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Re: [eclipselink-users] caching query results for all queries...? 
sorry. I misunderstood the question.
To clear the full set of query results you'll have to call some EclipseLink native API - i.e. there is no JPA hint.
Unwrap the query using JpaHelper.getDatabaseQuery(Query), cast it to a org.eclipse.persistence.queries.ReadQuery and call: clearQueryResults(AbstractSession session). You can get the session using the JpaHelper API as well. 

-Tom

On 12/03/2012 11:56 AM, Tim Martin wrote:

mmm, but I think that only refreshes the results for the returned objects  ?  Is
that a correct assumption ?

it wouldnt remove all results for all param values from the cache for that named
query - meaning that the caller thats creating the named query would need to
know to force a refresh - but it doesnt know as its not responsible for doing
the updates...

our current scenario is :
static data updated generically in one ejb

when real business processing logic needs to get a piece of static data it's
read by entity specific dao's

when a static data entity is updated I want to clear the caches (I'm happy to
completely clear all caches at this point as it's very infrequent).
so I was hoping to call a short helper function that would do that - initially
by calling something like this here which would invalidate everything

genericUpdateDao.clearQueryCaches(){
     List<String>  qNames = Helper.getCachedQueryNames();
     for each qName {
         Query q = em.createQuery(qName)
         q.query.setHint("eclipselink.query-results-cache.size",1)
         q.getResultList();
}



On 12/03/2012 15:38, Tom Ware wrote:

I suggest you use the refresh query hint.  That should refresh the cache.

On 12/03/2012 11:09 AM, Tim Martin wrote:

Is there anyway to force a cache clear - I can see that

query.setHint(""eclipselink.query-results-cache.size",1)

and then calling the query with parameters that would never return a result
would clear the cache, BUT is there a better way ?


On 12/03/2012 13:12, Tom Ware wrote:

The query cache will not know to refresh when a different persistence
operation changes one of the results held in the cache.

-Tom

On 12/03/2012 4:58 AM, Tim Martin wrote:

Tom - one further question re queryResults caching -

if I run queryA which returns object X,Y,Z which are cached
and then and update one of those objects, does the query results cache know or
get told enough to clear the results for queryA so re running it will go to
the
database instead of returning a stale result ?

thanks

http://wiki.eclipse.org/Introduction_to_EclipseLink_Queries_%28ELUG%29#How_to_Cache_Query_Results_in_the_Query_CacheHow


to Cache Query Results in the Query Cache

In addition to EclipseLink's object cache, EclipseLink also supports a query
cache. There is the following distinction between the two:

  * The /object cache/ indexes objects by their primary key, allowing primary
    key queries to obtain cache hits. By using the object cache, queries that
    access the data source can avoid the cost of building the objects and
their
    relationships if the object is already present.
  * The /query cache/ is distinct from the object cache. The query cache is
    indexed by the query and the query parameters–not the object's primary
key.
    This allows for any query executed with the same parameters to obtain a
    query cache hit and return the same result set.



On 09/03/2012 14:14, Tom Ware wrote:

The hint can be added to all queries. Obviously it will improve performance
more for queries that are executed more often. (named queries are a good
candidate here)

Queries are actually cloned before we apply query hints to them, so the
SessionCustomizer option listed below may be what you want for certain
queries. (since it will affect the query every time it is looked up rather
than just the instance you get from em.createQuery()).


BTW: Some doc:

http://wiki.eclipse.org/Introduction_to_EclipseLink_Queries_(ELUG)#How_to_Cache_Query_Results_in_the_Query_Cache




-Tom

On 09/03/2012 8:49 AM, Tim Martin wrote:

Just to check - the hint can only be added to named ? not those built on
the fly
(which of course we are doing are best to avoid :)



On 09/03/2012 13:45, Tom Ware wrote:

There is no setting to do this universally for a whole persistence unit. It
should be possible to do this using EclipseLink-native API in a
SessionCustomizer by iterating through the queries defined in the query
manager and calling the required native API to set it up. The timeouts
could
be set in the same code.

The reason there is no universal setting is that it is not clear that this
would be desirable in most use-cases. EclipseLink already has a cache that
provides quite a bit of performance boost and the query results cache is
intended to provide an additional performance boost for selected queries.
Using the query cache requires an understanding about the degree to which
results may be stale when they come back.

-Tom

On 09/03/2012 8:16 AM, Tim Martin wrote:

Hi - anyone know if there is a valid property to use in the
persistence.xml to
cache all query results by name and parameter values.
So rather than putting a hint on the queries we can do something like

<property name="eclipselink.query-results-cache" value="true"/>


I've come across it searching in google - but not come across anything
defintive...

If so - how would we configure expiration of the cache ? something simple
like
expire everything every x minutes would do to start with..

Thanks
Tim


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