Class IndexStatisticsDaemonImpl.KeyComparator

java.lang.Object
org.apache.derby.impl.services.daemon.IndexStatisticsDaemonImpl.KeyComparator
Enclosing class:
IndexStatisticsDaemonImpl

private static class IndexStatisticsDaemonImpl.KeyComparator extends Object
Support class used to compare keys when scanning indexes.
  • Field Details

  • Constructor Details

    • KeyComparator

      public KeyComparator(ExecIndexRow ir)
      Creates a key comparator for the given index.
      Parameters:
      ir - index row (template)
  • Method Details

    • fetchRows

      public int fetchRows(GroupFetchScanController gsc) throws StandardException
      Fetches rows from the scan controller.
      Parameters:
      gsc - the scan controller
      Returns:
      Number of rows fetched.
      Throws:
      StandardException - if fetching rows fails
    • compareWithPrevKey

      public int compareWithPrevKey(int index) throws StandardException
      Compares the key at the specified index with the previous key.
      Parameters:
      index - row index
      Returns:
      -1 if the current and previous key are identical, the index of the changed part of the key otherwise ([0, key length>)
      Throws:
      StandardException - if comparing the two keys fails
    • getRowCount

      public long getRowCount()
      Returns the number of rows fetched.
      Returns:
      Number of rows fetched.