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SQL Anywhere 12.0.0 (Français) » SQL Anywhere Server - SQL Usage » Query optimization and execution » How the optimizer works

 

Cost-based optimization with MIN and MAX functions

The min/max cost-based optimization is designed to exploit an existing index to compute efficiently the result of a simple aggregation query involving the MAX or MIN aggregate functions. The goal of this optimization is to be able to compute the result by retrieving only a few rows from the index. To be a candidate for this optimization, the query:

  • must not contain a GROUP BY clause

  • must be over a single table

  • must contain only a single aggregate function (MAX or MIN) in the query's SELECT-list

 Example