Re: general recommendations for setting block size?

On Thu, 9 Sep 1999 23:47:54 +1000, you wrote:

>Very good point, Thomas. Same reason as
>large cluster sizes waste disk. If you have a database
>with lots and lots of very small tables and a few large ones,
>it is quite possible that some of the 8K block size will be
>wasted for the small tables. A special case, agreed. But also
>one that strikes quite often, unfortunately. Particularly if the
>database is subjected to creation and drop of small temporary
>tables as the application(s) executes.
>

if you have lots of tables with the minimum 2 or so blocks -- you'll at most waste 8k/table.

If you have 1,000 tables that are less then 8k in size, you'll have wasted 1,000*8k or 8,000k or 8meg of space. In database terms, 8meg is nothing.

8k takes less space then 4k in a database.

The large cluster problem you have with 10's of thousands of files of very small (couple of bytes) size on an OS filesystem just isn't really relevant in a database with database tables. The smallest of tables is large relative to small .dat files in an OS. The analogy doesn't hold up.

>Then again as I said, with technology going the way it is going
>I wouldn't be surprised if this didn't change soon.
>Currently the only thing I can see that might be really counter-productive
>with the 8K size is the speed of transfer in multiple access: 8K * lots
>of I/O transfer makes for expen$ieve overall I/O bandwidth. This will
>change soon.

--
See http://govt.us.oracle.com/~tkyte/ for my columns 'Digging-in to Oracle8i'... Current article is "Part I of V, Autonomous Transactions" updated June 21'st  

Thomas Kyte                   tkyte_at_us.oracle.com
Oracle Service Industries     Reston, VA   USA

Opinions are mine and do not necessarily reflect those of Oracle Corporation Received on Thu Sep 09 1999 - 09:15:45 CDT