[Hibernate-JIRA] Created: (HHH-4550) query cache: Attention with configuring Update Timestamps Cache region: expired entries cause wrong result sets!
by Guenther Demetz (JIRA)
query cache: Attention with configuring Update Timestamps Cache region: expired entries cause wrong result sets!
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Key: HHH-4550
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4550
Project: Hibernate Core
Issue Type: Improvement
Components: caching (L2)
Affects Versions: 3.3.2
Environment: 3.3.2 GA
Reporter: Guenther Demetz
Priority: Trivial
Attachments: TestCaseQuryCache.jar
When using hibernate's query cache (hibernate.cache.use_query_cache),
then it's of fundamental importance to configure the Update Timestamps cache region in
a way that his entries survive longer than the cached result sets in the Query cache region.
Otherwise queries could return wrong (obsolete) result sets (See attached testcase).
This is because the current UpdateTimestampsCache#isUpToDate implementation considers a result-set also as up-to-date,
if there are no update-timestamps cached for the interested spaces (tables) at all.
It if therefore important to notice that:
1- The Update-Timestamps-Cache-Region elements max-size should be configured higher than the number of tables you have
on the db-schema, in manner that he can remember/hold the last update-timestamp for each table.
2- If you use any other eviction policy in the Update-Timestamps-Cache-Region, then you must assure
that cached result sets in the Query-cache-region are evicted before relevant update-timestamps are going to be evicted.
This fact should be clearly documented somewhere.
Thanks
G.D.
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14 years, 2 months
[Hibernate-JIRA] Created: (HHH-3892) Improve support for mapping SQL LONGVARCHAR and CLOB to Java String, SQL LONGVARBINARY and BLOB to Java byte[]
by Gail Badner (JIRA)
Improve support for mapping SQL LONGVARCHAR and CLOB to Java String, SQL LONGVARBINARY and BLOB to Java byte[]
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Key: HHH-3892
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3892
Project: Hibernate Core
Issue Type: Improvement
Components: core
Reporter: Gail Badner
Assignee: Gail Badner
Fix For: 3.2.x, 3.3.x, 3.5
Property types will be provided to enable an application to process data for a java.sql.Types.LONGVARCHAR or java.sql.Types.CLOB column as a Java String. Hibernate will internally process the data as a streams. On a read, stream data will immediately be materialized into a Java string.
text - property type to map java.sql.Types.LONGVARCHAR column data as a Java String (via org.hibernate.type.TextType);
(NOTE: currently, org.hibernate.type.TextType incorrectly maps "text" to java.sql.Types.CLOB; this will be fixed by this issue and updated in database dialects)
materialized_clob - property type to map java.sql.Types.CLOB column data as a Java String (via org.hibernate.type.MaterializedClobType);
In addition, new property types will be provided to enable an application to process data for a java.sql.Types.LONGVARBINARY or java.sql.Types.BLOB column as Java byte[]. Hibernate will internally process the data as a streams. On a read, stream data will immediately be materialized into a Java byte[].
image - property type to map java.sql.Types.LONGVARBINARY column data as byte[] (via org.hibernate.type.ImageType);
materialized_blob - property type to map java.sql.Types.BLOB column data as byte[] (via org.hibernate.type.MaterializedBlobType);
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14 years, 2 months
[Hibernate-JIRA] Created: (HHH-4555) Support use of Envers with Auto-commit mode.
by Kevin Schmidt (JIRA)
Support use of Envers with Auto-commit mode.
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Key: HHH-4555
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4555
Project: Hibernate Core
Issue Type: New Feature
Components: envers
Affects Versions: 3.5.0-Beta-2
Environment: Hibernate 3.5.0-Beta-2
Reporter: Kevin Schmidt
Currently Envers is designed so that it synchronizes with the currently running transaction in order to know when to commit the inserts into the Audit Tables. This is an effective strategy for ensuring that the audit information is only saved to the database if the Transactional Unit of Work which caused the audit data to be created is committed.
This design creates a limitation on Envers such that it cannot persist audit information unless there is an active transaction. This effectively disables auditing for anyone modifying data using Hibernate outside of a Hibernate Transaction. Specifically, if you are using Autocommit = True and manually flushing the Hibernate Session then you cannot have any of your data audited using Envers.
I am not that well versed with the design of Envers but was hoping this situation could be detected and avoided. Maybe the audit information could be synchronized on the flush event rather than when a transaction is committed to the database.
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14 years, 2 months
[Hibernate-JIRA] Created: (HHH-3383) QueryKey is storing references to entities instead of identifiers
by Manuel Dominguez Sarmiento (JIRA)
QueryKey is storing references to entities instead of identifiers
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Key: HHH-3383
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3383
Project: Hibernate3
Issue Type: Improvement
Components: caching (L2)
Affects Versions: 3.3.0.CR1
Environment: ehcache 1.5.0b2
Reporter: Manuel Dominguez Sarmiento
Context: query caching
Hibernate is storing full entity references when building QueryKeys and the query has restrictions which reference entities. This happens either with Criteria or HQL queries.
Although this is not incorrect, when the referenced entities reference in turn "heavy" object graphs, this causes a very significant memory usage increase, since references to detached entities will remain in the cache. This is even more evident when using disk persistence with ehcache, since the full object graphs are serialized to disk.
This could be easily improved (correct me if I'm wrong) by storing ONLY entity identifiers in the QueryKey instead of full entities, since all the query really needs is the identifier property. The memory usage would decrease dramatically.
So far the workaround we've found is explicitly using restrictions that reference identifiers instead of properties in HQL queries, however this is not particularly elegant, and still leaves open the issue with Criteria queries. The same cannot be done without criteria.createCriteria() which generates an unnecessary join in most cases.
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14 years, 2 months