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 <pe...@eisentraut.org> Co-authored-by: Tom Lane <t...@sss.pgh.pa.us> Discussion: https://postgr.es/m/2093712.1753983...@sss.pgh.pa.us Backpatch-through: 14 Branch ------ REL_18_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/9b681e239726d254b18cf88ad94174e086bf1950 Modified Files -------------- src/backend/access/brin/brin_minmax_multi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
