Adaptive Query Processing

Synonyms

Adaptive query optimization; Autonomic query processing; Eddies;

Definition

While in traditional query processing, a query is first optimized and then executed, adaptive query processing techniques use runtime feedback to modify query processing in a way that provides better response time, more efficient CPU utilization or more useful incremental results. Adaptive query processing makes query processing more robust to optimizer mistakes, unknown statistics, and dynamically changing data, runtime and workload characteristics. The spectrum of adaptive query processing techniques is quite broad: they may span the executions of multiple queries or adapt within the execution of a single query; they may affect the query plan being executed or just the scheduling of operations within the plan.

Key Points

Conventional query processing follows an optimize-then-execute strategy: after generating alternative query plans, the query optimizer selects the most cost-efficient among them and...