On 9/8/14 10:15 AM, Raffaele Sgarro wrote:
Database encryption turned out to be the performance bottleneck of my
application. Running the same queries on the same data gives very
different figures when the database is encrypted. Since I must keep
the data encrypted on disk, I thought I could avoid the decryption
overhead by increasing the page cache and warming up the cache by
loading tables and indices at application startup. Virtually, I want
to run queries against in-memory tables and indices. I run the Derby
network server in its own dedicated VM process, gave the JVM 1GB of
heap, and configured 400MB of page cache (4KB page size * 100K pages),
database backup being 200MB.
The performance gain is really impressive (as expected) once the cache
has been warmed. Unfortunately, a quick test showed there must be lots
of cache misses with real usage patterns. I wonder if it's simply a
matter of sizing the cache (but how can 200MB of db not fit into 400MB
of memory?
Hi Raffaele,
It sounds as though your database fits in that page cache. Otherwise you
wouldn't see good performance on a warmed up cache. Could you clarify
what's not working as expected?
Thanks,
-Rick
Are record compressed on disk?), or if it doesn't work the way I
think, and I should use a cache at the application level (that maybe
I'll do anyhow, but if it workd, it'd be a big win for us)
Raffaele
