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* Wal_keep_size
@ 2025-10-06 19:50 Raj <[email protected]>
2025-10-06 21:38 ` Re: Wal_keep_size Thomas Carroll <[email protected]>
0 siblings, 1 reply; 6+ messages in thread
From: Raj @ 2025-10-06 19:50 UTC (permalink / raw)
To: Pgsql-admin <[email protected]>
Should Wal_keep_size <= max_wal_size ?
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Wal_keep_size
2025-10-06 19:50 Wal_keep_size Raj <[email protected]>
@ 2025-10-06 21:38 ` Thomas Carroll <[email protected]>
2025-10-07 04:52 ` Re: Wal_keep_size Raj <[email protected]>
0 siblings, 1 reply; 6+ messages in thread
From: Thomas Carroll @ 2025-10-06 21:38 UTC (permalink / raw)
To: Pgsql-admin <[email protected]>; Raj <[email protected]>
Hope nobody minds me chipping in here.
The answer is "not necessarily." The names make them seem closely related, but not so much.
max_wal_size is all about checkpoints. When the WAL exceeds this, Postgres will try to run a checkpoint. Under some circumstances it won't, but let's keep it simple for now.
wal_keep_size is all about replication. Replicas need WAL files to stick around for long enough that they can process them. wal_keep_size is a minimum figure.
Tom On Monday, October 6, 2025 at 03:51:17 PM EDT, Raj <[email protected]> wrote:
Should Wal_keep_size <= max_wal_size ?
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Wal_keep_size
2025-10-06 19:50 Wal_keep_size Raj <[email protected]>
2025-10-06 21:38 ` Re: Wal_keep_size Thomas Carroll <[email protected]>
@ 2025-10-07 04:52 ` Raj <[email protected]>
2025-10-07 04:54 ` Re: Wal_keep_size Raj <[email protected]>
2025-10-07 05:28 ` Re: Wal_keep_size Laurenz Albe <[email protected]>
0 siblings, 2 replies; 6+ messages in thread
From: Raj @ 2025-10-07 04:52 UTC (permalink / raw)
To: Thomas Carroll <[email protected]>; +Cc: Pgsql-admin <[email protected]>
If wal_keep_size is more than max_wal_size wouldn't it always trigger
checkpoint ?
On Tue, 7 Oct 2025, 03:08 Thomas Carroll, <[email protected]> wrote:
> Hope nobody minds me chipping in here.
>
> The answer is "not necessarily." The names make them seem closely
> related, but not so much.
>
> max_wal_size is all about *checkpoints*. When the WAL exceeds this,
> Postgres will try to run a checkpoint. Under some circumstances it won't,
> but let's keep it simple for now.
>
> wal_keep_size is all about *replication*. Replicas need WAL files to
> stick around for long enough that they can process them. wal_keep_size is
> a minimum figure.
>
> Tom
> On Monday, October 6, 2025 at 03:51:17 PM EDT, Raj <
> [email protected]> wrote:
>
>
> Should Wal_keep_size <= max_wal_size ?
>
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Wal_keep_size
2025-10-06 19:50 Wal_keep_size Raj <[email protected]>
2025-10-06 21:38 ` Re: Wal_keep_size Thomas Carroll <[email protected]>
2025-10-07 04:52 ` Re: Wal_keep_size Raj <[email protected]>
@ 2025-10-07 04:54 ` Raj <[email protected]>
1 sibling, 0 replies; 6+ messages in thread
From: Raj @ 2025-10-07 04:54 UTC (permalink / raw)
To: Thomas Carroll <[email protected]>; +Cc: Pgsql-admin <[email protected]>
Note archive mode is enabled.
On Tue, 7 Oct 2025, 10:22 Raj, <[email protected]> wrote:
> If wal_keep_size is more than max_wal_size wouldn't it always trigger
> checkpoint ?
>
> On Tue, 7 Oct 2025, 03:08 Thomas Carroll, <[email protected]> wrote:
>
>> Hope nobody minds me chipping in here.
>>
>> The answer is "not necessarily." The names make them seem closely
>> related, but not so much.
>>
>> max_wal_size is all about *checkpoints*. When the WAL exceeds this,
>> Postgres will try to run a checkpoint. Under some circumstances it won't,
>> but let's keep it simple for now.
>>
>> wal_keep_size is all about *replication*. Replicas need WAL files to
>> stick around for long enough that they can process them. wal_keep_size is
>> a minimum figure.
>>
>> Tom
>> On Monday, October 6, 2025 at 03:51:17 PM EDT, Raj <
>> [email protected]> wrote:
>>
>>
>> Should Wal_keep_size <= max_wal_size ?
>>
>
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Wal_keep_size
2025-10-06 19:50 Wal_keep_size Raj <[email protected]>
2025-10-06 21:38 ` Re: Wal_keep_size Thomas Carroll <[email protected]>
2025-10-07 04:52 ` Re: Wal_keep_size Raj <[email protected]>
@ 2025-10-07 05:28 ` Laurenz Albe <[email protected]>
2025-10-12 07:55 ` Re: Wal_keep_size Raj <[email protected]>
1 sibling, 1 reply; 6+ messages in thread
From: Laurenz Albe @ 2025-10-07 05:28 UTC (permalink / raw)
To: Raj <[email protected]>; Thomas Carroll <[email protected]>; +Cc: Pgsql-admin <[email protected]>
On Tue, 2025-10-07 at 10:22 +0530, Raj wrote:
> If wal_keep_size is more than max_wal_size wouldn't it always trigger checkpoint ?
No. "max_wal_size" has no direct connection with the size of WAL (and I
think we should have chosen a different name for that parameter). The
parameter is about the amount of WAL *generated since the latest checkpoint*,
not about the absolute amount of WAL present.
Yours,
Laurenz Albe
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Wal_keep_size
2025-10-06 19:50 Wal_keep_size Raj <[email protected]>
2025-10-06 21:38 ` Re: Wal_keep_size Thomas Carroll <[email protected]>
2025-10-07 04:52 ` Re: Wal_keep_size Raj <[email protected]>
2025-10-07 05:28 ` Re: Wal_keep_size Laurenz Albe <[email protected]>
@ 2025-10-12 07:55 ` Raj <[email protected]>
0 siblings, 0 replies; 6+ messages in thread
From: Raj @ 2025-10-12 07:55 UTC (permalink / raw)
To: Laurenz Albe <[email protected]>; +Cc: Thomas Carroll <[email protected]>; Pgsql-admin <[email protected]>
Thanks for the clarification.
On Tue, 7 Oct 2025 at 10:58, Laurenz Albe <[email protected]> wrote:
> On Tue, 2025-10-07 at 10:22 +0530, Raj wrote:
> > If wal_keep_size is more than max_wal_size wouldn't it always trigger
> checkpoint ?
>
> No. "max_wal_size" has no direct connection with the size of WAL (and I
> think we should have chosen a different name for that parameter). The
> parameter is about the amount of WAL *generated since the latest
> checkpoint*,
> not about the absolute amount of WAL present.
>
> Yours,
> Laurenz Albe
>
^ permalink raw reply [nested|flat] 6+ messages in thread
end of thread, other threads:[~2025-10-12 07:55 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed)
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2025-10-06 19:50 Wal_keep_size Raj <[email protected]>
2025-10-06 21:38 ` Thomas Carroll <[email protected]>
2025-10-07 04:52 ` Raj <[email protected]>
2025-10-07 04:54 ` Raj <[email protected]>
2025-10-07 05:28 ` Laurenz Albe <[email protected]>
2025-10-12 07:55 ` Raj <[email protected]>
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