Date: Thu, 15 Nov 2018 17:28:04 -0300
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Ron <ronljohnsonjr@gmail.com>
Cc: Pgsql-admin <pgsql-admin@postgresql.org>
Subject: Re: Can't find a relation in pg_class
Message-ID: <20181115202804.kup5jpbkx6tf7zxe@alvherre.pgsql>
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On 2018-Nov-15, Ron wrote:

> On 11/15/2018 02:02 PM, Alvaro Herrera wrote:
> > On 2018-Nov-15, Ron wrote:
> > 
> > > On 11/15/2018 12:56 PM, Tom Lane wrote:
> > > > Ron <ronljohnsonjr@gmail.com> writes:
> > > > > 10.143.169.100(38184) TAP TAPb 14310 PARSE waiting [unknown] 00000
> > > > >           LOG:  process 14310 still waiting for AccessShareLock
> > > > >           on relation *767445914* of database *767442254* after 1000.389 ms at
> > > > > character 39
> > > > > We found this in the log file, so went looking for what relation 767445914
> > > > > is, but don't see it in the pg_class table.  Am I doing something wrong?
> > > > This message would be citing relation OID not relfilenode, I believe.
> > > In what table?
> > select ... from pg_class where oid = 767445914
> 
> That's what I thought.  But select oid, relfilenode from pg_class shows that
> c.oid always has the same value as c.relfilenode.

Then the other cases Tom mentioned apply.

(Note that that equality doesn't apply in general.  The relfilenode will
change on VACUUM FULL, or CLUSTER, or table-rewriting ALTER TABLE,
whereas the OID will always stay unchanged.)

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services