Re: Table with 7000 columns?

"utkanbir" <hopehope_123_at_yahoo.com> wrote in message news:f6c90ebe.0411292239.42efe1f2_at_posting.google.com...
> Hi ,
>
> This is related to datawarehouse , data mining . We are told that data
> mining tools such as spss or sas , need a large table which has lots
> of columns inside . Based on our project , out final table which will
> be used in data mining , has lots of computed values . The final
> number of columns of the table is 7800!(lots of calculated values)
> First of all , i dont see the reason of this requirement of the data
> mining tools. I will be appreciated if someone can clarify this: Why
> does a data mining tool need such a large table?
>
> The main issue is if i create table with 7800 columns inside ( in fact
> oracle only allows to create table with 1000 columns) , i believe it
> cant be queried.
> My basic calculation shows that the average row size of this table
> will be 160kb. , considering my db_block_size of 16kb. this means 10
> blocks for 1 row. (The table will have more than 10.000.000 rows) No
> matter how fast my disk subsystem is , i think the queries against
> this table will fail. So what can i do? May be I need a different
> type of storage technique for instance column based storage ( i heard
> that sysbase has this feature , dont know the details / purpose..)
> How can i solve such a problem? The database server really does not
> matter , it can be oracle,sqlserver , sybase,informix , etc... I will
> be appreciated if someone can help me abut the issue.
>
> Kind Regards,
> hope

Usually with data mining you have narrow tables NOT wide tables. I suspect someone doesn't know what the heck they are doing. Solution: don't do that. I can't imagine a data warehouse having even 500 columns never mind 7K. Jim Received on Tue Nov 30 2004 - 02:57:55 CST