Re: xlogdump

Added to TODO:

* Move pgfoundry's xlogdump to /contrib and have it rely more closely
on the WAL backend code

http://archives.postgresql.org/pgsql-hackers/2007-11/msg00035.php

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Gregory Stark wrote:
>
> There's an xlogdump project on pgfoundry. However it suffers from perennial
> bitrot as it has to maintain its own table of xlog record types and code to
> decode each xlog record type.
>
> Earlier I modified xlogdump to generate a CSV loadable data set so I could do
> some basic analysis and see what types of operations are generating the most
> wal traffic. But I found it had bitrotted and needed some attention to bring
> it up to date.
>
> Again now I wanted to repeat that analysis to measure the effect HOT has had
> on WAL traffic. And again now I find it has bitrotted, not least because of
> HOT of course...
>
> I think this module should be rewritten to depend more closely on the Postgres
> source files. What I'm doing now is making an SRF in the style of the
> pageinspect module which will read an arbitrary wal file and generate records
> directly.
>
> This has a big disadvantage compared to the original approach, namely that you
> need a functioning Postgres instance of the same version to dissect wal
> records.
>
> But it also has a big advantage, namely that it will always be in sync. It
> will just use the same RmgrTable to find the rm_name and call the rm_desc
> method to decode the record. The result might not be quite as or dense as the
> rm_desc function is meant for debugging messages. We could address that
> sometime with a new method if we wanted to.
>
> I'm thinking of actually dropping it directly into the pageinspect contrib
> module. It's not quite an exact fit but it doesn't seem to deserve it's own
> contrib module and it's likely to suffer the same bitrot problem if it lives
> in pgfoundry.
>
> Incidentally I would like to call xlog.c:RecordIsValid() which is currently a
> static function. Any objection to exporting it? It doesn't depend on any
> external xlog.c state.
>
> --
> Gregory Stark
> EnterpriseDB http://www.enterprisedb.com
> Ask me about EnterpriseDB's On-Demand Production Tuning
>
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--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com

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