Re: max # of columns in the table (again!)

Hi,

Well, to conclude, dont' use tables with a large number of columns because of performance issues and bugs.

How Oracle chain rows depend on the average row length: - If a the rows are small, Oracle will store several rows in a block, there will be logical chaining, no problem ! - If the rows are larges and if one row don't fit in a block, there will be chaining accross blocks, logical ! - If rows are small enough to fit in a block, but the size are almost the size of the block, Oracle will store juste one row in a block !!!! Oracle will always store all the pieces (a piece = 255 columns) of a row in the same block.

About bugs, the first one (and it's not the last), you can't use dbms_stats against a partitionned table with more than ~ 200 columns. Bug 2603036.

Dias

ydias_at_hotmail.com (dias) wrote in message news:<55a68b47.0302152244.37694f38_at_posting.google.com>...
> Thank you all,
>
> I agree, it's a design problem.
>
> But I'm serching for arguments to prove that this design is bad.
>
> I have to migrate data from an old application to Oracle, the database
> users, it's a DTWH, don't want to change the data model, and prefer to
> work with wide tables, rather than small ones whith joins.
>
> Thanks.
>
> ydias_at_hotmail.com (dias) wrote in message news:<55a68b47.0302142315.39934901_at_posting.google.com>...
> > Hi,
> >
> > 1000 columns is the max for a table (8i and 9i).
> >
> > Oracle (8i) has an internal limit of 255. That means that if any
> > columns beyond 255 are not null, that row will always be chained.
> >
> > Is this still the case in 9i ?
> >
> > Thanks
Received on Sun Mar 09 2003 - 01:11:02 CST