Horton

Re: Improve search for missing parent downlinks in amcheck

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Alexander Korotkov <a.korotkov@postgrespro.ru>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-04-25T23:46:08Z
Lists: pgsql-hackers 
On Tue, Apr 16, 2019 at 12:00 PM Peter Geoghegan <pg@bowt.ie> wrote:
> On Mon, Apr 15, 2019 at 7:30 PM Alexander Korotkov
> <a.korotkov@postgrespro.ru> wrote:
> > Currently we amcheck supports lossy checking for missing parent
> > downlinks.  It collects bitmap of downlink hashes and use it to check
> > subsequent tree level.  We've experienced some large corrupted indexes
> > which pass this check due to its looseness.
>
> Can you be more specific? What was the cause of the corruption? I'm
> always very interested in hearing about cases that amcheck could have
> detected, but didn't.

Ping?

I am interested in doing better here. The background information seems
very interesting.

-- 
Peter Geoghegan

Commits

  1. Improve checking of child pages in contrib/amcheck.

  2. Don't rely on estimates for amcheck Bloom filters.