You can implement preloading and reloading of data in your
application with a Java Persistence API (JPA) utility. This capability
can simplify loading the maps when the queries to the database cannot
be partitioned.
About this task
When you run a preload or reload operation on your map, the
following actions occur:
- The initial action that is taken depends on if you are running
a preload or reload operation.
- Preload operation: The map to be preloaded is cleared.
For an entity map, if any relation is configured as cascade-remove,
any related maps are cleared.
- Reload operation: The provided query is run on the map
and the results are invalidated. For an entity map, if any relation
is configured with the CascadeType.INVALIDATE option,
the related entities are also invalidated from their maps.
- Run the query to JPA for the entities in a batch.
- For each batch, a key list and value list for each partition is
built.
- For each partition, the data grid agent is called to insert or
update the data on the server side directly if it is an eXtreme Scale client. If the data
grid is a local instance, the data in the maps is directly inserted
or updated.