Re: Discrepancy in query output - Mailing list pgsql-sql

From Lahari Sengupta
Subject Re: Discrepancy in query output
Date
Msg-id CAKEx41r1QzgUYNnOinsM9-ge_mx+Bux_GBBM8tNdGSvzunMHTQ@mail.gmail.com
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In response to Re: Discrepancy in query output  ("David G. Johnston" <david.g.johnston@gmail.com>)
List pgsql-sql
Ok. I tried to find out the extra row. And single with it returns true.

On Thu, Feb 22, 2018 at 5:54 PM, David G. Johnston <david.g.johnston@gmail.com> wrote:
On Thu, Feb 22, 2018 at 6:56 AM, Lahari Sengupta <jhinik8@gmail.com> wrote:
Specially, if I remove the timing condition and want to select all from servers then it misses one. How is it possible?
 
st_distance(sv.geom, st.geom)<8.5) where


​Apparently st_distance() is non-deterministic in its output of float representations.  Its seems likely (though I'm by no means fluent on floating-point concerns) to be a problem specific to the implementation of that function and thus better asked on a PostGIS list.  You should identify the "extra" row and see if you can include it in a self-contained query that demonstrates occasionally returning false for the condition when normally it returns true.

David J.


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