Re: patch to allow disable of WAL recycling
| От | Jerry Jelinek |
|---|---|
| Тема | Re: patch to allow disable of WAL recycling |
| Дата | |
| Msg-id | CACPQ5FqkC3F9W6X5qnNH_bHBP5z9fpG8vxtZXVob1+h6NZHi=Q@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: patch to allow disable of WAL recycling (Alvaro Herrera <alvherre@2ndquadrant.com>) |
| Ответы |
Re: patch to allow disable of WAL recycling
|
| Список | pgsql-hackers |
On Wed, Mar 6, 2019 at 11:02 AM Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
On 2019-Mar-06, Robert Haas wrote:
> On Wed, Mar 6, 2019 at 12:13 PM Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
> > I want your dictating software.
>
> I'm afraid this is just me and a keyboard, but sadly for me you're not
> the first person to accuse me of producing giant walls of text.
Well, I don't have a problem reading long texts; my problem is that I'm
unable to argue as quickly.
I do buy your argument, though (if reluctantly); in particular I was
worried to offer a parameter (to turn off zero-filling of segments) that
would enable dangerous behavior, but then I realized we also have
fsync=off of which the same thing can be said. So I agree we should
have two GUCs, properly explained, with a warning where appropriate.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
It sounds like everyone is in agreement that I should get rid of the single COW GUC tunable and provide two different tunables instead. I will update the patch to go back to the original name (wal_recycle) for the original WAL recycling behavior. The default value of that will be true to provide the existing behavior. This matches my original proposal from last year. I will add a new tunable (wal_init_zero) which will control the zero-fill behavior for the WAL file. Again, the default value will be true and provide the existing behavior. Both of these could (should) be set to false for a COW filesystem like ZFS.
If anyone objects to this new approach, let me know, otherwise I'll start preparing an updated patch.
Thanks for all of the feedback,
Jerry
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