On 31/03/12 3:06 AM, Bruno René Santos wrote:
Hello all,
I am using now Cayenne 3.1M4 Snapshot and first let me just say that its
performance is much better than 3.0.1 (How did you do it? just curious) but
I am having a strange problem.
I am creating a web application with popups as item detail
Hi Michael,
I just looked up the def of Optimistic Locking and it forwarded me to
Optimistic Concurrency Control (so I am not sure of the distinction just yet).
But I *think* that the behavior that I have seen in my webapp would be your
implementation of optimistic locking.
RE: "As for faulti
Hi Joe,
It mainly sounds like you care about optimistic locking. Cayenne can
use whichever columns you select to test for external changes upon an
UPDATE. As for faulting data into memory, Cayenne will get the
freshest data the DB has at that point, excluding any pending
transactional changes.
Hello all,
I am using now Cayenne 3.1M4 Snapshot and first let me just say that its
performance is much better than 3.0.1 (How did you do it? just curious) but
I am having a strange problem.
I am creating a web application with popups as item details where I use
child contexts in order to able to
Hi Sheldon,
I guess I don't understand why you can't specify a page size (say 100
or 1000) on your query (unless you are getting the list of PKs from an
external source), especially since you want actual Java objects in the
end.
mrg
On Fri, Mar 30, 2012 at 10:45 AM, Sheldon wrote:
> Hello Mich
OK, I am getting confused as to the subject that we are arguing. My interest
is specifically with the thesis and conclusion:
>>> Cayenne doesn't care about staleness. ... If data isn't available yet, just
>>> load it - and accept the risk that the application may now be working with
>>> partly
Let me try to think how to better present my point. I'll try to get back in a
few days.
On Mar 30, 2012, at 5:34 PM, Joe Baldwin wrote:
> Andrus,
>
> I am pretty smart, but I have NO idea what you just said, :) I would really
> like to understand your argument as it sounds like something tha
On Mar 30, 2012, at 5:37 PM, Durchholz, Joachim wrote:
>> You have to inflate your cache anew from DB in every transaction.
>> You don't have any data when you start.
>
> Sure, that's unavoidable if you want to do optimistic locking.
You can do optimistic locking with cached data just as well.
Hello Michael,
I want to use a SelectQuery (but without using of a String "select ...")
Thanks
Sheldon
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Hi Sheldon,
Is your list of PKs coming from an external source or are you wanting
to use a SelectQuery?
Thanks,
mrg
On Fri, Mar 30, 2012 at 9:28 AM, Sheldon wrote:
> Yes I mean primary key.
> For example I have a list of primary keys (that should not be random list
> keys) and I want to fetch
On Mar 30, 2012, at 5:01 PM, Durchholz, Joachim wrote:
>>> Thanks for explaining. If this is so, it sounds... unscalable.
>>
>> How so?
>
> You have to inflate your cache anew from DB in every transaction.
> You don't have any data when you start.
Sure, that's unavoidable if you want to do opti
Andrus,
I am pretty smart, but I have NO idea what you just said, :) I would really
like to understand your argument as it sounds like something that might be
important to my project. Do you have an analysis somewhere I read up on this?
Thanks
Joe
On Mar 30, 2012, at 10:12 AM, Andrus Adamc
On Mar 30, 2012, at 5:01 PM, Durchholz, Joachim wrote:
>> Thanks for explaining. If this is so, it sounds... unscalable.
>
> How so?
You have to inflate your cache anew from DB in every transaction. You don't
have any data when you start.
However I don't think you are right in your assessmen
> Thanks for explaining. If this is so, it this sounds... unscalable.
How so? At worst, the memory footprint doubles (plus maybe a logN factor), that
sounds pretty scalable to me. ("non-scalable" is "more than NlogN overhead" in
my book; I do not know of any substantially better way to implement
>> Cayenne doesn't care about staleness. It's the application's
>> task to ensure that Pojo networks are updated to the current
>> DB state at the beginning of an application-side transaction.
>> If data isn't available yet, just load it - and accept the
>> risk that the application may now be work
Thanks for explaining. If this is so, it this sounds... unscalable.
On Mar 30, 2012, at 4:45 PM, Durchholz, Joachim wrote:
>>> Hibernate strictly controls the staleness of objects. If a Session
>>> closes, the objects become detached and potentially stale, and
>>> there's no way to make the cur
>> Hibernate strictly controls the staleness of objects. If a Session
>> closes, the objects become detached and potentially stale, and
>> there's no way to make the current again (except by transferring
>> their contents to objects of a new Session). Hibernate goes to
>> great lengths to protect t
Hi Joe,
I've never benchmarked/explored it, but my hunch is the number of
pages would have to be pretty low (say, less than 3-5). Of course, if
you are trying to figure out in-memory vs hit the database again, that
logic just adds a bit more complexity to your code and is more to
maintain. I thi
About this comment:
On Mar 30, 2012, at 8:56 AM, Durchholz, Joachim wrote:
> Cayenne doesn't care about staleness. It's the application's task to ensure
> that Pojo networks are updated to the current DB state at the beginning of an
> application-side transaction. If data isn't available yet, j
Yes I mean primary key.
For example I have a list of primary keys (that should not be random list
keys) and I want to fetch the related objects of these keys.
Is this possible?
Sheldon
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Sent f
> Hibernate strictly controls the staleness of objects. If a Session closes,
> the objects become detached and potentially stale, and there's no way to make
> the current again (except by transferring their contents to objects of a new
> Session). Hibernate goes to great lengths to protect that
What I mean is,
if I have a Table with n columns (col1, col2, col3 ...) and want load only
the value ov col1 and col3 (without loading col2 and the others).
Is this example possible?
Sheldon
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S
OK, good analysis, that makes a lot of sense. So the thing to remember with
post-query ordering on large result sets: it is more efficient to re-submit the
query to the database.
At which point (presumably list size) do you think that orderList() becomes
reasonable to use on a result set?
Than
I agree the difference is the approach.
Hibernate strictly controls the staleness of objects. If a Session closes, the
objects become detached and potentially stale, and there's no way to make the
current again (except by transferring their contents to objects of a new
Session). Hibernate goes
Hi Joe,
I think you are on the right path using setPageSize() to limit the
result set, but even 50k results is a lot of PKs to return (although
not a ludicrous amount, depending on your users).
The first approach I would take is if they do a post-query sort then
send another query to the database
Hi Sheldon,
Like Andrew, I think you meant "primary keys" rather than "private
keys". I'm going to guess at what you really are trying to do, but I
may fail. :-)
You can have Cayenne fetch primary keys only instead of full objects
by using a paginated query:
http://cayenne.apache.org/doc30/pag
Not a JSF user myself, but the use of Cayenne is not that much different
between various frontends. You've probably seen the webapp Cayenne tutorial at
http://cayenne.apache.org/doc30/tutorial.html You can just follow that on the
Cayenne end. You will need to find a similar introductory resource
Hi Sheldon;
I think you mean "primary keys" rather than "private keys"?
I have recently (re)put some material I have written around Cayenne
(+more) online;
http://www.silvereye.co.nz/lestuff.html
You may find something ~similar~ to what you are looking for in;
LECayHelper.qu
Hello,
can I fetch data from db with a list of private keys? One possibility is to
do this with SQLTemplate and than create a SELECT statement.
But I want to do this like:
Cayenne.objectForPK(context, Class, List of PKs)
Sheldon
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