Category Archives: JPA

Performance, benchmarking

Every so often some individual or group decides they’re going to “invent” a new benchmark. They ignore all that have been done before (like PolePos) maybe due to NotInventedHereSyndrome, or maybe due to “oh someone who helped write that was … Continue reading

Posted in JDO, JPA, Persistence | 3 Comments

DataNucleus v3 and MongoDB

There has obviously been a recent shift to look at highly scalable datastores for use in “the cloud”. Google wrote a plugin for their own BigTable datastore back in 2009, providing access to some of the features of JDO/JPA. Unfortunately … Continue reading

Posted in JDO, JPA, MongoDB, NoSQL | Leave a comment

JPA : TCK request and JPA2.1

It is now almost exactly a year since we submitted a request for access to the JPA2 TCK (JSR0317). We provided everything requested of us by Oracle, and we still haven’t received the JPA2 TCK. Just to say Happy Anniversary … Continue reading

Posted in JCP, JPA, Oracle | 1 Comment

DataNucleus v3 and HBase

DataNucleus AccessPlatform v3 provides an opportunity to bring some of our other datastore plugins closer to the standard of the more mature long-supported datastores (e.g RDBMS). In the case of HBase, the plugin provided with v2.0 offered basic persistence and … Continue reading

Posted in hbase, JDO, JPA, NoSQL | 3 Comments

JDO Typesafe .vs. JPA Criteria

JPA2 introduced its “Criteria” queries, providing an API for typesafe query generation without the need to hardcode field names etc in queries; it built on the approach of Hibernate Criteria. DataNucleus includes a proposal for JDO “Typesafe” queries. It takes … Continue reading

Posted in Criteria, JDO, JDOQL, JPA, LINQ, Typesafe | 9 Comments

JDO Typesafe Queries : Part 3 – Examples

In two previous blog posts, we introduced the idea of having a typesafe refactor friendly API for queries for JDO, and then described typical expression types necessary to achieve that. In this blog post we take that a step further, … Continue reading

Posted in JDO, JDOQL, JPA, LINQ, Typesafe | 15 Comments

Persisting multisets (bags) with DataNucleus

A multiset is a set where you can have a particular object multiple times in the set (a normal java.util Set will remove dups). This is also known by some as a “bag”. Google’s Collections library has such a container … Continue reading

Posted in JDO, JPA, Persistence | Leave a comment