Feedback-ID: id4a34324:Fastmail
Date: Thu, 14 Sep 2023 18:28:56 -0700
From: Andres Freund <andres@anarazel.de>
To: pgsql-hackers@lists.postgresql.org, Euler Taveira <euler@eulerto.com>,
 Andy Fan <zhihui.fan1213@gmail.com>,
 pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Is it possible to change wal_level online
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Hi,=20

On September 14, 2023 6:21:59 AM PDT, Euler Taveira <euler@eulerto=2Ecom> =
wrote:
>On Thu, Sep 14, 2023, at 7:05 AM, Andy Fan wrote:
>> Currently it is complained that wal_level changes require an instance
>> restart,  I'm not familiar with this stuff so far and I didn't get any =
good
>> information from searching the email archive=2E  So I want to gather=20
>> some feedbacks from experts to  see if it is possible and if not, why
>> it would be the key blocker for this=2E  Basically I agree that changin=
g=20
>> the wal_level  online will be a good experience for users=2E=20
>>=20
>
>This topic was already discussed=2E See this thread [1] that was requesti=
ng to
>change the wal_level default value=2E There might be other threads but I =
didn't
>try hard to find them=2E
>
>
>[1] https://www=2Epostgresql=2Eorg/message-id/20200608213215=2Emgk3cctlzv=
fuaqm6%40alap3=2Eanarazel=2Ede

I think it's gotten a bit easier since then, because we now have global ba=
rriers, to implement the waiting that's mentioned in the email=2E

Possibly we should do the switch to logical dynamically, without a dedicat=
ed wal_level=2E Whenever a logical slot exists, automatically increase the =
Wal level, whenever the last slot is dropped, lower it again=2E Plus some w=
aiting to ensure every backend has knows about the new value=2E=20

Regards,

Andres=20

--=20
Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E