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Fix handling of NaN values in BRIN minmax multi

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When calculating distance between float4/float8 values, we need to be a
bit more careful about NaN values in order not to trigger assert. We
consider NaN values to be equal (distace 0.0) and in infinite distance
from all other values.

On builds without asserts, this issue is mostly harmless - the ranges
may be merged in less efficient order, but the index is still correct.

Per report from Andreas Seltenreich. Backpatch to 14, where this new
BRIN opclass was introduced.

Reported-by: Andreas Seltenreich
Discussion: https://postgr.es/m/87r1bw9ukm.fsf@credativ.de
This commit is contained in:
Tomas Vondra
2021-11-06 01:25:31 +01:00
parent f214960add
commit d91353f4b2
3 changed files with 24 additions and 0 deletions
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17
src/backend/access/brin/brin_minmax_multi.c
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@@ -73,6 +73,7 @@
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datum.h"
#include "utils/float.h"
#include "utils/inet.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
@@ -1872,6 +1873,14 @@ brin_minmax_multi_distance_float4(PG_FUNCTION_ARGS)
float a1 = PG_GETARG_FLOAT4(0);
float a2 = PG_GETARG_FLOAT4(1);
/* if both values are NaN, then we consider them the same */
if (isnan(a1) && isnan(a2))
PG_RETURN_FLOAT8(0.0);
/* if one value is NaN, use infinite distance */
if (isnan(a1) || isnan(a2))
PG_RETURN_FLOAT8(get_float8_infinity());
/*
* We know the values are range boundaries, but the range may be collapsed
* (i.e. single points), with equal values.
@@ -1890,6 +1899,14 @@ brin_minmax_multi_distance_float8(PG_FUNCTION_ARGS)
double a1 = PG_GETARG_FLOAT8(0);
double a2 = PG_GETARG_FLOAT8(1);
/* if both values are NaN, then we consider them the same */
if (isnan(a1) && isnan(a2))
PG_RETURN_FLOAT8(0.0);
/* if one value is NaN, use infinite distance */
if (isnan(a1) || isnan(a2))
PG_RETURN_FLOAT8(get_float8_infinity());
/*
* We know the values are range boundaries, but the range may be collapsed
* (i.e. single points), with equal values.