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Fix netmask handling in inet_minmax_multi_ops

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When calculating distance in brin_minmax_multi_distance_inet(), the
netmask was applied incorrectly. This results in (seemingly) incorrect
ordering of values, triggering an assert.

For builds without asserts this is mostly harmless - we may merge other
ranges, possibly resulting in slightly less efficient index. But it's
still correct and the greedy algorithm doesn't guarantee optimality
anyway.

Backpatch to 14, where minmax-multi indexes were introduced.

Reported by Dmitry Dolgov, investigation and fix by me.

Reported-by: Dmitry Dolgov
Backpatch-through: 14
Discussion: https://postgr.es/m/17774-c6f3e36dd4471e67@postgresql.org
This commit is contained in:
Tomas Vondra
2023-03-20 09:51:50 +01:00
parent 8de4660a57
commit 0c7726c282
3 changed files with 15 additions and 2 deletions
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4
src/backend/access/brin/brin_minmax_multi.c
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@@ -2364,14 +2364,14 @@ brin_minmax_multi_distance_inet(PG_FUNCTION_ARGS)
unsigned char mask;
int nbits;
nbits = lena - (i * 8);
nbits = Max(0, lena - (i * 8));
if (nbits < 8)
{
mask = (0xFF << (8 - nbits));
addra[i] = (addra[i] & mask);
}
nbits = lenb - (i * 8);
nbits = Max(0, lenb - (i * 8));
if (nbits < 8)
{
mask = (0xFF << (8 - nbits));