The SQL repository maintains separate item caches and query caches for each item descriptor. This lets you size and flush caches separately for separate item types. You can configure these caches using the following attributes in an <item-descriptor> tag:
item-cache-size | The maximum number of items belonging to this item descriptor to store in the item cache. When the number of items requested exceeds this number, the least recently accessed item is removed from the cache. | Integer. Default is 1000. |
query-cache-size | The maximum number of queries of this item descriptor to store in the query cache. When the number of queries issued against this item descriptor exceeds this number, the least recently used query is removed from the cache. | Integer. Default is 0, effectively disabling the query cache. |
item-expire-timeout | The maximum time in milliseconds that an entry can remain in the item cache before it is refreshed. See Cache Timeout for more information. | Integer. Default is -1, which means items remain in the cache indefinitely, until otherwise invalidated. |
query-expire-timeout | The maximum time in milliseconds that an entry can remain in the query cache before it is refreshed. See Cache Timeout for more information. | Integer. Default is -1, which means items remain in the cache indefinitely, until otherwise invalidated. |
item-cache-timeout | The time in milliseconds that an item cache entry can remain unused before it is removed from the cache. See Cache Timeout for more information. | Integer. Default is -1, which means items remain in the cache indefinitely, until otherwise invalidated. |
Note that the query cache and item cache sizes are set by default is 0, effectively disabling the caches. This is an appropriate setting for evaluation and development; for testing and deployment, you need to set these caches to more appropriate values. Assuming you have realistic testing scripts, you may be able to estimate reasonable cache sizes during testing, using the feature described in the Cache Statistics section of this chapter.
