Re: dba - minextents/maxextents

In article <80hl1v$2l9$1_at_nnrp1.deja.com>,   Nandakumar <N.Kumar_at_rocketmail.com> wrote:
> the terms used below pertain to the storage parameters in
> CREATE TABLESPACE statement.
>
> could you also explain where and how MINEXTENTS is used?
> i am still not clear with its concept? If MINEXTENTS is used to
specify
> the minimum extents to be allocated on creation of a segment (say
table
> etc), what is the use of INITIAL? Does MINEXTENTS override INITIAL?
>
> btw, in my prev. posts PCTINCREASE was ZERO.
>

INITIAL determines the amount of storage is taken up by the first extent. MINEXTENTS determines the number of extents which will be created.

e.g. (INITIAL 1M NEXT 1M MINEXTENTS 2) would reserve 2M of storage in two extents.
(INITIAL 2M NEXT 1M MINEXTENTS 1) would reserve 2M of storage in one extent.

If you had a tablespace which was badly fragmented and you wanted to create table and allocate it, say, 10M, but the biggest piece of contigious free space was say 6M and the next biggest piece of free space was, say, 5M, then you could go (INITIAL 5M NEXT 5M MINEXTENTS 2) and this would reserve 10M in total for the table.

Of course, since you would be following my recommendations, you would never end up with a badly fragmented tablespace and hence you would never need to do this :).

So basically, most of the time, you can ignore MINEXTENTS and allow it to default.

The other situation is Rollback Segments where you can use something like
(INITIAL 1M NEXT 1M MINEXTENTS 8 OPTIMAL 8M) N.B. The minimum number of extents for a Rollback Segment is 2.

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Before you buy. Received on Fri Nov 12 1999 - 21:32:33 CST