Re: Extents & MAXEXTENTS

Md Irfan wrote:

> Hi,
> I would like to know the default Maxextents storage clause of Create
> Table. I have for example two tables:
>
> TABLE_NAME INITIAL_EX NEXT_EXTEN MIN_EXTENT MAX_EXTENT PCT_INCREA
> -----------------------------------------------------------------------
> T1 262215680 125849600 1 121 50
> T2 178319360 83894272 1 121 50
>
> Can anyone help me in understanding if initial_extent is not defined
> while creating table, how does the value of initial_extent for T1, T2
> come from?
> When I query, dba_extents I get extent_id is 0 (zero) for all the
> tables. I have noticed that initial_extent keeps on growing but no
> changes in extent_id (always zero). Is that the data written in the
> first extent only.
> Also what in case if table needs extents more than max_extents.
> Thanks...
>

Quite some tables you got there.
If you create a table without a storage clause, the initial and next extend will be taken from the tablespace. Unless it is a locally managed one, of course. You can only define the initial extent then - leave it off, and the tablespace defaults will be used.

Your pct_increase is 50 - most DBA's don't like that because of the calculations involved: 1k, 1.5k, 2.25k, ? This in turn causes overhead in the form of extent management, which is not helping performance.

Last question: how did you query the initial extent? It cannot be growing (AFAIK), it can only get filled up - meaning it has been created even larger than 250MB.
Unless your "growth" is the result of export/import (and leaving compress to the default of "Y") Received on Tue May 07 2002 - 16:43:11 CDT