| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Brian Hurt <bhurt(at)janestcapital(dot)com> |
| Cc: | pgsql-novice(at)postgresql(dot)org |
| Subject: | Re: probable faq: internal format of numerics |
| Date: | 2006-04-25 18:09:53 |
| Message-ID: | 22801.1145988593@sss.pgh.pa.us |
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| Lists: | pgsql-novice |
Brian Hurt <bhurt(at)janestcapital(dot)com> writes:
> That said, it looks like they're doing a variant of my #2- they're
> holding 5 decimal digits every 2 bytes, plus an extra byte or so for the
> sign.
Four digits per 2 bytes, actually ... five wouldn't fit (99999 > 65535).
> But consider the NumericVar structure defined in numeric.c- is
> one of those stored with every row of a table,
NumericVar is just a transient calculational representation.
NumericData (in numeric.h) is what's stored in the database. So it's
basically 8 bytes overhead plus 2 bytes for each group of 4 decimal
digits.
regards, tom lane
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