Re: patch to allow disable of WAL recycling

Tomas,

Thank you again for running all of these tests on your various hardware
configurations. I was not aware of the convention that the commented
example in the config file is expected to match the default value, so I was
actually trying to show what to use if you didn't want the default, but I
am happy to update the patch so the comment matches the default. Beyond
that, I am unsure what the next steps are for this proposal.

Thanks again,
Jerry

On Tue, Sep 4, 2018 at 12:41 PM, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
wrote:

> Hi,
>
> So here is the last set of benchmark results, this time from ext4 on a
> small SATA-based RAID (3 x 7.2k). As before, I'm only attaching PDFs
> with the simple charts, full results are available in the git repository
> [1]. Overall the numbers are rather boring, with almost no difference
> between the two setups.
>
> That being said, I'm not opposed to introducing the GUC. I'm not going
> to pretend my tests represents all possible HW configs and workloads,
> and I have no trouble believing that it may be quite beneficial in some
> cases.
>
> The one comment about the code is that we usually use the actual default
> value in the config sample. But the patch does this:
>
> +#wal_recycle = off # do not recycle WAL files
>
> while the GUC is defined like this:
>
> {
> {"wal_recycle", PGC_SUSET, WAL_SETTINGS,
> gettext_noop("WAL recycling enabled."),
> NULL
> },
> &wal_recycle,
> true,
> NULL, NULL, NULL
> },
>
> So the default is actually "on" which makes the commented-out config
> sample rather confusing.
>
>
> regards
>
> --
> Tomas Vondra http://www.2ndQuadrant.com
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>