About performance

forum_thread

Sorting problem

Hi, I was rewriting our DAO to support pagging in large dataset and I think I have found a problem with sorting. I send you a test case - sorry for using the same project as previous, but it was faster to write this test case. As usual, you can load data with DataLoader and then check problem with QueryData. There is a simple query with "order by" sentence: ... when the query is compiled. It is essential for better performance (same query can be used with different arguments without ...

 
forum_thread

Caching/Paging Questions...

Greetings ObjectDB team, All below questions assume a very large database (~1,000,000,000 objects): Q1: Two queries with a big overlap between their result sets. If I query the first set and hold the results in memory somehow, would that speed up the execution of the second query since many of its result objects already created and reside in memory ?... Using setFirstResult and setMaxResults could improve performance, but the effect is highly dependent on the specific query. ...

 
forum_thread

Possible issue with LAZY Loading

Hi, We need lazy loading for one of our large data sets. When I run currently against both 2.4.2 and 2.4.3_01 the db is always returning everything, including the data marked as Fetch.LAZY.  I wrote the attached unit test, and then found this: http://www.objectdb.com/database/forum/9 As far as I can tell, my unit test is pretty much identical. Not sure why this doesn't work. Thanks Paul. ... needed. You do see a difference (in addition to performance differences) when the EntityManager is closed or results are ...

 
forum_thread

Merge of entity classes with "mapped by" very slow

Hi, I have found a strange behavior when merging entities with "mapped by" set on @OneToMany relation. Even if object is fetched with find on the same transaction, merge is very slow. It's because on merge every single relation marked as LAZY is fetch from database. Attached two examples - one with mapped by, second with adding entities list without "mapped by". The difference is huge event for such small objects - 2ms (without mapped by) vs ~50ms (with mapped by) ... changed in build 2.4.3_01. Hopefully most of the performance gain will remain also with the new fix. ...

 
forum_thread

Safe Settings

Hi, I am trying to set up ObjectDb in a safe way that allows turning the machine off while database transactions are running. I would like to test if things are really safe and if I don't get corrupted database files in any possible case. I found "recovery" and "recording" in the objectdb.conf file. Which one is safer to use? I suppose I should turn on sync="true", right? ... of durability even when sync is disabled (and the performance would be better). There are many reasons why 100% durability ...

 
issue

Database access error , Doctor hanging on trying to repair, production shutdown at our biggest customer

we have a database shutdown, logs are showing: [2017-07-10 21:07:23 #1 store] Database 'F:\Hummingbird\Objectdb\db\coreSystemDb.odb' is opened by 11028@wzbhb101 [2017-07-10 21:07:23 #2 server] Server on port 3333 has started by 11028@wzbhb101 [2017-07-14 07:08:38 #3 store] SectionClassifier: SectionClassifier{2->merger[2699]-missing:1} [2017-07-14 07:09:08 #4 store] SectionClassifier: SectionClassifier{2->merger[2699]-missing:1} ... is permanently under heavy load. Recording affects the performance significantly, right ? ... is permanently under heavy load. Recording affects the performance significantly, right ? If you write the recording to a ...

 
issue

javax.servlet.ServletException: Annotated methods must follow the JavaBeans naming convention. __odbHidden_getPropertyName

NB: the following issue only happens with ObjectDB, it does not happen with EclipseLink.  Glassfish3.0.1 objectdb-2.2.5_10 JavaEE6 web app The error reports as: javax.servlet.ServletException: Annotated methods must follow the JavaBeans naming convention. __odbHidden_getWidthPxSideBarLeft Where getWidthPxSideBarLeft() is an annotated getter of an entity ViewConfiguration: Bug Version: 2.2.6 Priority: High Status: Fixed Replies: 9 Type:  Bug ...

 
forum_thread

Entity listener - event instead of object

Hi, Currently I'm playing with entity listener to implement auditing with difference between values in updated entity. There is a problem however with accessing "old" version of object stored in database. I can't find the nice way to use EntityManager in EntityListener. Because of that, I can't store separate entity for given event. Right now I'm using BaseEntity which contains #1 2011-07-20 12:49 Hi, Currently I'm playing with entity listener to implement auditing with difference between values i ...

 
forum_thread

Empty temporary dat files in the temp folder

Hello, We have questions regarding the pagesX.dat files in the temp directory. We detected a problem on a machine with ‘only’ 2GB free memory on disc drive C:/ because during using our Product the %temp%/objectdb_123... folder growth up to 2GB. And then we run into some following errors due to lack of memory. ... to reduce the initial size (actually 8MB)? - What performance advantages bring these files? Is this possible/ advisable to ...

 
forum_thread

Lazy Init / Eager / Join Fetch collection strategy ? What to choose ?

Hello, I'm doing some tests to choose the best collection fetch strategy. I have entities with many lazy collections and i don't want to load them all. In JPA / Hibernate world it exist some tests demonstrating how to choose the best strategy. For example : http://zeroturnaround.com/rebellabs/how-to-use-jpa-correctly-to-avoid-complaints-of-a-slow-application/ In this article,join fetch seems to be the right choice. What about ObjectDb ? The implementation is totally different. ... specific scenario to tune your application for maximum performance. ObjectDB Support ObjectDB - Fast ...