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JDO doesn't currently define a mechanism for caching of queries. DataNucleus provides
the following level of caching
-
Generic Compilation : when a query is compiled it is
initially compiled
generically
into expression trees. This generic compilation
is independent of the datastore in use, so can be used for other datastores.
This can be cached.
This cache is by default set to
weak
, meaning that the generic query compilation
is cached using weak references. This is set using the persistence property
datanucleus.cache.query.type
. You can also set it to
hard
meaning that strong references are used, or
soft
meaning that soft references
are used, or finally to
none
meaning that there is no caching of generic query
compilation information
You can turn caching on/off (default = on) on a query-by-query basis by specifying the
query extension
datanucleus.query.cached
as true/false.
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