Derby
  1. Derby
  2. DERBY-4251

Make Derby EmbedResultSet support getRow() for FORWARD_ONLY result sets

    Details

    • Type: Improvement Improvement
    • Status: Open
    • Priority: Major Major
    • Resolution: Unresolved
    • Affects Version/s: 10.4.2.0, 10.5.1.1
    • Fix Version/s: None
    • Component/s: JDBC
    • Environment:
      Windows XP, and Java 6 or Java 1.4.2
    • Urgency:
      Low
    • Bug behavior facts:
      Seen in production

      Description

      According to source of the Derby version I first found it in, and the version just released today, here is the offending code:

      https://svn.apache.org/repos/asf/db/derby/code/tags/10.5.1.1/java/engine/org/apache/derby/impl/jdbc/EmbedResultSet.java

      public int getRow() throws SQLException

      Unknown macro: { // getRow() is only allowed on scroll cursors checkScrollCursor("getRow()"); /* * * We probably needn't bother getting the text of * the underlying * statement but it is better to be * consistent and we aren't * particularly worried * about performance of getRow(). */ return theResults.getRowNumber(); }

      The comment and the check for scrollability is incorrect. The Javadoc comment for this getRow is a duplicate of the Sun JDK API for ResultSet.getRow(), and if the author had just written it according to their own javadoc there would be no problem.
      See spec here:
      http://java.sun.com/j2se/1.3/docs/api/java/sql/ResultSet.html#getRow()

      The Sun Javadoc does not spell out any exceptions to the required behaviour. getRow should always work regardless of whether the result set is scrollable because the issue of scrollability is whether the client can reposition the cursor to change the current row of the result set. Simply reading the current row number is different and unrelated to changing the current row number.
      Therefore getRow() should work for FORWARD_ONLY ResultSets, but Derby currently fails on this.

      Quite aside from the spec nonconformance, it's a bit annoying that my application has worked fine on Oracle, MS SQL, the JDBC-LDAP bridge driver, and even MS Access MDB files via the Sun JDBC-ODBC bridge driver, but then the Derby engine falls over just trying to run a simple Select statement on a non-updatable forward-only result set - the simplest kind of all!

      I haven't looked at what " theResults.getRowNumber() " does, but I hope the fix for this bug is as simple as removing the call to checkScrollCursor;

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          People

          • Assignee:
            Unassigned
            Reporter:
            Andrew McRae
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              Updated:

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