<title>Transaction Management Options</title>

<para>

When multiple remote (sub)transactions are involved in a local

(sub)transaction, by default <filename>postgres_fdw</filename> commits

those remote (sub)transactions one by one when the local (sub)transaction

commits.

As described in the Transaction Management section, in

<filename>postgres_fdw</filename> transactions are managed by creating

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:

</para>

<listitem>

<para>

This option controls whether <filename>postgres_fdw</filename> commits

remote (sub)transactions opened on a foreign server in a local

(sub)transaction in parallel when the local (sub)transaction commits.

This option can only be specified for foreign servers, not per-table.

The default is <literal>false</literal>.

in parallel remote transactions opened on a foreign server in a local

transaction when the local transaction is committed. 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>

<para>

If multiple foreign servers with this option enabled are involved in

a local (sub)transaction, multiple remote (sub)transactions opened on

those foreign servers in the local (sub)transaction are committed in

parallel across those foreign servers when the local (sub)transaction

commits.

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>

For a foreign server with this option enabled, if many remote

(sub)transactions are opened on the foreign server in a local

(sub)transaction, this option might increase the remote server's load

when the local (sub)transaction commits, so be careful when using this

option.

When this option is enabled, a foreign server with many remote

transactions may see a negative performance impact when the local

transaction is committed.

</para>

</listitem>

</varlistentry>