1958952 - ASE: Statistics from huge tables show a large skew and majority of values are in the last histogram step | SAP Knowledge Base Article

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1958952 - ASE: Statistics from huge tables show a large skew and majority of values are in the last histogram step

Symptom

  • The last step in the histogram's Step Weight Value represents 64% of the data
     
  • Statistics  from huge tables shows a large skew for the last histogram step, even  after executing  'update statistics'
     
  • This is an example of the last 3 steps for a table that has more than 2.1 billion (2^31) rows using  1000 steps
       ...
       998 0.00000000 < "Feb 13 2009 12:00:00:000AM"
       999 0.00045268 = "Feb 13 2009 12:00:00:000AM"
       1000 0.64416260 < = "Jan 1 2099 12:00:00:000AM"
     
  •  When statistics are skewed like this the optimizer may not have the best query plan and  table scans might be used

Read more...

Environment

SAP ASE Adaptive Server Enterprise (ASE) 15.x

Product

SAP Adaptive Server Enterprise 15.7 ; Sybase Adaptive Server Enterprise 15.0 ; Sybase Adaptive Server Enterprise 15.5

Keywords

unbalanced weight , KBA , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Bug Filed

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