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Re: Numeric 508 datatype

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-patches(at)postgresql(dot)org
Subject: Re: Numeric 508 datatype
Date: 2005-12-02 18:03:26
Message-ID: 200512021803.jB2I3QH23903@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-hackerspgsql-patches
Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > So we are really decreasing the specified precision from 1000 to 508,
> > and the computational precision from 4096 to 508.
> 
> The internal computational precision isn't any less, the limit is only
> on the result of a function (ie, partial results within one of the
> numeric.c routines could still exceed 10^508).  Not sure how much that
> distinction matters though.

Agreed.

> > Is there any plan to
> > fix the silent overflow problem?  Is that in the patch?  I don't see it.
> 
> It will get fixed before application ;-)
> 
> I haven't reviewed the patch yet; I think the gating factor at this
> point is whether anyone protests losing dynamic range in NUMERIC,
> and we ought to go ahead and ask that.  After that we can look at the
> code more closely.

I am confused by your use of the term "dynamic" range.  From what you
say above that we are just moving from 1000 to 508 for storage, and that
computational range would still be 4096?

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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