Re: Improving compressibility of WAL files

Tom Lane wrote:
> "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
>> Greg Smith <gsmith(at)gregsmith(dot)com> wrote:
>>> I thought at one point that the direction this was going toward was to
>>> provide the size of the WAL file as a parameter you can use in the
>>> archive_command:
>
>> Hard to beat for performance. I thought there was some technical
>> snag.
>
> Yeah: the archiver process doesn't have that information available.

Am I being really dim here - why isn't the first record in the WAL file
a fixed-length record containing e.g. txid_start, time_start, txid_end,
time_end, length? Write it once when you start using the file and once
when it's finished.

--
Richard Huxton
Archonet Ltd