Question

I am using Hibernate 3.0 in my application with Postgres database. It is a monitoring application and gathers data every minute. So we have thousands of rows in some tables every month.

Currently i am using sequence for generating Id in hibernate. Is there any better option according to this scenario?

Any suggestion will be appreciated.

Answer 1

IMHO sequence is the best approach because it gives you more flexibility although you may also use identity (auto-increment) column. I think it postgres it is called serial and there is also a way to store ids in sepearate table. To address these 3 approach you may use
appropriately :

@GeneratedValue(strategy=GenerationType.TABLE)
@GeneratedValue(strategy=GenerationType.SEQUENCE)
@GeneratedValue(strategy=GenerationType.IDENTITY)

As for your previous question whether it is good to use single sequence for all tables. I wouldn’t recommend this approach becasue db must assert that all sequence numbers are unique that is why each sequence generated value needs to be synchronized by the db server. If you have single sequence per db it may cause performace issues when multiple requests from multiple tables asks for next id value. I would rather recommend to have single sequence per table.