From: Tom Lane <tgl@sss.pgh.pa.us>
To: "James (Ke) Wang" <james.wang@sas.com>
cc: "pgsql-odbc@postgresql.org" <pgsql-odbc@postgresql.org>
Subject: Re: Bug? The precision from the ODBC API is not same to psql
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Comments: In-reply-to "James (Ke) Wang" <james.wang@sas.com>
	message dated "Mon, 30 Aug 2021 04:19:29 -0000"
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Date: Mon, 30 Aug 2021 10:02:25 -0400
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"James (Ke) Wang" <james.wang@sas.com> writes:
>   *   PostgreSQL ODBC driver version: 13.01.00
>   *   PostgreSQL database version: PostgreSQL 10.17 on x86_64-pc-linux-g=
nu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44), 64-bit
>   *   any error messages you saw on the screen: No. However the result f=
rom ODBC API is not expected, we expect the ODBC driver returns the result=
 same to Psql utility. Please see the below logs.

You can get the same result in psql, if you set extra_float_digits
correctly:

regression=3D# select 51.3::float8;
 float8 =

--------
   51.3
(1 row)
regression=3D# set extra_float_digits =3D 2;
SET
regression=3D# select 51.3::float8;
       float8       =

--------------------
 51.299999999999997
(1 row)

So presumably either ODBC or something in your application is
setting that parameter.

FWIW, PG version 12 and newer won't do that; they use a newer
floating-point printing algorithm with less inclination to
produce silly-looking results.

			regards, tom lane