[ To: header pruned ] >>>>> "Andres" == Andres Freund <and...@anarazel.de> writes:
Andres> <para> Andres> Avoid performing unnecessary rounding of <link Andres> linkend="datatype-float"><type>REAL</type></link> and <type>DOUBLE Andres> PRECISION</type> values (Andrew Gierth) Andres> </para> Andres> <para> Andres> This dramatically speeds up processing of floating-point Andres> values but causes additional trailing digits to Andres> potentially be displayed. Users wishing to have output Andres> that is rounded to match the previous behavior can set <link Andres> linkend="guc-extra-float-digits"><literal>extra_float_digits=0</literal></link>, Andres> which is no longer the default. Andres> </para> Andres> </listitem> Andres> Isn't it exactly the *other* way round? *Previously* we'd Andres> output additional trailing digits. The new algorithm instead Andres> will instead have *exactly* the required number of digits? Yeah, this wording is not right. But your description is also wrong. Previously we output values rounded to 6+d or 15+d digits where d=extra_float_digits, with d=0 being the default. Only clients that wanted exact results would set that to 3 instead. Now we output the minimum digits to get an exact result, which is usually 8 or 17 digits (sometimes less depending on the value, or 9 for the relatively rare float4 values that need it) for any extra_float_digits value > 0. Clients that set d=3 will therefore usually get one less digit than before, and the value they get will usually be slightly different (i.e. not the same value that they would have seen with d=2), but it should give them the same binary value after going through strtod() or strtof(). -- Andrew (irc:RhodiumToad)
