<para>

Not all of the requested files will be WAL segment

files; you should also expect requests for files with a suffix of

<literal>.backup</literal> or <literal>.history</literal>. Also be aware that

<literal>.history</literal>. Also be aware that

the base name of the <literal>%p</literal> path will be different from

<literal>%f</literal>; do not expect them to be interchangeable.

</para>

processing would request a file from the WAL archive, reporting failure

if the file was unavailable. For standby processing it is normal for

the next WAL file to be unavailable, so the standby must wait for

it to appear. For files ending in<literal>.backup</literal> or

it to appear. For files ending in

<literal>.history</literal> there is no need to wait, and a non-zero return

code must be returned. A waiting <varname>restore_command</varname> can be

written as a custom script that loops after polling for the existence of