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From Jeff de Vries <>
Subject Re: Caching problem?
Date Sun, 21 May 2006 18:49:29 GMT
Okay, assuming I did this correctly it is still showing the old status.  
I had to remove the Configuration.initializeSharedConfiguration() line 
because it seemed to be messing things up so it couldn't find 
cayenne.xml, etc.  Note that at the point I'm calling this there already 
is a shared configuration that was set up by the standard Cayenne web 
filter, so I'm assuming it is still okay to use that one, and just 
create a new data context.

Thanks again!

Marcin Skladaniec wrote:
> On 20/05/2006, at 2:25 PM, Jeff de Vries wrote:
>> Named queries? - No (is there a problem with named queries?)
> There is no problem with named queries. I was asking, as those queries 
> are (I think) cached by default.
>> Same context? - Maybe.  This is a web app, and the alert is created 
>> during one http request, while the check is on a subsequent http 
>> request.  Since the data context is being bound to the thread, it 
>> would depend on whether the same thread handled both requests.  How 
>> can I create a new (different) data context if I want to make sure it 
>> is different than the original data context?  BTW, this problem is 
>> repeatable, so if the problem is using the same data context, then it 
>> would appear that the same thread is being used for both http requests.
> To create new context :
>     Configuration.initializeSharedConfiguration();
>     Configuration conf = Configuration.getSharedConfiguration();
>     dataDomain = conf.getDomain();
>     dataContext = dataDomain.createDataContext();
> Let me know how it goes.
> Marcin
>> Marcin Skladaniec wrote:
>>> I'll ask few questions, just to be sure:
>>> - are you using named queries (ie. when fetching the alerts)
>>> - are you using the same context when creating alert and when 
>>> checking for the alerts ?
>>> If the latter try to use different context. And to be 100% sure in 
>>> the second query do query.setCachingPolicy(SelectQuery.NO_CHACHE);
>>> See if that helps.
>>> Regards
>>> Marcin
>>> On 20/05/2006, at 11:35 AM, Jeff de Vries wrote:
>>>> It didn't make any difference.  (I was so sure it *would* make a 
>>>> difference I ran it three times and double-checked everything each 
>>>> time).
>>>> Looking at the SQL log, it looks like I oversimplified the 
>>>> description of the problem (sorry).  There is actual another table 
>>>> involved, Listing, and the status that is being updated is in 
>>>> Listing, not in Alert, though the Listing is being accessed through 
>>>> the Alert (Alert has a foreign key referencing the Listing).  So, 
>>>> let me try again to describe the sequence of steps that are used to 
>>>> update the database:
>>>> 1)  Using a given Listing, we SELECT all Alerts that refer to that 
>>>> Listing. (In the case I'm looking at there is only one Alert).
>>>> 2)  Start transaction (i.e. there is a (unnecessary?) commit after 
>>>> the previous SELECT)
>>>> 3)  INSERT a new Alert that references the existing Listing (note 
>>>> that at this point the Listing has not been updated yet, i.e. it 
>>>> still has the old status) and the Person the Alert is addressed to.
>>>> 4)  UPDATE the first Alert to indicate it has been processed (i.e. 
>>>> set a 'seen' column to 'true')
>>>> 5)  UPDATE the status in the Listing to the new status (this is the 
>>>> thing we're seeing the old version of later)
>>>> 6)  COMMIT changes.
>>>> Later, we do the following:
>>>> 1)  SELECT all Alerts addressed to this Person (which includes the 
>>>> new Alert created in step 3 above; this is also the query to which 
>>>> we added setRefreshingObjects = true, which now looks unnecessary 
>>>> since we did get the new Alert even before making that change)
>>>> 2)  For each Alert, display the status of the Listing referenced by 
>>>> that Alert.  Note that at this point in the SQL log I don't see any 
>>>> SELECT statements trying to retrieve Listing data, so I'm guessing 
>>>> Cayenne thinks it already knows all the associated Listings and 
>>>> their statuses.  It looks like it is the relationship between Alert 
>>>> and Listing that needs to be refreshed?
>>>> 3)  The status for the Listing associated with the new Alert still 
>>>> shows the value it had before it was updated in step 5 above.
>>>> So, is it possible that when the new Alert is created it is 
>>>> pointing at the original version of the Listing (I'm talking about 
>>>> the in-memory objects, not the rows out in the database), but when 
>>>> the Listing is updated the in-cache version isn't getting updated?  
>>>> Or the in-cache version is getting updated, but the Alert is 
>>>> pointing at a stale Listing object?
>>>> Thanks for the help!
>>>> Jeff
>>>> Marcin Skladaniec wrote:
>>>>> You can try:
>>>>> DataContext dc = DataContext.getThreadDataContext();
>>>>> SelectQuery query = new SelectQuery(alert_subclass);
>>>>> ...
>>>>> query.setRefreshingObjects(true);
>>>>> ...
>>>>> List result = dc.performQuery(query);
>>>>> Regards
>>>>> Marcin
>>>>> On 20/05/2006, at 8:05 AM, Jeff de Vries wrote:
>>>>>> I get the following compile error (I'm using Cayenne 1.2):
>>>>>>   The method performQuery(Query) in the type DataContext is not 
>>>>>> applicable for the arguments (SelectQuery, boolean)
>>>>>> I tried to find something equivalent for Cayenne 1.2 but didn't 
>>>>>> recognize anything.
>>>>>> Gentry, Michael (Contractor) wrote:
>>>>>>> Could you try: List result = dc.performQuery(query, true); And

>>>>>>> see if it works better? Thanks, /dev/mrg -----Original 
>>>>>>> Message----- From: Jeff de Vries []

>>>>>>> Sent: Friday, May 19, 2006 12:18 PM To: 
>>>>>>> Subject: Re: Caching problem?

>>>>>>> It's pretty straightforward. In the following code Person is
>>>>>>> parent, and Alert is the child. There are actually many Alert

>>>>>>> classes (I'm using Cayenne STI), so the specific Alert class

>>>>>>> we're interested in is passed as a parameter. Also, I forgot
>>>>>>> mention that if we shut everything down, and then restart, we
>>>>>>> see the modified status (presumably because Cayenne really had

>>>>>>> to go back to the database to get the data for the child list).

>>>>>>> /** * Finds all Alerts of the given type sent to the given 
>>>>>>> person * * @param person * Person to find Alerts for * @param

>>>>>>> include_hidden * If true, include hidden alerts as well * @param

>>>>>>> alert_subclass * Class of alert to search for * @return List
>>>>>>> alert objects, of given type, for the given person */ protected

>>>>>>> static List findFor(Person person, boolean include_hidden, Class

>>>>>>> alert_subclass) { DataContext dc = 
>>>>>>> DataContext.getThreadDataContext(); SelectQuery query = new 
>>>>>>> SelectQuery(alert_subclass); 
>>>>>>> query.setQualifier(ExpressionFactory.matchExp("toReceiver", 
>>>>>>> person)); 
>>>>>>> query.andQualifier(ExpressionFactory.matchExp("deleted", new

>>>>>>> Boolean (false))); if (!include_hidden) 
>>>>>>> query.andQualifier(ExpressionFactory.matchExp("hidden",new 
>>>>>>> Boolean (false))); query.addOrdering("createDate",false); List

>>>>>>> result = dc.performQuery(query); return result; } On May 19,

>>>>>>> 2006, at 6:05 AM, Gentry, Michael ((Contractor)) wrote:
>>>>>>>> Jeff, could you post the code where you are doing the second

>>>>>>>> query? Thanks! /dev/mrg -----Original Message----- From:
>>>>>>>> de Vries [] Sent: Friday, May 19,
>>>>>>>> 12:09 AM To: Subject: Caching

>>>>>>>> problem? Simplified version: I have a parent table and a
>>>>>>>> table, where the child table has a parent_id column and a

>>>>>>>> status column. I change the status in one of the child records

>>>>>>>> and commit the change. Later, I ask for the child records
>>>>>>>> the given parent record, but the child record that I get
>>>>>>>> on which I changed the status still has the *old* status

>>>>>>>> instead of the new status. If I look at the database, the
>>>>>>>> record does have the new status (and in fact I can see the

>>>>>>>> update and commit as soon as I commit the child record change).

>>>>>>>> Why is the parent still seeing the old child status? An 
>>>>>>>> additional note is that I'm not using parent.getChildArray()

>>>>>>>> but rather a SelectQuery(Child) that matches toParent to
>>>>>>>> parent I'm interested in. (This is in Cayenne 1.2B2 using

>>>>>>>> PostgreSQL 8.1) Thanks, Jeff

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