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getQuadrant() places a point on each axis with the fuzzy comparisons FPlt(), FPgt() and FPeq(), which do not cover every case. FPeq() compares the rounded difference against EPSILON, while FPlt() and FPgt() round the sum of one operand and EPSILON. When the centroid plus EPSILON rounds up, a point equal to that rounded sum is more than EPSILON above the centroid, so FPeq() is false. FPgt() compares it with the same rounded sum, so it is false too, and FPlt() is false because the point is above the centroid. The same gap exists below the centroid, when the centroid minus EPSILON rounds down. No quadrant matches, and index builds, inserts and searches fail with "getQuadrant: impossible case". To fix, fall back to deciding each axis separately: Use fuzzy tests first and then tiebreak with exact comparisons. That gives every finite value a quadrant (NaN coordinates are still an error). Points that matched a fuzzy test before are routed as before, so existing indexes remain valid. Bug: #19597 Reported-by: Michael Malis <malis@pgrust.com> Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com> Reviewed-by: Andrey Rachitskiy <pl0h0yp1@gmail.com> Reviewed-by: Pierre Forstmann <pierre.forstmann@gmail.com> Discussion: https://postgr.es/m/19597-39c532e61d78dff6@postgresql.org 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/.