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From "Kathey Marsden (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DERBY-5473) Index growth can occur with update of ever increasing values i
Date Fri, 21 Oct 2011 19:38:32 GMT
Index growth can occur with update of ever increasing values i
--------------------------------------------------------------

                 Key: DERBY-5473
                 URL: https://issues.apache.org/jira/browse/DERBY-5473
             Project: Derby
          Issue Type: Bug
          Components: Store
            Reporter: Kathey Marsden


Attaching a reproduction for this issue ReproIdxGrowth.

The program has a single thread that iteratively updates 5 rows in a table with a time value.
 PreparedStatement ps = conn.prepareStatement(
        "UPDATE T SET LAST_SYNC_TIME = ?, NUM_SYNCS = ? WHERE ACCOUNT_ID = ?");

        ResultSet rs = s.executeQuery("SELECT ACCOUNT_ID, NUM_SYNCS FROM  T");
        while( rs.next()) {
            int account = rs.getInt(1);
            int prevNumSync = rs.getInt(1);
            ps.setLong(1, new Date().getTime());
            ps.setInt(2,prevNumSync++);
            ps.setInt(3, account);
            ps.executeUpdate();
        }

After 50,000 iterations we end up with 150 pages allocated for the just the 5 rows, possibly
because it cannot get the table lock to rebalance the tree.


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