From: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
---|---|
To: | Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> |
Cc: | Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: BRIN minmax multi - incorrect distance for infinite timestamp/date |
Date: | 2023-10-17 20:25:38 |
Message-ID: | 31400145-6f71-a6b2-e371-048a8e1584ef@enterprisedb.com |
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Thread: | |
Lists: | pgsql-hackers |
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
Attachment | Content-Type | Size |
---|---|---|
0001-Tests-for-overflows-with-dates-and-timestamps-in-BRI.patch | text/x-patch | 9.2 KB |
0002-Fix-overflow-in-brin_minmax_multi_distance_timestamp.patch | text/x-patch | 1011 bytes |
0003-Fix-calculation-in-brin_minmax_multi_distance_date.patch | text/x-patch | 1.2 KB |
0004-Add-tests-for-inifite-date-timestamp-values.patch | text/x-patch | 8.0 KB |
0005-Fix-handling-of-infinity-date-timestamp-values.patch | text/x-patch | 1.6 KB |
0006-Add-test-for-BRIN-minmax-multi-with-extreme-interval.patch | text/x-patch | 3.2 KB |
0007-Fix-distance-calculation-for-extreme-interval-values.patch | text/x-patch | 2.6 KB |
0008-Add-more-tests-for-BRIN-on-interval-values.patch | text/x-patch | 4.5 KB |
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