Hi all.
I need to implement a counter logic. Database should contain a table COUNTER which whill consits of such columns:
id: number
name: varchar
count: number

Also I have a class Counter.java which is mapped to previous table.
Each counter has its name and an index. Concurent thread try to get counter by name, if counter doesn't exist thread creates it otherwise - just increments counter's index.

I have read many books and articles about concurent programming with hibernate but I still has no ideas how to prevent concurent attempts of row creation.

I understend than the solvation is connected with usage of pesimistic locking, but hibernate doesn't allow to lock a table. It only allows to lock a row connected with existent instance.

An another approach I have considered is to use serializable isolation level of transaction. Accordingly to documentaion such level of transaction will not allow concurent creation of rows. But such approach is not effective. My test still fails with primary key constaint violation.

I have no other ideas. Please help me to understand what should be done to prevent concurent row creation.

Hi silj,

Use version column inDB and map it with

<version /> in HBM

or you could use timestamp

Hi. Thanks for the previoous reply. I cannot use nether version number nor timestamp because:
1) I'm using a legacy database. I have no possibilities to change it.
2) My application is not the only who uses this database. There are many other legacy applications which are usning it too.

Thanks

Hi silj,
then i don't think you are able to do that from Hibernate.Try to design Lock manager.Or you could ask from Hibernate Team.

I have created a temporary solution. I'm using such method at the begining of a transaction:

This works. I'm planning move this code to interceptor.
I hope that it's temporary solution and the best one should be found.