doc: adjust PG 12 relnotes item on float digit adjustment

Discussion: https://postgr.es/m/87y330d8ty.fsf@news-spur.riddles.org.uk
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Bruce Momjian 2019-05-21 16:31:02 -04:00
parent 0fca8285ea
commit b84a801d6a

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@ -207,18 +207,16 @@ Author: Andrew Gierth <rhodiumtoad@postgresql.org>
-->
<para>
Avoid performing unnecessary rounding of <link
linkend="datatype-float"><type>REAL</type></link> and <type>DOUBLE
PRECISION</type> values (Andrew Gierth)
Improve performance by changing the default number of trailing digits
output for <link linkend="datatype-float"><type>REAL</type></link>
and <type>DOUBLE PRECISION</type> values (Andrew Gierth)
</para>
<para>
This dramatically speeds up processing of floating-point
values but causes additional trailing digits to
potentially be displayed. Users wishing to have output
that is rounded to match the previous behavior can set <link
linkend="guc-extra-float-digits"><literal>extra_float_digits=0</literal></link>,
which is no longer the default.
Previously, float values were output rounded to 6 or 15 decimals
by default. Now, only the number of digits required to preserve
the exact binary value is output. The previous behavior can be
restored by setting <xref linkend="guc-extra-float-digits"/> to zero.
</para>
</listitem>