Function
Defines the size, in number of pages, of the data page cache in the database
(data pages kept in memory).
The actual amount of memory the page cache will use depends on the
following:
- The size of the cache, configured with the
derby.storage.pageCacheSize property.
- The size of the pages, configured with the
derby.storage.pageSize
property. Derby automatically
tunes for the database page size. If you have long columns, the default page
size for the table is set to 32768 bytes. Otherwise, the default is 4096
bytes.
- Overhead, which 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).
The minimum value is 40 pages. If you specify a lower value,
Derby uses the default
value.
