Re: numeric/decimal docs bug? - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: numeric/decimal docs bug?
Date
Msg-id 200204130139.g3D1d9k13453@candle.pha.pa.us
Whole thread Raw
In response to Re: numeric/decimal docs bug?  (Jan Wieck <janwieck@yahoo.com>)
List pgsql-hackers
Jan Wieck wrote:
> > Oh, interesting, maybe we should just leave it alone.
> 
>     As  said, I have to look at the code. I'm pretty sure that it
>     currently will not use hundreds of digits internally  if  you
>     use  only  a  few digits in your schema. So changing it isn't
>     that dangerous.
> 
>     But who's going to write and run a regression test,  ensuring
>     that  the  new  high  limit can really be supported. I didn't
>     even run the numeric_big test lately, which  tests  with  500
>     digits  precision  at least ... and therefore takes some time
>     (yawn). Increasing the number of digits used you  first  have
>     to  have  some  other  tool  to  generate  the  test  data (I
>     originally used bc(1) with some scripts). Based  on  that  we
>     still  claim that our system deals correctly with up to 1,000
>     digits precision.
> 
>     I don't like the idea of  bumping  up  that  number  to  some
>     higher  nonsense, claiming we support 32K digits precision on
>     exact numeric, and noone ever tested if  natural  log  really
>     returns  it's  result  in  that precision instead of a 30,000
>     digit precise approximation.
> 
>     I missed some of the discussion,  because  I  considered  the
>     1,000 digits already beeing complete nonsense and dropped the
>     thread. So could someone please enlighten me  what  the  real
>     reason  for  increasing  our  precision  is?   AFAIR  it  had
>     something to do with the docs. If it's just because the  docs
>     and  the code aren't in sync, I'd vote for changing the docs.

Jan, if the numeric code works on 100 or 500 digits, could it break with
10,000 digits.  Is there a reason to believe longer digits could cause
problems not present in shorter tests?

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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