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From: Aristedes Maniatis <ari@ish.com.au>
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Subject: Re: 3.0 cache documentation
Date: Thu, 14 May 2009 09:19:27 +1000
References: <86C2117E-94F8-4B8A-B6B3-DB51B0850C44@objectstyle.org>
 <ee04ee7f0905130628q7a2cb554xbd4f6c2485727435@mail.gmail.com>


On 13/05/2009, at 11:28 PM, Borut Bol=C4=8Dina wrote:

> Now a question. Let's say I create a select query on paintings with =20=

> OSCache
> cache group paintings. Lets say there are 3 paintings: p1, p2 and p3.
>
> Now they are cached in object cache and in separete query cache? Two =20=

> cache
> entries?

Correct. Two different types of cache.

> Let's say I create another painting and insert it into the db. The new
> painting p4 is now in object cache. If I want to have fresh list of
> paintings, I now have to invalidate the paintings cache group in the
> onCommit callback function.

If you way you fetch that list is through another query on the current =20=

context, then yes, you need to invalidate the query cache.

> Is there an alternative, like simply adding this
> p4 to cache group paintings?

You can't do that. But you can maintain your own List of paintings and =20=

add the new one to that. Remember that Cayenne does no in-memory =20
evaluation of the query so it cannot know whether your new painting =20
belongs in the list of (say) paintings starting with "A".


> If not, will the subsequent fetch contact the db for all p1-p4 or is =20=

> there a
> way that paintings will get fetched from object cache if they are =20
> there? I
> want to avoid reading (tens of)thousands of rows because =20
> occasionally some
> get inserted.

 =46rom Andrus' previous reply, the fresh query against the db will read =
=20
in all the relevant objects and replace them in the object cache. So =20
effective the object cache is used for following relations, but not =20
when performing a fresh query against the db.

Ari


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