

1 files changed, 31 insertions, 16 deletions

diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index d43ea71407f..9e66987cf7f 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -510,12 +510,13 @@ OPTIONS (ADD password_required 'false');
     corresponding remote transactions, and subtransactions are managed by
     creating corresponding remote subtransactions. When multiple remote
     transactions are involved in the current local transaction, by default
-    <filename>postgres_fdw</filename> commits those remote transactions
-    serially when the local transaction is committed. When multiple remote
-    subtransactions are involved in the current local subtransaction, by
-    default <filename>postgres_fdw</filename> commits those remote
-    subtransactions serially when the local subtransaction is committed.
-    Performance can be improved with the following option:
+    <filename>postgres_fdw</filename> commits or aborts those remote
+    transactions serially when the local transaction is committed or aborted.
+    When multiple remote subtransactions are involved in the current local
+    subtransaction, by default <filename>postgres_fdw</filename> commits or
+    aborts those remote subtransactions serially when the local subtransaction
+    is committed or abortd.
+    Performance can be improved with the following options:
    </para>
 
    <variablelist>
@@ -531,24 +532,38 @@ OPTIONS (ADD password_required 'false');
        specified for foreign servers, not per-table. The default is
        <literal>false</literal>.
       </para>
+     </listitem>
+    </varlistentry>
 
+    <varlistentry>
+     <term><literal>parallel_abort</literal> (<type>boolean</type>)</term>
+     <listitem>
       <para>
-       If multiple foreign servers with this option enabled are involved in a
-       local transaction, multiple remote transactions on those foreign
-       servers are committed in parallel across those foreign servers when
-       the local transaction is committed.
-      </para>
-
-      <para>
-       When this option is enabled, a foreign server with many remote
-       transactions may see a negative performance impact when the local
-       transaction is committed.
+       This option controls whether <filename>postgres_fdw</filename> aborts
+       in parallel remote transactions opened on a foreign server in a local
+       transaction when the local transaction is aborted. This setting also
+       applies to remote and local subtransactions. This option can only be
+       specified for foreign servers, not per-table. The default is
+       <literal>false</literal>.
       </para>
      </listitem>
     </varlistentry>
 
    </variablelist>
 
+   <para>
+    If multiple foreign servers with these options enabled are involved in a
+    local transaction, multiple remote transactions on those foreign servers
+    are committed or aborted in parallel across those foreign servers when
+    the local transaction is committed or aborted.
+   </para>
+
+   <para>
+    When these options are enabled, a foreign server with many remote
+    transactions may see a negative performance impact when the local
+    transaction is committed or aborted.
+   </para>
+
   </sect3>
 
   <sect3 id="postgres-fdw-options-updatability">