Hi Colin,
Cayenne internal cache state is in no way related to the connection
state - it can survive closing connections, etc. If you are connecting
to a separate DB process, Cayenne cache management techniques (as
mentioned by Marcin, and what you found in the docs), is the only
thing you need to know.
Embedded DB's add a whole other dimension to that by keeping committed
data in memory at the driver level - something Cayenne is not aware
of. So anything you do with "clearCache" or RefreshQuery, etc.,
affects Cayenne cache, and not the embedded DB JDBC layer. So here
you'd need to read the embedded DB docs (is that Derby, HSQL, H2?) and
see what they recommend to do in such situation. There maybe a SQL
query that would shutdown/reopen the file, or something else (like
restarting the DataSource).
Andrus
On Apr 1, 2008, at 4:13 AM, Colin Bankier wrote:
Thanks Andrus - but shouldn't something like getQueryCache().clear()
at least
clear any cache so that cayenne will retrieve the data fresh from
the DB
once the file has been overwritten? (Even if the connection isn't
closed
properly while this is happening.) This doesn't seem to be having any
effect.
I've also tried to look at the CAY-632 RefreshQuery, or
context.invalidateObjects(), but really wanted to refresh the whole
cache -
not just a particular collection of objects. Perhaps I just need to
know how
to use these correctly.
Any suggestions on how to do this would be greatly appreciated.
Cheers,
Colin.
Andrus Adamchik wrote:
Cayenne itself works with a DataSource. All connection management and
starting and stopping the embedded DB is deferred to the DataSource
and is beyond Cayenne scope. The default DataSource implementation
pools connections. If you need a different policy, you need to
provide
a DataSource that does whatever is appropriate in your environment.
Custom DataSource is installed by providing a special
DataSourceFactory for a give DataNode in the Modeler.
Andrus
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