Re: Best way to inform (and handle cached object refreshing) of externally-updated database records?

From: Mike Kienenberger (
Date: Mon Nov 22 2004 - 11:29:44 EST

  • Next message: Andrus Adamchik: "Re: Best way to inform (and handle cached object refreshing) of externally-updated database records?"

    Andrus Adamchik <> wrote:
    > 1. Use Cayenne built-in remote notifications.
    > Good thing about snapshot
    > events is that you can tell the listener exactly which objects were
    > modified.

    Thanks. The batch job updates hundreds of thousands of account objects,
    most of which aren't used by my web application, so providing a list of
    which objects were modified is probably not a good strategy in this case.

    > 2. Continue using LAST_EXTERNAL_UPDATE and manually invalidate cache.
    > Here is one (but not the only) way to do that for just the shared
    > entities. For each "shared" entity create a named query in the Modeler
    > with Result Caching policy of "Shared Cache". Whenever you detect from
    > LAST_EXTERNAL_UPDATE that refresh is needed, you can do a refresh like
    > that:
    > 2a. Call "DateRowStore.cacheSnapshots("query_name", null) for each
    > "shared" query. This assumes that all your DataContexts access shared
    > object via such queries, and in no other way, and also that you don't
    > mind stale data in existing DataContexts.
    > or
    > 2b. Call DataContext.performQuery("query_name", true) for each shared
    > query. This will give you fresh objects immediately and as a side
    > effect refresh shared cache.

    The problem is that my account objects are loaded indirectly. I don't pull
    them in as a result of an explicit query, but only as the result of
    referencing a relationship getter method on other objects.

    Is there a way to handle this without using a shared cache?

    What about using


    to iterate through all objects (does the above get all objects or only
    objects registered to a particular DataContext?), and then invalidating all
    objects of a specific (in this case "account") class?

    I don't mind having stale data in existing datacontexts, so long as when new
    contexts are created via BasicServletConfiguration.getDefaultContext(), they
    have current data.


    This archive was generated by hypermail 2.0.0 : Mon Nov 22 2004 - 11:28:18 EST