Re: big batch & small transactions at same time?

>>>>> "Jay" == Jay M Scheiner <jxs_at_wolpoff_nospm_law.com> writes:

 Jay> How practical is it to have a system running that would
 Jay> have hundreds of users doing OLTP (lots of small
 Jay> transactions) while at the same time (occasionally) doing
 Jay> big batch work with larger transactions?  I am thinking of
 Jay> rollback segments here.

I have read in a couple of places, and have used this rule of thumb in design on my last project, that you estimate how many concurrent users at one time, then you define 1/4th of that number for your rollback segments.

The size of the RBS needs to be as big as your largest transaction.

What this accomplishes, is that you alleviate alot of contention for the same transactions vieing for the same rollback segments

 Jay> Does it hurt the OLTP work much to have larger rollback
 Jay> segments?  My understanding is that you could have 1 big
 Jay> rollback segment for batch work, but you can't have it JUST
 Jay> for those transactions.  That is, if an RBS is online,
 Jay> anyone can use it.

In any transaction, you can specify which RBS to use.

I also believe that you can partition out users and RBS, but I would have to dig through the documentation on that one. I believe that the large one doesn't have to be made available to the online transactions.

-- 
Galen Boyer
Database Architect
Primix Solutions, www.primix.com