Ashwin Jayaprakash wrote:
Hello,
I'm posting several questions about Perf tuning. I'd be grateful if
people can provide me with answers.
I'm using Derby as an Embedded Database for a prototype application,
where Derby is used to run queries on a small set of Rows, very
frequently. Rows are inserted into the Tables at very high rates. The
Queries are run on these new Rows and so they are hot, in the Cache.
Once the Query is executed on those Rows, they can be discarded. In a
sense, I want Derby to function as an in-memory DB, like Oracle TimesTen.
I've tuned all the documented parameters like PageCacheSize, PageSize
and Durability=test. Are there any other ways I can drastically reduce
the Commits to the Disk and thereby eliminate Disk IO? Perhaps rewrite a
key Class and add that to the "Pre-Classpath" so that the default
behaviour can be over-ridden?
I guess your problem may really be that you are not able to reuse the
pages used by old rows for new rows after the old rows have been
deleted. (I assume you delete your old rows.) If you could reuse
existing pages for new data, you would never have to replace pages in
the cache, and hence you would not be dependent on disk IO for
performance. (Assuming you combine this with durability=test).
--
Øystein
