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2255762 - A forced index cannot be used in a query - SAP ASE

Symptom

  • A forced index cannot be used in queries. 
  • From this query plan, we can see the forced index ncsysusers2 cannot be used in this query:

1> select name from sysusers(index ncsysusers2)  where name="dbo"
2> go

QUERY PLAN FOR STATEMENT 1 (at line 1).
Optimized using Serial Mode 

    STEP 1

        The type of query is SELECT.
        1 operator(s) under root 

       |ROOT:EMIT Operator (VA = 1)
       |
       |   |SCAN Operator (VA = 0)
       |   |  FROM TABLE
       |   |  sysusers
       |   |  Index : ncsysusers1
       |   |  Forward Scan.
       |   |  Positioning by key.
       |   |  Index contains all needed columns. Base table will not be read.
       |   |  Keys are:
       |   |    name ASC
       |   |  Using I/O Size 8 Kbytes for index leaf pages.
       |   |  With LRU Buffer Replacement Strategy for index leaf pages. 


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Environment

SAP 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

"trace flag", hint, optimizer, 15038, -T15038 , KBA , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Problem

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