Horton

Re: patch to allow disable of WAL recycling

Andrew Dunstan <andrew.dunstan@2ndquadrant.com>

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From: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Jerry Jelinek <jerry.jelinek@joyent.com>, Michael Paquier <michael@paquier.xyz>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Thomas Munro <thomas.munro@enterprisedb.com>, Andres Freund <andres@anarazel.de>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-03-06T15:55:35Z
Lists: pgsql-hackers 
On 3/6/19 10:38 AM, Robert Haas wrote:
> On Wed, Feb 27, 2019 at 6:12 PM Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
>> I think the idea of it being a generic tunable for assorted behavior
>> changes, rather than specific to WAL recycling, is a good one.  I'm
>> unsure about your proposed name -- maybe "wal_cow_filesystem" is better?
> I *really* dislike this.  For one thing, it means that users don't
> have control over the behaviors individually.  For another, the
> documentation is now quite imprecise about what the option actually
> does, while expecting users to figure out whether those behaviors are
> acceptable or preferable in their environment.  It lists recycling of
> WAL files and zero-filling of those files as examples of behavior
> changes, but it does not say that those are the only changes, or even
> that they are made in all cases.
>

So you want two options, like wal_recycle_files and wal_zero_fill, both
defaulting to true? Is there a reasonably use case for turning one off
without the other?


Alternatively, we could remove the 'for example" wording, which I agree
is unfortunate.


cheers


andrew

-- 
Andrew Dunstan                https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Add wal_recycle and wal_init_zero GUCs.

  2. Add GUC and storage parameter to set the maximum size of GIN pending list.