Thread

1. BUG #18835: spgist index fails to accept point with NaN

   The Post Office <noreply@postgresql.org> — 2025-03-07T18:00:01Z

   The following bug has been logged on the website:
   
   Bug reference:      18835
   Logged by:          Alexander Lakhin
   Email address:      exclusion@gmail.com
   PostgreSQL version: 17.4
   Operating system:   Ubuntu 24.04
   Description:        
   
   The following script:
   CREATE TABLE t(p point);
   INSERT INTO t SELECT point(g, g) FROM generate_series(1, 1000) g;
   INSERT INTO t VALUES ('(0,NaN)'::point);
   
   CREATE INDEX spgist_idx ON t USING spgist(p);
   triggers:
   ERROR:  XX000: getQuadrant: impossible case
   LOCATION:  getQuadrant, spgquadtreeproc.c:77
   
   Reproduced starting from 8daeb5ddd.
   
   This anomaly is discovered with SQLsmith.
   
   

2. Re: BUG #18835: spgist index fails to accept point with NaN

   Tom Lane <tgl@sss.pgh.pa.us> — 2025-03-07T20:08:20Z

   PG Bug reporting form <noreply@postgresql.org> writes:
   > The following script:
   > CREATE TABLE t(p point);
   > INSERT INTO t SELECT point(g, g) FROM generate_series(1, 1000) g;
   > INSERT INTO t VALUES ('(0,NaN)'::point);
   
   > CREATE INDEX spgist_idx ON t USING spgist(p);
   > triggers:
   > ERROR:  XX000: getQuadrant: impossible case
   
   Yeah.  There's been some past attempts to clean up our behavior
   for NaNs in geometric values, but it's such a mess that not
   much progress has been made.  So I can't get excited about
   worrying about this case in particular (especially since I don't
   see any easy fix).  I wonder if we shouldn't just ban NaNs in
   the geometric types.
   
   			regards, tom lane