From: | "Luke Lonergan" <llonergan(at)greenplum(dot)com> |
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To: | "Stephen Frost" <sfrost(at)snowman(dot)net> |
Cc: | "D'Arcy J(dot)M(dot) Cain" <darcy(at)druid(dot)net>, pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: New version of money type |
Date: | 2006-09-28 17:02:04 |
Message-ID: | C1414E1C.2E0C%llonergan@greenplum.com |
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Stephen,
On 9/28/06 9:44 AM, "Stephen Frost" <sfrost(at)snowman(dot)net> wrote:
> I'm not sure about 'money' in general but these claims of great
> performance improvments over numeric just don't fly so easily with me.
> numeric isn't all *that* much slower than regular old integer in the
> tests that I've done.
Part of the problem is the *size* of Numeric. I've just looked for
something that describes the size of a Numeric and I saw an old post that
says:
10 + x/2 bytes
So, a minimum of 10 bytes (compared to the 8 proposed for money64) plus
scale (x) divided by two.
Currently on the TPC-H benchmark, Postgres requires 1.7 times the amount of
internal database storage as what is in the ASCII data file representation.
Oracle and MSFT SQLServer are almost 1:1. Part of this fluff is the 24
bytes of tuple header, part of it is in the Numeric.
- Luke
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