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Posted to ojb-user@db.apache.org by Tino Schöllhorn <t....@tiscali.de> on 2004/02/13 18:33:44 UTC

Cache issue

Hi,

I have (again) something weird which I suppose is just a configuration 
problem:

I have a class Person which has one LONGVARCHAR-Field. The first time 
the object is accessed the LONGVARCHAR-field is returned correctly. But 
the second time it is accessed it returns just 256 (I suppose) characters.

I am using Access as 'database' but I don't think this is the problem.

Do you have any ideas what I could try?
Tino



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Re: Cache issue

Posted by Tino Schöllhorn <t....@tiscali.de>.
Hello Armin,

the data is correct in the database. But I now made another observation:

If the data is retrieved by:

Query query = new QueryByCriteria(Person.class, null);
		
return pb.getCollectionByQuery(query);

the resulting collection is correctly instantiated.

But if I use

Criteria crit = new Criteria();
crit.addEqualTo("id", myId);
	
Query query = QueryFactory.newQuery(Person.class, crit, true);
		
res = pb.getObjectByQuery(query);


I get the truncated data. So my first description wasn't quite correct - 
but something is very strange - in my opinion.

regards
tino

Armin Waibel wrote:
> Hi,
> 
> Tino Schöllhorn wrote:
> 
>> Hi,
>>
>> I have (again) something weird which I suppose is just a configuration 
>> problem:
>>
>> I have a class Person which has one LONGVARCHAR-Field. The first time 
>> the object is accessed the LONGVARCHAR-field is returned correctly.
> 
> 
> hmm, does this mean first time after creation? Which cache was used?
> Maybe first time after store it was found in cache, second time it was 
> read from DB. So I assume your "database" truncate the String on insert.
> Maybe I'm wrong ;-)
> 
> regards,
> Armin
> 
>> But the second time it is accessed it returns just 256 (I suppose) 
>> characters.
>>
>> I am using Access as 'database' but I don't think this is the problem.
>>
>> Do you have any ideas what I could try?
>> Tino
>>
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
>> For additional commands, e-mail: ojb-user-help@db.apache.org
>>
>>
>>



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Re: Cache issue

Posted by Armin Waibel <ar...@apache.org>.
Hi Tino,

I don't think that OJB is the problem (but maybe I'm wrong). The only 
difference between the Criteria is the 'distinct' flag. So I this Access 
has a problem with the distinct flag. Please enable p6spy to trace the 
generated SQL statements.
See
http://db.apache.org/ojb/faq.html#How can I trace and/or profile SQL 
statements executed by OJB?

How does the generated SQL for both Criteria look like?
Try to invoke these statements against your DB and compare the results.
If both statements return the same result ... OJB has a problem ;-)

regards,
Armin

Tino Schöllhorn wrote:
> Hello Armin,
> 
> I could pinpoint the described error. It all boils to the 
> QueryFactory.newQuery(Class, Criteria, boolean) method. if I execute the 
> code to retrieve an instance of class Person with:
> 
> Criteria crit = new Criteria();
> crit.addEqualTo("id", "85");
> Query query = QueryFactory.newQuery(Person.class, crit);
>        
> Collection c = pb.getCollectionByQuery(query);
> .... and so on
> 
> everything works perfectly and the instances of Person are instantiated 
> correctly. But if I use the method described in the first place:
> 
> Criteria crit = new Criteria();
> crit.addEqualTo("id", "85");
> Query query = QueryFactory.newQuery(Person.class, crit, true);
> 
> After that query the LONGVARCHARS aren't correctly instantiated.
> 
> I think that this might be an error of OJB.
> 
> With regards
> Tino
> 
> 
> 
> 
> 
> Armin Waibel wrote:
> 
>> Hi,
>>
>> Tino Schöllhorn wrote:
>>
>>> Hi,
>>>
>>> I have (again) something weird which I suppose is just a 
>>> configuration problem:
>>>
>>> I have a class Person which has one LONGVARCHAR-Field. The first time 
>>> the object is accessed the LONGVARCHAR-field is returned correctly.
>>
>>
>>
>> hmm, does this mean first time after creation? Which cache was used?
>> Maybe first time after store it was found in cache, second time it was 
>> read from DB. So I assume your "database" truncate the String on insert.
>> Maybe I'm wrong ;-)
>>
>> regards,
>> Armin
>>
>>> But the second time it is accessed it returns just 256 (I suppose) 
>>> characters.
>>>
>>> I am using Access as 'database' but I don't think this is the problem.
>>>
>>> Do you have any ideas what I could try?
>>> Tino
>>>
>>>
>>>
>>> ---------------------------------------------------------------------
>>> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
>>> For additional commands, e-mail: ojb-user-help@db.apache.org
>>>
>>>
>>>
> 
> 
> 
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> 
> 
> 

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Re: Cache issue

Posted by Tino Schöllhorn <t....@tiscali.de>.
Hello Armin,

I could pinpoint the described error. It all boils to the 
QueryFactory.newQuery(Class, Criteria, boolean) method. if I execute the 
code to retrieve an instance of class Person with:

Criteria crit = new Criteria();
crit.addEqualTo("id", "85");
Query query = QueryFactory.newQuery(Person.class, crit);
		
Collection c = pb.getCollectionByQuery(query);
.... and so on

everything works perfectly and the instances of Person are instantiated 
correctly. But if I use the method described in the first place:

Criteria crit = new Criteria();
crit.addEqualTo("id", "85");
Query query = QueryFactory.newQuery(Person.class, crit, true);

After that query the LONGVARCHARS aren't correctly instantiated.

I think that this might be an error of OJB.

With regards
Tino





Armin Waibel wrote:

> Hi,
> 
> Tino Schöllhorn wrote:
> 
>> Hi,
>>
>> I have (again) something weird which I suppose is just a configuration 
>> problem:
>>
>> I have a class Person which has one LONGVARCHAR-Field. The first time 
>> the object is accessed the LONGVARCHAR-field is returned correctly.
> 
> 
> hmm, does this mean first time after creation? Which cache was used?
> Maybe first time after store it was found in cache, second time it was 
> read from DB. So I assume your "database" truncate the String on insert.
> Maybe I'm wrong ;-)
> 
> regards,
> Armin
> 
>> But the second time it is accessed it returns just 256 (I suppose) 
>> characters.
>>
>> I am using Access as 'database' but I don't think this is the problem.
>>
>> Do you have any ideas what I could try?
>> Tino
>>
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
>> For additional commands, e-mail: ojb-user-help@db.apache.org
>>
>>
>>



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Re: Cache issue

Posted by Armin Waibel <ar...@apache.org>.
Hi,

Tino Schöllhorn wrote:

> Hi,
> 
> I have (again) something weird which I suppose is just a configuration 
> problem:
> 
> I have a class Person which has one LONGVARCHAR-Field. The first time 
> the object is accessed the LONGVARCHAR-field is returned correctly.

hmm, does this mean first time after creation? Which cache was used?
Maybe first time after store it was found in cache, second time it was 
read from DB. So I assume your "database" truncate the String on insert.
Maybe I'm wrong ;-)

regards,
Armin

> But 
> the second time it is accessed it returns just 256 (I suppose) characters.
> 
> I am using Access as 'database' but I don't think this is the problem.
> 
> Do you have any ideas what I could try?
> Tino
> 
> 
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
> 
> 
> 

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