Estimating a Data Mart's size?

From: david_spiers <david_spiers_at_sig.eds.com>
Date: 4 Sep 1998 09:10:31 GMT
Message-ID: <01bdd7e4$c6eedc60$fc810ea6@cxp335.citymax.co.uk>

I have been tasked with estimating the size of tables required by our datamart with a view to hardware requirements. To do this I have been trying to use the formula in Appendix A of the Oracle Server -release 8.0 Administrators guide. This requires me to find the sum of the column sizes for each table. This may take some time. I know that the average row length can be found by:

select table_name, avg_row_len from user_tables where table_name = 'TABLE_NAME'; but when I compare this value with the vsize() values the numbers I get are completely different (some a lot bigger, a lot some smaller). The statistics on these tables were recently analysed.

Can anyone tell me why there is such a difference?

Or better yet, a fast and accurate method of guestimating the size of a datamart given the number of rows, etc.

Cheers,

Robert Harfield
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The views etc. presented here reflect those of the individual and must in no way be attributed to the company Received on Fri Sep 04 1998 - 04:10:31 CDT