Horton

Re: BRIN minmax multi - incorrect distance for infinite timestamp/date

Tomas Vondra <tomas.vondra@enterprisedb.com>

View thread View on postgr.es
From: Tomas Vondra <tomas.vondra@enterprisedb.com>
To: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-10-17T20:25:38Z
Lists: pgsql-hackers

Attachments

Hi,

Here's a couple cleaned-up patches fixing the various discussed here.
I've tried to always add a regression test demonstrating the issue
first, and then fix it in the next patch.

In particular, this deals with these issues:

1) overflows in distance calculation for large timestamp values (0002)

2) incorrect subtraction in distance for date values (0003)

3) incorrect distance for infinite date/timestamp values (0005)

4) failing distance for extreme interval values (0007)

All the problems except "2" have been discussed earlier, but this seems
a bit more serious than the other issues, as it's easier to hit. It
subtracts the values in the opposite order (smaller - larger), so the
distances are negated. Which means we actually merge the values from the
most distant ones, and thus are "guaranteed" to build very a very
inefficient summary. People with multi-minmax indexes on "date" columns
probably will need to reindex.


regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Fix minmax-multi distance for extreme interval values

  2. Fix minmax-multi on infinite date/timestamp values

  3. Fix calculation in brin_minmax_multi_distance_date

  4. Fix overflow when calculating timestamp distance in BRIN