Horton

Re: [BUG] Error in BRIN summarization

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2020-08-12T18:02:18Z
Lists: pgsql-hackers 
On 2020-Aug-11, Alvaro Herrera wrote:

> A much more troubling thought is what happens if the range is
> desummarized, then the index item is used for the summary of a different
> range.  Then the index might end up returning corrupt results.

Actually, this is not a concern because the brin tuple's bt_blkno is
rechecked before returning it, and if it doesn't match what we're
searching, the loop is restarted.  It becomes an infinite loop problem
if the revmap is pointing to a tuple that's labelled with a different
range's blkno.  So I think my patch as posted is a sufficient fix for
this problem.

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

Commits

  1. Disable autovacuum for BRIN test table

  2. Handle new HOT chains in index-build table scans

  3. BRIN: Handle concurrent desummarization properly