The Sybase IQ query optimizer evaluates every query, choosing among various processing options to produce a query plan that offers optimal performance. The optimizer is tuned for each release of Sybase IQ to choose the best plan for most queries and most databases, including the largest ones.
For information on options that let you examine and influence the query plan, and suggestions for structuring queries for optimal performance, see Chapter 3, “Optimizing Queries and Deletions,” in Performance and Tuning Guide.