Re: Algorithm for calculating extent size in LMT

There is a degree to which initial, next, minextents are used even with LMTs. Oracle will calculate the nominal space requested according to these values, and then supply you with a number of extents according to its own policy that at least match that size.
E.g. in an LMT with uniform 2M, if you set

    initial = 3M, next = 10 M, minextents = 5, then Oracle will calculate

    3 + 4 * 10 = 43
and supply you with a starting size of 22 extents (i.e. the smallest number of extents that gives you at least 43MB).

It's harder to predict in an autoallocate, since it depends on what empty space actually exists already, but there is a fair chance that your starting segment would have

    3 x 1MB and 5 x 8MB.

--
Jonathan Lewis
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Ganesh Raja wrote in message ...


>Comments Embedded

>

>Regards,

>Ganesh R

>

>"EP" <ep_at_plusnet.pl> wrote in message news:<a60ff8$isp$1_at_news.tpi.pl>...

>> > There is no such thing. Extent sizes are determined by developers and

DBAs


>> > that do their homework and determine the idea size for a class of

tables.


>> > Often ... creating multiple tablespaces with different extent sizes to

>>  avoid

>> > both fragmentation and keep the number of segments ?small.

>>

>> You are mistaken here, as with the autoallocate option you also have to

>> calculate such parameters as INITIAL, NEXT and  MINEXTENTS, so DBA

homework


>> is done as well !!!

>

>Are You Sure...  I Feel you are talking about Dict Managed TBS and

>that is almost History now considering 9i is pushing for LMT's in a

>Big way.

>

>LMTS Dont use the Initial Next and MinExtents they are ignored when a

>TBS is declared as a LMT.

>

>> As  far as the number of extens goes, Oracle's calculation is based on

the


>> above parameters, so you don't need to worry about too many extents

(unless


>> you have made a mistake while estimating these parameters).

>

>Absolutley Wrong ... See above !!!

>

>>

>> Regards,

>> EP