
7.2 How Oracle SQL Is Executed 189
Chapter 7
Influence the Optimizer
ALL_ROWS. Suppresses indexes and favors full table scans to find all
rows.
FIRST_ROWS(n). More likely to use indexing, because the query
plan should assume that only the first n rows for a query will be
retrieved.
CPU_COSTING. Default mode, persuades the optimizer to esti-
mate query execution time based on CPU cycles and I/O activity.
This hint fills a column in the PLAN_TABLE called CPU_COST,
based on CPU cycles and I/O operations.
NO_CPU_COSTING. Ignores CPU cycles, basing query execution
time estimation on I/O activity only.
CURSOR_SHARING_EXACT. Overrides behavior of configura- ...