Conference orarep::nomahs::rdb_60

4959.0. "How to force ZIGZAG strategy using outlines??" by M5::DDAYBERR () Fri Jan 24 1997 11:32

    A question about how to force a zig-zag strategy using a query
    outline.   The inner loop table has an index,  lastname,firstname,
    and lastname is being used in the where clause.  From looking at 
    the documentation, it doesn't look like we can force the type
    of MATCH strategy, only that we can specify MATCH, , CROSS or ANY
    METHOD.  
    
    **   Is there a way, using query outlines, to force a ZIG-ZAG 
    strategy??   Here's the query outline created by RDB; following
    is a portion of the initial debug flags created by RDB when using
    the outline below.   BTY, this query outline is produced from a 
    view SELECT, and several other tables are used.  I've only put
    a partial example in here, because the question is specific to
    the inner strategy of the BI_CONSUMER table.
    
    
                                              Debbie
    
                                            
    create outline QO_00526328D2360671_00000000
    id '00526328D23606719014677CB7C3C40C'
    mode 0
    as (
      query (
        subquery (
          subquery (
            subquery (
              BI_PERSONAL 0   access path index       BI_PERSONAL_IDX1
                join by match to
              BI_CONSUMER 1   access path index       BI_CONSUMER_IDX2
    
    
    ~S: Outline BI_PER_CONS_OUTLINE used
    Solutions tried 106
    Solutions blocks created 72
    Created solutions pruned 0
    Cost of the chosen solution      4.3379867E+04
    Cardinality of chosen solution   8.4281508E-03
    ~S#0001
    Cross block of 18 entries
      Cross block entry 1
        Conjunct
        Match
          Outer loop
            Sort    Conjunct        Get
            Retrieval by index of relation BI_PERSONAL
              Index name  BI_PERSONAL_IDX1 [1:1] Bool
          Inner loop
            Temporary relation      Sort    Get
            Retrieval by index of relation BI_CONSUMER
              Index name  BI_CONSUMER_IDX2 [0:0]

        Sorry - the version is  RDB 6.1-04
    
    
                                  Debbie
    
    ps. not that I'm sorry the version is 6.1-04, but that I was sorry
    I forgot to mention it in my previous note.   ;-))

If a zig-zag is possible it will be used.  You can't force it to be used if
the query doesn't present that possibility.

Ian

         Thanks Ian!!
    
    
                  Debbie