Re: [HACKERS] Broken O(n^2) avoidance in wal segment recycling. - Mailing list pgsql-hackers

From Michael Paquier
Subject Re: [HACKERS] Broken O(n^2) avoidance in wal segment recycling.
Date
Msg-id CAB7nPqTB3VcKSSrW2Qj59tYYR2H4+n=5pZbdWou+X9iqVNMCag@mail.gmail.com
Whole thread Raw
In response to Re: [HACKERS] Broken O(n^2) avoidance in wal segment recycling.  (Michael Paquier <michael.paquier@gmail.com>)
Responses Re: [HACKERS] Broken O(n^2) avoidance in wal segment recycling.  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
On Fri, Jun 23, 2017 at 3:25 PM, Michael Paquier
<michael.paquier@gmail.com> wrote:
> On Thu, Jun 22, 2017 at 6:10 AM, Andres Freund <andres@anarazel.de> wrote:
>> We've not heard any complaints about this afaik, but it's not something
>> that's easily diagnosable as being a problem.  Therefore I suspect we
>> should fix and backpatch this?
>
> Agreed. I have just poked at this problem and have finished with the
> attached. Logically it is not complicated at the argument values used
> by the callers of RemoveXlogFile() are never updated when scanning
> pg_wal. Surely this patch needs an extra pair of eyes.

Andres has pointed me out offline that a bad copy-paste re-introduced
fb886c15. So it is important to properly track the segment name of the
switch point as well as the the segment from where the recycling
begins. There was as well a second mistake in RemoveOldXlogFiles()
causing unnecessary segments to be kept caused by the same copy-pasto.
-- 
Michael

-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers

Attachment

pgsql-hackers by date:

Previous
From: Dean Rasheed
Date:
Subject: Re: [HACKERS] Multi column range partition table
Next
From: Kuntal Ghosh
Date:
Subject: Re: [HACKERS] Autovacuum launcher occurs error when cancelled by SIGINT