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Re: [eclipselink-users] Duration of a simple object query
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Hello,
With the setting CheckCacheThenDatabase, you are telling EclipseLink to
search its cache before going to the database. As you've seen, if the
object is in the cache, you will get much better performance since it
avoids the database hit. But when the object isn't in the cache, the
70ms will be a combination of a full cache search, a database hit and
building the object from the results. The only other option that might
help is to avoid the initial cache search, using DoNotCheckCache
instead. This will force all non-pk queries to go the database
directly, avoiding some of the delay when the objects do not exist in
the cache. Because it is a trade off, its up to your usage patterns to
tell if skipping the cache check when the objects are not there is worth
the cost of going to the database when the objects are in the cache.
Best Regards,
Chris
Holger Rieß wrote:
My query
...
Query query = em.createNamedQuery("findStockTableByItemNumber");
query.setParameter("itemnumber", itemNumber);
retStockTable = (Stocktable) query.getSingleResult();
...
needs about 15 ms if there is a record in the database and about 70 ms if there is no record (profiler).
The named query is ...
@NamedQuery(name = "findStockTableByItemNumber", query = "SELECT st FROM Stocktable st WHERE st.itemnumber = :itemnumber AND st.dataset = 'DAT' AND st.cKatalog = '001'", hints = {
@QueryHint(name = QueryHints.CACHE_USAGE, value = CacheUsage.CheckCacheThenDatabase),
@QueryHint(name = QueryHints.QUERY_TYPE, value = QueryType.ReadObject) }),
...
About 40% of my queries have no result - this is a great problem for the performance of my application.
There is no additional code for the handling of NoResultException.
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