From: Tom Lane <tgl@sss.pgh.pa.us>
To: Scott Ribe <scott_ribe@elevated-dev.com>
cc: Wasim Devale <wasimd60@gmail.com>,
        pgsql-admin <pgsql-admin@postgresql.org>
Subject: Re: Dead lock after the migration from CentOS 7 to RHEL 9
In-reply-to: <07994165-F268-41E0-9975-4FB5DE2EBED1@elevated-dev.com>
References: 
 <CAB5fag444HCM8xONrKbg+rJ5odCdy=0vmianN2Si5K5mWRFKvQ@mail.gmail.com>
 <CAB5fag6QPm1OE7H6roywzovDxb9rT9Wx-MdeiuK=mDvx6NTwtw@mail.gmail.com>
 <CAKFQuwbHt_56dOP-Fjtaj2C9KVJN14-L9LrDUf5AeWyW21g7KQ@mail.gmail.com>
 <CAB5fag7hsyWJUv=KezM=10RZ8hs=3fDkR4vMmJvn-Fjv3O0oeA@mail.gmail.com>
 <CAKFQuwYyFBgKKtJwFAOOsd2NahG6g8ymFKy_KpqhcoHdb_Nd3g@mail.gmail.com>
 <CAB5fag47NNn4T1e-t7YkLkqQbdammAvgDeb423ThaY=VjkSTOQ@mail.gmail.com>
 <07994165-F268-41E0-9975-4FB5DE2EBED1@elevated-dev.com>
Comments: In-reply-to Scott Ribe <scott_ribe@elevated-dev.com>
	message dated "Wed, 14 Aug 2024 21:45:29 -0600"
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Scott Ribe <scott_ribe@elevated-dev.com> writes:
> Given errors like the pair you posted, my next step would be to examine =
the queries being executed by those processes during the deadlock. Now, I =
think by the time the deadlock error is logged, the queries involved have =
been cancelled, so it's possible the processes have gone on to another que=
ry and so pg_stat_activity might not have useful information, or it might-=
-depending on what your app would do after a deadlock error.
> If it does not, then the next thing would be to set log_min_duration_sta=
tement to less than deadlock/statement timeout, so that you could look thr=
ough logs to figure out what are the two queries which are deadlocking aga=
inst each other.

The postmaster log should already contain the statements that
deadlocked against each other --- that's what the "HINT: See server
log for query details" is telling you.

			regards, tom lane