From: | Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com> |
---|---|
To: | Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Restricting maximum keep segments by repslots |
Date: | 2017-02-28 04:27:05 |
Message-ID: | 33bcf803-4aa8-27b6-b6bd-4fb3ae950b19@2ndquadrant.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
On 28/02/17 04:27, Kyotaro HORIGUCHI wrote:
> Hello.
>
> Although replication slot is helpful to avoid unwanted WAL
> deletion, on the other hand it can cause a disastrous situation
> by keeping WAL segments without a limit. Removing the causal
> repslot will save this situation but it is not doable if the
> standby is active. We should do a rather complex and forcible
> steps to relieve the situation especially in an automatic
> manner. (As for me, specifically in an HA cluster.)
>
I agree that that it should be possible to limit how much WAL slot keeps.
> This patch adds a GUC to put a limit to the number of segments
> that replication slots can keep. Hitting the limit during
> checkpoint shows a warining and the segments older than the limit
> are removed.
>
>> WARNING: restart LSN of replication slots is ignored by checkpoint
>> DETAIL: Some replication slots lose required WAL segnents to continue.
>
However this is dangerous as logical replication slot does not consider
it error when too old LSN is requested so we'd continue replication,
hiding data loss.
--
Petr Jelinek http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
From | Date | Subject | |
---|---|---|---|
Next Message | 钱新林 | 2017-02-28 04:31:57 | help to identify the reason that extension's C function returns array get segmentation fault |
Previous Message | Kyotaro HORIGUCHI | 2017-02-28 04:19:10 | Re: Radix tree for character conversion |