Merging Two DB into one DB

R

RP_wpb

New Member
Hi:
we have 2 database
Db1 - 300+ GB (around 400 tables)
DB2 - 500+ GB (around 350 tables)
progress 9.1E (will upgrade to OE in couple of months)
Database on solaris
maximum users (at peak time) : around 800
My query is - if we were to combine both database into one DB, will it affect DB performance (especially w.r.t BIW/AIW/APW process).currently we have 11 APW per DB.
The immediate thought I am getting is, that it might affect DB performance as one process will have more job to do if we combine the 2 DB.
Just wanted to get your opinion also.
thanks,
Raghu
 
It might.

It depends on the workload and what else you do. Especially if you change (or don't change) various startup parameters and configuration options.
 
We did something sorta similar - took multiple large db's (in our case more than 5) and merged into 1. We did it because managing so many databases was more of a problem than managing 1 very large database. You will lose performance merging your databases together when heavy processing occurs. Normal activity during the day shouldn't be impacted.

Don't worry about APW's you can add those (11 / db is probably too many anyway) BIW & AIW are the issue because you will only get 1. This causes an issue with Buffer Waits during heavy processing. We had problems with pauses at checkpoints, until we switched to directio. We had 16kb bi blocksize and 128mb clustersize and we were checkpointing every 40 seconds or so.

Also if a large table is read alot instead of flushing the memory for 1 of the 2 databases, you will flush the memory of the merged database. We saw a lot of contention on the LRU latch. 10.2B and the -B2 parameter may help with that.

The other issue may be applying schema changes. Instead of being able to update each database at the same time, you have to apply all your changes to a single schema. This is a problem if you need to add indexes to large tables.


For our situation, it made sense to merge into a single db - I'm not sure I would bother merging 2 into 1.
 
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