I was busy with something else, so couldn’t reply …

The issues was avg -10 4031 per day and all the errors were only in subpool 1 only.We configured 4 subpools in shared pool.

while checking the memory consumption in shared pool , came across this fixed component “db block buffers headers” consuming significant amount of memory almost 20%, in shared pool.This component got initiated because of db_block_buffers setting, so after few tests , observed that if we replace db_block_buffers with db_cache_Size , we can get rid of this component , allowing that memory for user programs.

Permanent allocations and chunks which happen to be in use (pinned) at the flush time, are not flushed out.

So its ok to see some components still take as much memory as they were taking…

I just came across another question while doing some research related to flushing shared pool. I did flush the shared pool and after a while I executed below query,

select inst_id,’shared pool’,ksmssnam, sum(ksmsslen) from x$ksmss
where ksmsslen>1
group by inst_id, ’shared pool’, ksmssnam;

I thought flushing out the shared pool will reset all the statistics but it didn’t so is it normal behavior or should it flush out?

Thanks!

Both v$sgastat (or my sgastatx script which uses x$ksmss) and also shared pool heapdumps/x$ksmsp should show “db_block_buffers” – a component *held in shared pool* if old fashioned memory management is used (9i only I think).

But I’d be interested in hearing your approach, Santosh.

Tanel,
Sorry for putting a question for someone else on your Blog.

If you remember I was trying to resolve the shared pool fragmentation problem by reducing the number of subpools from 4 to 2.But then I found a few weired thing in shared pool i.e. db block buffers headers consuming lot of space so I replaced it with db_cache_size and this component got removed from the shared pool and I also reduced the shared pool min size alloc to solve this issue.

thanks,
Santosh

With Regards.
Zafar

Excellent note.

Thanks a lot , again for sharing this wonderful research to the Oracle community of the world.

You are doing a great service to all of us.

Personally, also as a part of Oracle users of the world, I am feeling indebted to you .

Best regards,

amalendu.