Spring3 /休眠声明失败

Question

Here is a simple hibernate code that inserts a value into a table. If the row already exists, query the row and return the data. Most of the time, the code works fine with no issues.

In a very special case, three different clients are trying to insert the exact the same row into the table. Ofcourse, only one row gets inserted. The other two insertions fail and the fall into the try-catch block.

There is a query in the try catch block, which queries the data and sends the value to the client. This results in an error for subsequent operations on the session.

Hibernate throws "ERROR org.hibernate.AssertionFailure - an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session)" in the logs.

Here is the code. What would be the right way to handle this scenario?

@Override
public void addPackage(PackageEntity pkg) {

    try{

        getCurrentSession().save(pkg);
        getCurrentSession().flush();

    }catch( ConstraintViolationException cve ){

        // UNIQ constraint is violated
        // query now, instead of insert
        System.out.println("Querying again because of UNIQ constraint : "+ pkg);
        PackageEntity p1 = getPackage(pkg.getName(), pkg.getVersion());

        if( p1 == null ){
            // something seriously wrong
            throw new RuntimeException("Unable to query or insert " + pkg);
        }else{
            pkg.setId(p1.getId());
        }

    }catch (Exception e) {
        e.printStackTrace();
    }catch (Throwable t) {
        t.printStackTrace();
    }
}

Answer 1

Primary (or) composite Key makes each row data unique and avoids this error.

If you need the data from all these three requests then create a unique primary key in your table and add it to the entity.

Primary Key could be any unique thing from your data, an auto generated sequence or UUID/GUID.