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From "Godschall, John" <JGodsch...@firstmarblehead.com>
Subject [No Subject]
Date Fri, 02 Sep 2011 17:12:51 GMT
My application (Anthillpro) is currently Apache Derby -  I am looking at various
ways to improve performance.

I would like to try setting the following property and am looking for some assurance from
experienced users that there will be no ill affect.
Any comments would be much appreciated.


Defines the size, in number of pages, of the database's data page cache (data pages kept in
The actual amount of memory the page cache will use depends on the following:

  *   the size of the cache (configured with this property, derby.storage.pageCacheSize)
  *   the size of the pages (configured with the derby.storage.pageSize<http://db.apache.org/derby/docs/10.2/tuning/rtunproper40688.html#rtunproper40688>
  *   overhead (varies with JVMs)

When increasing the size of the page cache, you typically have to allow more memory for the
Java heap when starting the embedding application (taking into consideration, of course, the
memory needs of the embedding application as well). For example, using the default page size
of 4K, a page cache size of 2000 pages will require at least 8 MB of memory (and probably
more, given the overhead).

For a simple application (no GUI), using the Sun 1.1.7 JVM on Windows NT and using the -mx96m
option (which allows 96 MB for the Java heap), it is possible to have a page cache size of
10,000 pages (approximately 40 MB).

The minimum value is 40 pages. If you specify a lower value, Derby uses the default value.

John Godschall
Release Engineer | First Marblehead
781.658.5028 (direct)
617.513.1912 (mobile)
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