Re: how to use transaction isolation

On 4/10/08, Gong <fredkung@sohu.com> wrote:
>
>
> In the java code below, I set the transaction isolation to serialization.
>
> public class IsolationTest {
>
>     private static String select = "select * from tmp where url = 'aaa'";
>
>     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?

Your commit at (2) ends the transaction, and the second select runs in
a new one.