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3003135 - Trace flags 364 and 16982 are available for tuning suboptimal query plan having skew data in join columns - SAP ASE

Symptom

  • A join query joining involving two or more tables is slow due to a suboptimal query plan. 
  • There exists another faster query plan using a different index or different join order.
  • There exists join column with skew data, a related column histogram in optdiag output shows ‘Total density’ is much higher than ‘Range cell density’, e.g.

    Statistics for column:                  "column_name"          
    Range cell density:             0.0001233381992404           
    Total density:                     0.3222680491657743


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Environment

  • SAP Adaptive Server Enterprise (ASE) 15.7
  • SAP Adaptive Server Enterprise (ASE) 16.0

Product

SAP Adaptive Server Enterprise all versions

Keywords

suboptimal query plan, CR 727887, 727887, Range cell density, Total density, trace flag 364, trace flag 16982

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, KBA , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Product Enhancement

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