| From: | Decibel! <decibel(at)decibel(dot)org> |
|---|---|
| To: | "Gangadharan S(dot)A(dot)" <gangadharan(at)gmail(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Storage space usage |
| Date: | 2008-02-02 06:37:09 |
| Message-ID: | 20080202063709.GR1212@decibel.org |
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| Lists: | pgsql-performance |
On Fri, Feb 01, 2008 at 02:14:18PM +0530, Gangadharan S.A. wrote:
> Hi,
> I have 2 questions regarding the storage optimization done by Postgres:
> 1) Is a NULL value optimized for storage. If I have a timestamp (or some
> such) field that I set to default NULL, will it still use up the full space
> for the data type.
Null values are indicated via a NULL bitmap. A null field is not stored,
it is just indicated in the bitmap.
> 2) Similarly, if I have a text array, is an empty array optimized for
> storage?
Arrays are stored as varlenas. I'm pretty sure than an empty array is
considered to be NULL; as such the comments above would apply.
--
Decibel!, aka Jim C. Nasby, Database Architect decibel(at)decibel(dot)org
Give your computer some brain candy! www.distributed.net Team #1828
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