| From: | Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com> |
|---|---|
| To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Bruce Momjian <bruce(at)momjian(dot)us>, Floris Van Nee <florisvannee(at)optiver(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: visibility map corruption |
| Date: | 2021-07-06 22:12:31 |
| Message-ID: | E2724621-256F-4215-B1EA-B10E8B4867F9@enterprisedb.com |
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| Lists: | pgsql-hackers |
> On Jul 6, 2021, at 2:27 PM, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
>
> It looks like amcheck's verify_heapam.c functionality almost catches
> bugs like this one. Something for Mark (CC'd) to consider. Does it
> matter that we usually "ctx.oldest_xid = ctx.relfrozenxid", and so
> usually use pg_class.relfrozenxid as our oldest_xid (and not
> ShmemVariableCache->oldestXid)? In other words, could we be doing more
> to sanitize ShmemVariableCache->oldestXid, especially when the
> relation's pg_class.relfrozenxid happens to be set to a real XID?
Thanks, Peter, for drawing my attention to this. I had already been following this thread, but had not yet thought about the problem in terms of amcheck.
I will investigate possible solutions in verify_heapam().
—
Mark Dilger
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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