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Re: maximum digits for NUMERIC

From: Gianni Ciolli <gianni(dot)ciolli(at)2ndquadrant(dot)it>
To: Noah Misch <noah(at)leadboat(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: maximum digits for NUMERIC
Date: 2011-04-01 10:44:23
Message-ID: 20110401104423.GF6543@albo.gi.lan (view raw or flat)
Thread:
Lists: pgsql-hackers
On Fri, Apr 01, 2011 at 03:52:22AM -0400, Noah Misch wrote:

> NumericLong has a 14-bit count of decimal digits for the dscale, giving that
> fractional digit limit.  It stores the weight as a 16-bit signed count of
> base-10000 "digits" after the first.  For example, 10^4-1 has weight 0, 10^4
> through 10^8 - 1 have weight 1, 10^8 has weight 2, etc.  For purposes of hitting
> the positive limit, we have 15 bits of weight.  Therefore, it can represent up
> to 2^15 * 4 = 2^17 digits.

OK; thanks also for the explaination.

> 
> > --- a/doc/src/sgml/datatype.sgml
> > +++ b/doc/src/sgml/datatype.sgml
> 
> There's a table further up on this page that lists of the range of each type,
> with "no limit" listed for numeric.  It could use an update noting with the
> supported extremes and fractional digit limit.

OK. 

Please find attached v2 of the numeric-doc patch, which takes into
account your remarks. In particular, numeric limits are now correct
and documented only in that table.

Best regards,
Dr. Gianni Ciolli - 2ndQuadrant Italia
PostgreSQL Training, Services and Support
gianni(dot)ciolli(at)2ndquadrant(dot)it | www.2ndquadrant.it

Attachment: patch-numeric-doc-v2.diff
Description: text/x-diff (1.8 KB)

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