Hi Cedric,
Thanks for responding. On the second issue (the pre-caching),
I was thinking it would be created on deployment and be some sort
of configurable LRU managed by the DBMS.
About the competing process consideration. Suppose I *knew* that no
non-appserver process would modify my CMP table. Couldn't I have a
low-maintenance bitmap replicated in the cluster. This bitmap would tell me
the status of the CMP tables so that I could simply check the bitmap (n x n
binary matrix) before my load went to the db? I would try to argue much on
this because I know there are probably many proprietary optimizations in
place that would nullify this benefit.
Thanks,
John
>From: Cedric Beust <[EMAIL PROTECTED]>
>Reply-To: Cedric Beust <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: Re: Are Entity Beans(CMP/BMP) really necessary???
>Date: Mon, 25 Jun 2001 09:20:09 -0700
>
>Hi John,
>
> > From: A mailing list for Enterprise JavaBeans development
> > [mailto:[EMAIL PROTECTED]]On Behalf Of John Harby
>
> > Thanks for responding Winston. I think the local interface addition in
>the
> > current draft handles the networking issues. The remaining
> > bottleneck is the database access. Repetitive db calls via ejbLoad and
>ejbStore are
> > a big hit.
> > BEA has tried to address this with some of their own extensions such as
> > specifying the database as exclusive so that it is assumed no other SQL
> > aside from the container will hit the CMP tables. But this is not
>usually
> > useful since most environments will have several applications
> > accessing the db. What I was suggesting was taking this to a smaller
>granularity and
> > allowing an individual CMP DD to specify that the table for the CMP was
> > exclusive (not the entire database).
>
>If an Entity bean doesn't have exclusive access to the database, there can
>be two scenarios:
>
>a) the competing process is another server in the same cluster
>b) the competing process is something that has nothing to do with EJB
>
>It seems to me that when people use db-is-shared=true, it's predominantly
>because of scenario a). And in that case, the other process will obviously
>be competing for access to the same table since it is an identical Entity
>bean.
>
>Your suggestion would only be an improvement for b), which I think only
>represents a minority, but it's just my opinion.
>
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