Oracle Database Discussions

Hi,

I want to find an optimal DB_BLOCK_SIZE by running my tests against 4k,8k and 16k block sizes. I have studied one huge otn forum link regarding db_block_sizes but still I'm confused. I've not got much from that link.

So, I want to conduct my own tests for my research about finding an optimal db block size. I've few questions which I want to be sure before running my tests. So that later when I put my results here for expert opinions, tests should be proper tests and that I note proper things regarding my testing.

First of all is it ok to create 4k and 16k tablespaces in my 8k block size 11g (11.1.0.6.0) db or I've to create separate 4k and 16k databases. Does it matter or no difference whatever way is chosen?

Secondly, in case if i will have to create separate databases of 4k and 16k, do I also need to set db_file_multiblock_read_count? or what, if I do not need to create separate dbs. something like this:

2k block * 512 MBRC = 1MB
4k block * 256 MBRC = 1MB
8k block * 128 MBRC = 1MB
16k block * 64 MBRC = 1MB

to equalize the testing or Oracle itself will set value for db_file_multiblock_read_count.

Currently, db_block_size=8192 and db_file_multiblock_read_count=64

Thirdly, what things to consider for proper testing like ELAPSED TIME (that the query is faster in particular db_block_size) or anything else?

Thanks alot.

Regards