From: Tom Lane Date: Tue, 5 Aug 2025 20:51:10 +0000 (-0400) Subject: Fix incorrect return value in brin_minmax_multi_distance_numeric(). X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=80c758a2e1d720a942610f2f889448d69ce2ce95;p=thirdparty%2Fpostgresql.git Fix incorrect return value in brin_minmax_multi_distance_numeric(). The result of "DirectFunctionCall1(numeric_float8, d)" is already in Datum form, but the code was incorrectly applying PG_RETURN_FLOAT8() to it. On machines where float8 is pass-by-reference, this would result in complete garbage, since an unpredictable pointer value would be treated as an integer and then converted to float. It's not entirely clear how much of a problem would ensue on 64-bit hardware, but certainly interpreting a float8 bitpattern as uint64 and then converting that to float isn't the intended behavior. As luck would have it, even the complete-garbage case doesn't break BRIN indexes, since the results are only used to make choices about how to merge values into ranges: at worst, we'd make poor choices resulting in an inefficient index. Doubtless that explains the lack of field complaints. However, users with BRIN indexes that use the numeric_minmax_multi_ops opclass may wish to reindex in hopes of making their indexes more efficient. Author: Peter Eisentraut Co-authored-by: Tom Lane Discussion: https://postgr.es/m/2093712.1753983215@sss.pgh.pa.us Backpatch-through: 14 --- diff --git a/src/backend/access/brin/brin_minmax_multi.c b/src/backend/access/brin/brin_minmax_multi.c index b85a70a0db2..a5a414182ca 100644 --- a/src/backend/access/brin/brin_minmax_multi.c +++ b/src/backend/access/brin/brin_minmax_multi.c @@ -2032,7 +2032,7 @@ brin_minmax_multi_distance_numeric(PG_FUNCTION_ARGS) d = DirectFunctionCall2(numeric_sub, a2, a1); /* a2 - a1 */ - PG_RETURN_FLOAT8(DirectFunctionCall1(numeric_float8, d)); + PG_RETURN_DATUM(DirectFunctionCall1(numeric_float8, d)); } /*