Float output formatting options

Hi All,

This relates to the recent discussion about floating point output format.

The discussion was at a point where one parameter would be added to
specify the number of extra digits used in fp output formatting.
The parameter would have a 0 default value, a maximum of 2 and the
minimum remained open for discussion.

In a previous message I proposed that for double precision numbers a
minimum value of -13 would be usefful. For single precision numbers this
corresponds to a value of -4.

I downloaded the PG sources and added two parameters (as PGC_USERSET):

int extra_float4_digits, default 0, min -4, max 2
int extra_float8_digits, defualt 0, min -13, max 2

Compiled and tested for these functionalities. It is ok.

The afected files are:

src/backend/utils/adt/float.c
src/backend/utils/misc/guc.c
src/bin/psql/tab-complete.c
src/backend/utils/misc/postgresql.conf.sample

I used sources from Debian source package, postgresql_7.2.1-2woody2.

Diff's produced with diff -u are enclosed as attachments.
Can you comment on this (particularly the min values) ?
Also, if we concluded that there is a need of 2 more digits, should'nt
this be the default ?

Best regards,
Pedro M. Ferreira
--
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Pedro Miguel Frazao Fernandes Ferreira
Universidade do Algarve
Faculdade de Ciencias e Tecnologia
Campus de Gambelas
8000-117 Faro
Portugal
Tel./Fax: (+351) 289 800950 / 289 819403
http://w3.ualg.pt/~pfrazao