"Not enough memory" errors

[Brian Bientz]

Could you elaborate? When would it be advantagous to decrease the size of the SGA and why?

What should I not forget about DB Block Buffers?

[Satar Naghshineh]

Hi,

In regards to Database buffers, I meant that you should test the results of adding or decreasing the number of buffers. I believe the parameter was DB_BLOCK_LRU (I forget the utility/parameter needed to test DB Block Buffers).

In regards to having a large SGA, I asked the same question. Below is a partial response I received from Thomas Kyte (a top leader in the Oracle Database world):

I could speculate that the queries didn't ever re-use the data (the data was
never read twice, lots of reading going on but not lots of re-reading of data).
In this case, having lots of data in the cache and managing that would slow
things down (lots to manage and more to look through to discover that it isn't
already cached and you have to go to disk anyway).

I could speculate that the machine was swapping like crazy and need the ram
back.

Its not necessarily a good thing to cache entire databases. We are expecting,
and are optimized for, to have to go to disk sometimes. We have a feature
called the VLM (very large memory) for caching more (showing the the bigger the
cache, you need different algorithms to manage).

Regards,
Satar Naghshineh