Hi Joe,
Assuming 2000 products fetched with a paginated query and a page size
of 50, I believe the answers are ...
Q1: 2000 hollow objects are created. Cayenne fetches the primary
keys of the objects first in a paginated query.
Q2: Whichever page (or pages) you access in the paginated list will
fault those objects for that page (grouped by 50 at a time) into
memory.
Q3: If you try to filter or sort in-memory, then it will have to fetch
all of the objects. Might be better to re-issue a query to the DB.
Q4: If your list pointers go out-of-scope, but the DataContext is
still in-scope, then the objects will still be in the DataContext
until you evict them.
mrg
On Thu, Apr 8, 2010 at 4:24 PM, Joe Baldwin <jfbaldwi..arthlink.net> wrote:
> Andrus,
>
> In this same context, I have a question about what behavior I should expect to see.
>
> Let us assume for this scenario:
> 1. a web deployment with Tomcat, typical webstore pattern
> 2. 2000-5000 products with an attribute "name"
> 3. custom search engine built on top of cayenne
> a. mostly standard configuration
> b. set PageSize to 50
> c. using (presumably) default caching
> d. custom factory class method used to create a select query
> 4. a user searches for "guitar" substring in the name field
>
> Questions:
> 1. Based on my tests, it appears that "hollow" objects are created but no faults are fired. (true?)
> 2. If I display any product data for a subset less than PageSize, then only <PageSize> number of objects are faulted (true ?)
> 3. If I execute "filterObjects" or "orderList" on the resulting list, I assume the fault is fired for all objects in the list. (true ?)
> 4. What normally happens to these objects if my list pointers go out of scope? (Are they GarbageCollected per Java rules?)
>
> (Note: I have not been able to get much visibility in understanding (3) & (4), but I think my tests show that 1 & 2 are correct.)
> Joe
>
>
>
>
> On Apr 8, 2010, at 12:42 PM, Andrus Adamchik wrote:
>
>> BTW, we started on some monitoring hooks inside Cayenne runtime in 3.0 per http://issues.apache.org/jira/browse/CAY-1173 , however then it was decided that it'll work much better with the 3.1 DI-based stack. So this is waiting for its time.
>>
>> Andrus
>>
>>
>> On Apr 7, 2010, at 6:16 PM, Joe Baldwin wrote:
>>
>>> I am attempting to do more performance monitoring (with an eye towards optimizing my design & use of DataObject lists and lifetime).
>>>
>>> The first thing I would like to do is monitor how many DataObjects are created and which JSP session they belong.
>>>
>>> My idea was to simply create a constructor for the DataObject of interest and place monitoring hooks inside. I would assume that I could also create a finalize method to do similar things.
>>>
>>> Is this the best way to create custom monitoring using Cayenne DataObjects or is there a better way?
>>>
>>> (BTW, even after reading the docs, I am still somewhat mystified by how my configuration specifications control the life cycle and performance. So I am hoping these custom hooks will make my design decisions more visible, especially with multiple users.)
>>>
>>> Thanks,
>>> Joe
>>>
>>>
>>
>
>
This archive was generated by hypermail 2.0.0 : Thu Apr 08 2010 - 17:19:18 EDT