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The float4 and float8 btree_gist opclasses compared keys with raw C operators (==, <, >). IEEE 754 makes every comparison involving NaN false, so GiST disagreed with the regular float comparison operators and with the btree opclass, which uses float[4|8]_cmp_internal() (so that all NaNs are equal and NaN sorts after every non-NaN value). In addition, the penalty and distance functions were not careful about NaNs, and the penalty functions could also misbehave for IEEE infinities. Wrong answers from the penalty functions would probably do no more than make the index non-optimal, but the distance mistakes were visible from SQL. To fix, make the comparison functions rely on the same NaN-aware comparison functions the core code uses, and rewrite the penalty and distance functions to follow the rules that NaNs are equal but maximally far away from non-NaNs. The penalty_num() code was formerly shared between integral and float cases, but I chose to make two copies so that the integral cases are not saddled with the extra logic for NaNs and infinities/overflows. I also rewrote it as static inline functions instead of an unreadable and uncommented macro. The float penalty functions were previously unreached by the regression tests, so add new test cases to exercise them. There's no on-disk format change, but users who have NaN entries in a btree_gist index would be well advised to reindex it. Bug: #19501 Bug: #19524 Reported-by: Man Zeng <zengman@halodbtech.com> Reported-by: Yuelin Wang <3020001251@tju.edu.cn> Author: Bill Kim <billkimjh@gmail.com> Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/19501-3bff3bbc97f1e7c9@postgresql.org Discussion: https://postgr.es/m/19524-9559d302c8455664@postgresql.org Discussion: https://postgr.es/m/CAMQXxcgbtD2LXfX0tpgvOizxP-XxrCHV2ZDy4By_TZnJMsxXWQ@mail.gmail.com Backpatch-through: 14
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.