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forum_thread

JPA query of a Set of terms

Hi, Is it possible to write a JPA query to select objects that contain a collection of elements? For example, suppose I have a table that maps a search terms to pages: @Entity public class SearchIndex { @Index SearchTerm term; @Index Page page; } Now suppose I have an array of SearchTerm objects. ie. ... ( "terms" , terms ) ; but it is not standard JPQL and it would be less efficient since indexes cannot be used. ...

 
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How to delete M2M relationship?

In user model class I have the following: public class User implements Serializable { ... a set of time slots in one invocation (as in your code) is not supported by JPA. If Timeslot is the owner of the many-to-many ...

 
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Object DB In memory : without Filestore

Hello, I raised this question earlier as well, we want to explore if I can run the ObjectDB completely in Memory ? (without any writes to Disk, it's okay to loose the data if the node is down ). I think that will give the best performance. The reason we are exploring is restoring state is possible for us through replaying the logs, however we want easier data structures which is really good with ObjectDB along with Concurrency controls and transaction mgmt. Let us know if it is possible to run the Object DB completely in memory without disk storage. ... As noted above, although ObjectDB does not support in memory mode, you can use a RAM drive. i.e. install a RAM drive ...

 
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How to create a Unique constraint?

Hi, I'm trying to create a unique constraint. Here is a simple example: @Entity public class Account { @Id @GeneratedValue private long id; @Index(unique="true") private String name; } The code runs and my Account objects are persisted. But no exception is thrown if name is the same. What do I need to do to have a Unique constraint? Thanks, Carl   ... ( "true" ) is widely used in JDO annotations but it is not very pretty. Update: Starting ObjectDB 2.6.6 new indexes are ...

 
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ObjectDB Manual

Hello,I would like to be able to read or refer to the ObjectDb manual (v2) on my Kindle. Unfortunately, I didn't find any option to download the manual, either as a .pdf (most convenient)or as a zipped set of .html files (a single file would be better for an easier conversion to .pdf) Is there such an option I'm unaware of on your website or could you make the manual available for offline reading?Very best regards,Paul... 19:08 The issue is not PDF generation for JDO but rewriting the new ObjectDB manual, converting ...

 
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How to define Default Entity Listeners without persistence.xml and orm.xml

I am using JPA programaticaly..ie without xml file, and i would like to define Default Entity Listeners. How to do ? Here my init code: ... You may also register listener using the JDO API, which is not documented but supported by ObjectDB. ObjectDB ...

 
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Which storage fits best to ObjectDB?

Hi, we are just about to put together a new server for our applications using ObjectDB (v 2.6). We have a dilemma about the storage holding the ObjectDB files: if to invest in a mirrored RAID of SSDs which is clearly the ultimate solution but it quite pricey, or to choose a RAID5/6 of 7200 RPM HDDs. ... data more often, so the seek-time is the most crucial and not the transfer-rate) ? edit ...

 
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First query takes 4+ minutes to complete

Hi, we are evaluating ObjectDB 2.5.1_04 in embedded mode hoping to replace SQLite in our application. We observed that in our case it takes on average more than 4 minutes to complete the first SELECT query that we run on the DB which contains about 320,000 records of a single type of object. SQLite in comparison responds within few seconds on average with the same number of records. We hope to receive your recommendation on how to improve this result with this post.   Test System ... In our case the fields are in the ORDER part. So, I do not think an index will help. Also, we tried a different query today: ... In our case the fields are in the ORDER part. So, I do not think an index will help. ObjectDB uses indexes also to sort ...

 
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Some technical questions

Hi, ObjectDB looks interesting. Have two technical questions... (1) what locking model does ObjectDB use? I.e. 2PL or MVCC? Do writers block readers? Do readers block writers? (2) what's the recommended usage for SAAS? One ObjectDB database per customer, or one ObjectDB database for all? Thank you, Andrej ... fetch this object without blocking? Yes, if it has not been locked with pessimistic WRITE. > , and will it see the old ...

 
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PersistenceException UserException: Failed to validate persistence.xml

I'm really tired of looking at the same exception all day. I have DaoService which gets initialized when app starts. ... But path acts right way. Finally I've got it. I should not use any persistence.xml at all. When I do not use it, I got this error: HTTP Status 500 - ...