SAP Knowledge Base Article - Preview

2543976 - Unrelated index selection by optimizer

Symptom

  • Unrelated index selection by optimizer in query plan on test but not production.
  • The difference in showplan is that on test it chooses index1 that includes (colA, colD) where on prod it the index2 includes (colA, colC).
  • The column colA and colC are in the WHERE clause but colD is not.
  • The process on test takes 11 minutes 20 seconds but on prod it takes 3 minutes and 50 seconds.
  • Even when the same plan and indexes are forced on test the query with identical data takes longer.


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Environment

  • SAP Adaptive Server Enterprise (ASE)

Product

SAP Adaptive Server Enterprise 15.7

Keywords

"query performance", "physical I/O", "physical i/o", "Optimized using Serial Mode", "Optimized using Parallel Mode", "optimizer question", "wrong index" , KBA , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Problem

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