设置Derby缓存优化查询性能

derby.storage.pageSize

Function

Defines the page size, in bytes, for on-disk database pages for tables or indexes used during table or index creation. Set this property prior to issuing the CREATE TABLE or CREATE INDEX statement. This value will be used for the lifetime of the newly created conglomerates.

Valid conglomerates

Tables and indexes, including the indexes created to enforce constraints.

Default

Derby automatically tunes for the database page size. If you have any LONG VARCHAR, LONG VARCHAR FOR BIT DATA, BLOB, or CLOB columns, or if Derby estimates that the total length of the columns declared at create time is greater than 4096 bytes, the default page size for the table is set to 32768 bytes. Otherwise, the default is 4096 bytes.

Valid values

Page size can only be one of the following values: 4096, 8192, 16384, or 32768 bytes. If you specify an invalid value, Derby uses the default value.

Example

-- changing the default for the system
derby.storage.pageSize=8192
-- changing the default for the database
CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(
'derby.storage.pageSize',
'8192')

Dynamic or static

This property is dynamic; if you change it while Derby is running, the change takes effect immediately. For information about dynamic changes to properties, see Dynamic and static properties.

例如：

CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(
'derby.storage.pageSize',

'32768');

CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(

'derby.storage.pageCacheSize',

'50000');