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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DERBY-6670) Rollback to savepoint allows violation of deferrable constraints
Date Thu, 17 Jul 2014 16:39:06 GMT
Knut Anders Hatlen created DERBY-6670:

             Summary: Rollback to savepoint allows violation of deferrable constraints
                 Key: DERBY-6670
                 URL: https://issues.apache.org/jira/browse/DERBY-6670
             Project: Derby
          Issue Type: Bug
          Components: SQL
    Affects Versions:
            Reporter: Knut Anders Hatlen

The bug is illustrated by the following code snippet:

        Connection c = DriverManager.getConnection("jdbc:derby:memory:db;create=true");
        Statement s = c.createStatement();
        s.execute("create table t1(x int primary key initially deferred)");
        s.execute("insert into t1 values 1,1,1,1");

        Savepoint sp = c.setSavepoint();
        s.execute("drop table t1");

        // Since there are four identical rows in T1, this call should have
        // failed because the primary key was violated.

        // Instead, it succeeds, and all four rows are committed, as can
        // be seen here:
        ResultSet rs = s.executeQuery("select * from t1");
        while (rs.next()) {

        // Insert yet another row, so that we have five identical rows ...
        s.execute("insert into t1 values 1");
        // ... and now commit complains ...

With auto-commit off, add duplicates into a deferred primary key. Then set a savepoint, drop
the table, and roll back to the savepoint.

Apparently, when you drop the table, information about any constraint violations seen on that
table is lost, and that information is not restored when the drop table operation is undone
by the rollback to savepoint.

So when you commit the transaction after having rolled back the drop operation, no deferred
checking of constraints happens, and the duplicates you have inserted are committed.

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