From: Tom Lane <tgl@sss.pgh.pa.us>
To: Arjun Ranade <ranade@nodalexchange.com>
cc: pgsql-admin@postgresql.org
Subject: Re: Missing Chunk Error when doing a VACUUM FULL operation - DB
 Corruption?
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Comments: In-reply-to Arjun Ranade <ranade@nodalexchange.com>
	message dated "Tue, 31 Oct 2017 17:27:41 -0400"
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Date: Tue, 31 Oct 2017 17:56:14 -0400
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Arjun Ranade <ranade@nodalexchange.com> writes:
> Yes, it is still reproducible.  When I try to VACUUM FULL right now, I get
> the same error.

> This is postgres 9.4.  I am new to gdb, but based on what you said, I have
> the following output:

> Breakpoint 1, 0x0000000000768be0 in errfinish ()
> (gdb) bt
> #0  0x0000000000768be0 in errfinish ()
> #1  0x000000000076998c in elog_finish ()
> #2  0x0000000000495960 in ?? ()
> #3  0x0000000000496075 in heap_tuple_fetch_attr ()
> #4  0x0000000000496572 in toast_insert_or_update ()
> #5  0x0000000000492ce1 in ?? ()
> #6  0x0000000000493733 in rewrite_heap_tuple ()
> #7  0x000000000053ebdf in ?? ()
> #8  0x000000000053f68e in cluster_rel ()
> #9  0x0000000000590a1b in ?? ()
> #10 0x0000000000590f9f in vacuum ()
> #11 0x000000000068ee77 in standard_ProcessUtility ()

Hm.  I suspect what is happening is that VACUUM is trying to copy a tuple
that you deleted, but which it thinks is still visible to some open
transaction.  Do you have any really old transactions hanging around,
according to pg_stat_activity or pg_prepared_xacts?

If that is not it, probably truncating pg_statistic instead of just
doing "delete from pg_statistic" would solve the problem.  But we're
no closer to understanding what was the original source of the issue.

			regards, tom lane


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