Re: Problem: database table/index sizing for Sum Length Columns greater than Available Data Space

Brendan Newman <bis_at_ibm.net> wrote in message news:379c4cd5_at_news1.us.ibm.net...
> Hi there,
>
> I am trying to size Oracle 8.x tables and am having difficulty due to
> the fact that the formulas Oracle gives are only appropriate if your Space
> Used Per Row (i.e. Sum Length Columns + Overhead) is less than your
> Available Data Space (i.e. Block_Size - Header Space - Pct_Free_Space).

The max total size of indexed columns is "40%*db_block_size - some overhead". In some version, the manual says "half of db_block_size - some overhead".

> What if Space Used Per Row >= Available Data Space? That is, what if
> you have big columns which are much bigger than your block size and you
> don't want to increase the block size?

You will get an error message 'ORA-01450: maximum key length n exceeded' when creating the index.
In general, such an index is impractical and poor-designed. You should re-examine your database design.

> If you could point me to where there are formulas for this particular
> case please let me know. Thanks. My e-mail is bis_at_ibm.net.
Received on Tue Jul 27 1999 - 10:14:17 CDT