how to use transaction isolation

["Gong" <fredkung@xxxxxxxx>]

In the java code below, I set the transaction isolation to serialization.

 

public class IsolationTest {

    private static String select = "select * from tmp where url = ''";

    public static void main(String[] args) throws Exception{

        //ConncetionFactory is a factory class for managing connection
        Connection con = ConnectionFactory.getConnection();  

        con.setTransactionIsolation(Connection.TRANSACTION_SERIALIZABLE);
        con.setAutoCommit(false);

        Statement smt = con.createStatement();
        ResultSet r1 = smt.executeQuery(select);
        System.out.println(r1.next());  //(1)   
        con.commit();               //(2)

        ResultSet r2 = smt.executeQuery(select);
        System.out.println(r2.next());  //(3)
        con.commit();
        smt.close();        

        ConnectionFactory.closeConnection();
    }
}

 

I set a break point at (2), then I run this code in debug mode. When it suspended at (2), line(1) print "false". Then, I execute an insert statement in pgadmin: insert into tmp values('aaa'), after that I continued to run the code, and line(3) print "true". I have set the transaction isolation to serialization, didn't the two select statements print the same result?

 

btw: postgresql version is 8.2, jdbc version is postgresql-8.2-506.jdbc3.jar, and jdk version is 1.5