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Date: Wed, 06 Dec 2023 23:32:19 -0300
From: "Euler Taveira" <euler@eulerto.com>
To: "Michael Paquier" <michael@paquier.xyz>
Cc: "Peter Eisentraut" <peter@eisentraut.org>,
 "Bharath Rupireddy" <bharath.rupireddyforpostgres@gmail.com>,
 "PostgreSQL Hackers" <pgsql-hackers@lists.postgresql.org>
Subject: Re: Is WAL_DEBUG related code still relevant today?
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On Wed, Dec 6, 2023, at 9:51 PM, Michael Paquier wrote:
> PerformWalRecovery() with its log for RM_XACT_ID is something that
> stresses me a bit though because this is in the main redo loop which
> is never free.  The same can be said about GenericXLogFinish() because
> the extra computation happens while holding a buffer and marking it
> dirty.  The ones in xlog.c are free of charge as they are called
> outside any critical portions.
> 
> This makes me wonder how much we need to care about
> trace_recovery_messages, actually, and I've never used it.

IIUC trace_recovery_messages was a debugging aid in the 9.0 era when the HS was
introduced. I'm also wondering if anyone used it in the past years.

elog.c:

* Intention is to keep this for at least the whole of the 9.0 production
* release, so we can more easily diagnose production problems in the field.
* It should go away eventually, though, because it's an ugly and
* hard-to-explain kluge.
*/
int
trace_recovery(int trace_level)
{
    if (trace_level < LOG &&
        trace_level >= trace_recovery_messages)
        return LOG; 

    return trace_level;
}


--
Euler Taveira
EDB   https://www.enterprisedb.com/

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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div>On Wed, Dec 6, =
2023, at 9:51 PM, Michael Paquier wrote:<br></div><blockquote type=3D"ci=
te" id=3D"qt" style=3D""><div>PerformWalRecovery() with its log for RM_X=
ACT_ID is something that<br></div><div>stresses me a bit though because =
this is in the main redo loop which<br></div><div>is never free.&nbsp; T=
he same can be said about GenericXLogFinish() because<br></div><div>the =
extra computation happens while holding a buffer and marking it<br></div=
><div>dirty.&nbsp; The ones in xlog.c are free of charge as they are cal=
led<br></div><div>outside any critical portions.<br></div><div><br></div=
><div>This makes me wonder how much we need to care about<br></div><div>=
trace_recovery_messages, actually, and I've never used it.<br></div></bl=
ockquote><div><br></div><div>IIUC trace_recovery_messages was a debuggin=
g aid in the 9.0 era when the HS was<br></div><div>introduced. I'm also =
wondering if anyone used it in the past years.<br></div><div><br></div><=
div>elog.c:<br></div><div><br></div><div>* Intention is to keep this for=
 at least the whole of the 9.0 production<br></div><div>* release, so we=
 can more easily diagnose production problems in the field.<br></div><di=
v>* It should go away eventually, though, because it's an ugly and<br></=
div><div>* hard-to-explain kluge.<br></div><div>*/<br></div><div>int<br>=
</div><div>trace_recovery(int trace_level)<br></div><div>{<br></div><div=
>&nbsp;&nbsp;&nbsp; if (trace_level &lt; LOG &amp;&amp;<br></div><div>&n=
bsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; trace_level &gt;=3D trace_recov=
ery_messages)<br></div><div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; r=
eturn LOG;&nbsp;<br></div><div><br></div><div>&nbsp;&nbsp;&nbsp; return =
trace_level;<br></div><div>}<br></div><div><br></div><div><br></div><div=
 id=3D"sig112409080"><div class=3D"signature">--<br></div><div class=3D"=
signature">Euler Taveira<br></div><div class=3D"signature">EDB&nbsp;&nbs=
p; <a href=3D"https://www.enterprisedb.com/">https://www.enterprisedb.co=
m/</a><br></div></div><div><br></div></body></html>
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