Re: Sizing Oracle73 Indexes

Hi,

a formula taken from Corey/Abbey/Dechichio's 'Tuning Oracle':

greatest( 4, (1.01) * ((ROW_COUNT/

	((floor(((DB_BLOCK_SIZE - 113- (INITRANS * 23)) * (1 - PCTFREE/100.)))/
	(( 10 + UNIQUENESS) + NUMBER_COL_INDEX + (TOTAL_COL_LENGTH))))))*2))

Hope the're no typos.

ROW_COUNT:		extimated number of rows held in table
DB_BLOCK_SIZE:		parameter in the INIT<SID>.ORA-file
INITRANS:		parameter during index creation or default value
PCTFREE:		percent free specified during index creation
UNIQUENESS:		set to 1 if index is unique, else 0
NUMBER_COL_INDEX:	Number of coulumns in the index
TOTAL_COL_LENGTH:	sums the estimated average length of the index columns

rjuliatto_at_my-dejanews.com schrieb:
>
> Hello
>
> I have been using the hints at Oracle DBA Handbook in order to size the
> indexes my database will use. However, usually the size needed is larger
> than that calculated.
>
> I believe this must be due to fragmentation of indexes and/or overhead. Is
> there a more complete and explainable formula (I have seen some heuristic
> and unexplainable ones) to calculate the size of the indexes, foreseeing
> overhead and fragmentation?
>
> Thanks in advance
>
> Ronaldo Juliatto
>
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--

Regards

Matthias Gresz :-)

--
Matthias.Gresz_at_Privat.Post.DE

Galopping Horse beats Running Man. Received on Wed Sep 30 1998 - 03:17:21 CDT