postgresql « MySQL « JPA Q&A

1. Sparse data: efficient storage and retrieval in an RDBMS

I have a table representing values of source file metrics across project revisions, like the following:

Revision FileA FileB FileC FileD FileE ...
1          ...

2. Hibernate database specific columnDefinition values

the problem is as follows: We're using hibernate with annotations as O/R Mapper. Some @Column annotations look like: @Column(columnDefinition = "longblob", name = "binaryData", nullable = true) or @Column(columnDefinition = "mediumtext", name = "remark", nullable ...

3. Hibernate One To Many Problem

I am doing a proof of concept for one to many mapping with no success. My schema is as follows:

Student ---->Phone
class Student
public class Student implements 
   private Set<Phone> ...