I have done this on both sides and the DB side is much much faster. I have big data modeling app (35 million transactions across 20 tables) with DB procedures and a big ETL app that has to exist and run on the MSoft client side. The DB is much much faster.

5 million is not very big. Typically tables are indexed to make retrieval quick. Further there are other DB features such as partitioning that would allow the table to appear as one large table but the DB would actually store the table and its indexes in seperate partitions based on some attrubute, likely, in your case, a user id or more likely a set of user ids. Retreival would then only look at the index and table partitions for the individual user or set of users. Keep an open mind, I think your strong view that separate databases increase performance is miss placed. We have done a exercise of consolidating 50+ databases each with 30,000+ tables and 10 of millions of rows in some tables. Same harwdare and the performance gain was about 3 times, administration effort cut 3 fold. The memory and CPU requirements just to start a single DB is considerable, consolidating allows these resource to be better utilized and boosts performance. There is also the idea that each user could be contained in a schema within a single DB, this is a half measure though as will you would gain performance, administration would still be high. I would encourage you to try a proof of concept with a single table on 10-30 DBs shut down those DBS and compare it to the combined verion of the table on one DB with all the resources from the 10-30 DBS allocated to single DB. The single DB is typically dramatically faster.

Sounds like you want to round your result to 2 decimal places before dividing by 100 SELECT (2/500)* 100 AS not_rounded, (round(2/500,2))* 100 AS rounded from dual; returns NOT_ROUNDED ROUNDED ----------- ------- 0.4 0

Regrads

I am wondering about your concerns about consolidating to a single large database. What are the largest row counts for your 30 tables for the biggest user? Database consolidation would seem to be a very attractive option, unless the numbers are extremely large. I suspect your may actually be losing performance by having seperate databases. A DB instance has a considerable base overhead and you are decreasing the available resources by that amount for each user you have. Further, the simplifacation in administration would be considerable.

Regards Nicholas Swandel