5:25 p.m.
[
http://opensource.atlassian.com/projects/hibernate/browse/HHH-3339?page=c...
]
Chris Pheby commented on HHH-3339:
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I have encountered this issue also. The reason this occurs is that the timestamp attached
to the cache entry is 'session.getTimestamp()'. This means the issue will occur
whenever the same query is repeated within the same session.
In Hibernate 3.2.6 the fix is simply to change the line:
Long ts = new Long ( session.getTimestamp() );
to
Long ts = new Long (queryCache.nextTimestamp() );
You can work around this by subclassing StandardQueryCache and providing a
QueryCacheFactory implementation that overrides the put method with the above change. You
set the Hibernate property 'hibernate.cache.query_cache_factory' to be the name of
your custom factory. Note that the documentation at
http://www.hibernate.org/hib_docs/reference/en/html/session-configuration... is not
quite right, as it describes the property as being the 'The classname of a custom
QueryCache interface, defaults to the built-in StandardQueryCache. eg.
classname.of.QueryCache', when it is actually the name of the factory for the query
cache.
In the Hibernate code in trunk, the above change does not work due to refactoring of the
cache interfaces. I am attaching a patch which should be similar in effect.
Query cache stops working after object save
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Key: HHH-3339
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3339
Project: Hibernate3
Issue Type: Bug
Components: caching (L2)
Affects Versions: 3.2.6
Environment: Hibernate 3.2.6, MS SQL 2005 Database. Windows XP SP2
Reporter: Alex Oleynikov
Attachments: query_cache_bug.zip
It seems like HB Query cache stops working as soon as given object type is being saved
(it does not matter if it was save to existing object or insert of new object instance).
The code looks like this. Where User is just a primitive POJO with couple of properties.
// #1
query = session.createQuery("from User where userID = :id");
query.setCacheable(true);
query.setParameter("id", 10);
user = (User) query.list().get(0);
// #2
query = session.createQuery("from User where userID = :id");
query.setCacheable(true);
query.setParameter("id", 10);
user = (User) query.list().get(0);
// insert new User object
user = new User();
user.setUserID((int)(Math.random() * Integer.MAX_VALUE));
user.setUserName("Ten");
session.beginTransaction();
session.save(user);
session.getTransaction().commit();
// #3
query = session.createQuery("from User where userID = :id");
query.setCacheable(true);
query.setParameter("id", 10);
user = (User) query.list().get(0);
// #4
query = session.createQuery("from User where userID = :id");
query.setCacheable(true);
query.setParameter("id", 10);
user = (User) query.list().get(0);
From MS SQL Profiler I can clearly see that no queries is executed for #2 (e.g. it hit
the cache), but queries are executed for #3 and #4. From HB debug log I see following:
For #2 Query (cache is hit) - correct:
06:54:25,337 DEBUG StandardQueryCache:102 - checking cached query results in region:
org.hibernate.cache.StandardQueryCache
06:54:25,337 DEBUG StandardQueryCache:156 - Checking query spaces for up-to-dateness:
[USERS]
06:54:25,337 DEBUG StandardQueryCache:117 - returning cached query results
During User insert:
06:54:25,368 DEBUG UpdateTimestampsCache:65 - Invalidating space [USERS], timestamp:
4967466866147328
For #3 Query:
06:54:25,368 DEBUG StandardQueryCache:156 - Checking query spaces for up-to-dateness:
[USERS]
06:54:25,368 DEBUG UpdateTimestampsCache:86 - [USERS] last update timestamp:
4967466866147328, result set timestamp: 4967466865061888
06:54:25,368 DEBUG StandardQueryCache:113 - cached query results were not up to date
For #4 Query (or any subsequent query for this matter):
06:54:25,368 DEBUG StandardQueryCache:156 - Checking query spaces for up-to-dateness:
[USERS]
06:54:25,368 DEBUG UpdateTimestampsCache:86 - [USERS] last update timestamp:
4967466866147328, result set timestamp: 4967466865061888
06:54:25,368 DEBUG StandardQueryCache:113 - cached query results were not up to date
Please note the timestamp numbers for #4 query - even though I would expect query to be
re-cached in #3, it still shows old timestamp. So I may think that when re-caching a query
it does not update cache entry timestamp which is not up-to-date due to save().
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