Re: BUG #14932: SELECT DISTINCT val FROM table gets stuck in aninfinite loop - Mailing list pgsql-bugs

From Andres Freund
Subject Re: BUG #14932: SELECT DISTINCT val FROM table gets stuck in aninfinite loop
Date
Msg-id 20180126234741.4wswfztzkuqrotnv@alap3.anarazel.de
Whole thread Raw
In response to Re: BUG #14932: SELECT DISTINCT val FROM table gets stuck in an infinite loop  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-bugs
On 2018-01-26 18:22:26 -0500, Tom Lane wrote:
> In any case, we still need a fix for the behavior that the hash table size
> is blown out by lots of collisions, because that can happen no matter what
> the hash function is.  Andres seems to have dropped the ball on doing
> something about that.

Didn't have spare brain cycles :(, and the next backbranch release
wasn't yet close reducing immediate urgency a bit.  As written nearby I
think we should make execGrouping.c users of hashtables use a more
random IV, and apply something similar to the growth limit patch from
Tomas.

Greetings,

Andres Freund


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