Re: postgresql storage and performance questions

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От Alvaro Herrera
Тема Re: postgresql storage and performance questions
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Msg-id 20071120124954.GE5167@alvh.no-ip.org
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Ответ на Re: postgresql storage and performance questions  ("Josh Harrison" <joshques@gmail.com>)
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Josh Harrison escribió:

> > On 11/19/07, Josh Harrison <joshques@gmail.com> wrote:
> >
> > > I have 2 tables with 2 cols each( 1 numeric(8,0) and 1 varchar(3) ).
> > > In table1 both the cols are filled and in table2  the varchar colm is null

> There were a couple of things we noted.
> 1. Tablesize twice as much than oracle-- Im not sure if postgres null
> columns has any overhead since  we have lots of null columns in our
> tables.Does postgresql has lots of overhead for null columns?

No, NULLs are stored as a bitmap for each tuple and they are quite
efficient.

Probably the reason for the difference is the numeric field which Oracle
may be optimizing as a plain integer.   Did you try declaring the column
as INTEGER in Postgres?


Please do not top-post.

--
Alvaro Herrera                  http://www.amazon.com/gp/registry/5ZYLFMCVHXC
"Everything that I think about is more fascinating than the crap in your head."
                               (Dogbert's interpretation of blogger philosophy)

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