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Avoiding N+One Selects and stale BatchValueHolders [message #666808] Fri, 22 April 2011 13:33 Go to previous message
Michael Mising name is currently offline Michael Mising name
Messages: 9
Registered: April 2011
Junior Member
I'm trying to cut down the number of n+1 selects incurred by my application, in as many places as possible I've tried to add the batch read hint to queries. In a large number of places in the app I don't always know exactly what relationships I'll be traversing (My view displays fields based on user preferences). At that point I'd like to run one query to populate all of those relationships for my objects.

My dream is to call something like ReadAllRelationshipsQuery(Collection,RelationshipName) and populate all of these items so that later calls to:

Collection.get(0).getMyStuff will already be populated and not cause a db query. How can I accomplish this? I'm willing to write any code I need to but I can't find a way that works with eclipselink?

-- Why don't I just batch read all of the possible fields and let them load lazily? What I've found is that the batch value holders that implement batch reads don't behave well with the eclipselink cache. If a batch read value holder isn't "evaluated" and ends up in the eclipse link cache it can become stale and return incorrect data (This behavior was logged as a bug by someone else but rejected...)

How do I avoid N+1 selects for objects/collections I already have a reference to?

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