My Work at GSoC -2010

Derby Graphical Query Explainer

Apache Derby

Graphical Query Explainer

Query: SELECT a.USER_ID, a.USER_NAME, b.account_id FROM Users a JOIN Messaged_Users b ON a.USER_ID=b.USER_ID AND b.account_id=(?)



  • PROJECTION
    returned_rows1
    no_opens1

    • |_ HASHJOIN
      returned_rows1
      no_opens1

      • |_ TABLESCAN
        returned_rows100000
        no_opens1
        visited_pages2165
        scan_qualifiersNone
        scanned_objectUSERS
        scan_typeHEAP

        • |_ HASHSCAN
          returned_rows1
          no_opens100000
          visited_pages3
          scan_qualifiersNone
          next_qualifiersColumn[0][0] Id: 1 Operator: = Ordered nulls: false Unknown return value: false Negate comparison result: false
          scanned_objectPK_ACC_USER_ID
          scan_typeBTREE