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80c758a2e1
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 <peter@eisentraut.org> Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/2093712.1753983215@sss.pgh.pa.us Backpatch-through: 14