index is there but Oracle doesn't pick up the index
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Thread: index is there but Oracle doesn't pick up the index

  1. #1
    Join Date
    Jan 2005
    Posts
    221

    index is there but Oracle doesn't pick up the index

    I have index on level and for some reason it doesn't get pick up, I am trying to use the hint, can you help me to get the hint in so it can't pick up the index:

    Code:
      select  SHAPE,   SHAPE.fid,SHAPE.numofpts,SHAPE.entity,SHAPE.points,SHAPE.rowid from  beam.shapefile , beam.F75 SHAPE where (( level = 5 )) and SHAPE.FID(+) = beam.shapefile.SHAPE
      ------------------------------------------------------------
        
      Statement Id=0   Type=SELECT STATEMENT
      Cost=8715  TimeStamp=19-04-05::13::55:13
      
           (1)  SELECT STATEMENT  CHOOSE 
         Est. Rows: 244,014  Cost: 8,715
           (4)  HASH JOIN OUTER 
         Est. Rows: 244,014  Cost: 8,715
               (2)  TABLE ACCESS FULL beam.shapefile  [Analyzed] 
               (2)   Blocks: 36,439 Est. Rows: 244,014 of 976,054  Cost: 3,506 
                    Tablespace: DATA_TS_01
               (3)  TABLE ACCESS FULL beam.F75  [Analyzed] 
               (3)   Blocks: 19,234 Est. Rows: 976,054 of 976,054  Cost: 1,851 
                    Tablespace: DATA_TS_01

  2. #2
    Join Date
    Nov 2002
    Location
    Geneva Switzerland
    Posts
    3,142
    a) Are the "Est. Rows" about right?
    and
    b) How selective will "level=5" be?
    (I'm assuming level is in the table beam.shapefile.)

    If the answer to (a) is "yes", then the answer to (b) is "not very". So the full table scan will be the best option.
    "The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous" - Gibbon, quoted by R.P.Feynman

  3. #3
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    Jeff Hunter
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