org.apache.derby.catalog
Interface Statistics
- All Known Implementing Classes:
- StatisticsImpl
public interface Statistics
This interface is used in the column SYS.SYSSTATISTICS.STATISTICS. It
encapsulates information collected by the UPDATE STATISTICS command
and is used internally by the Derby optimizer to estimate cost
and selectivity of different query plans.
Method Summary |
double |
selectivity(java.lang.Object[] predicates)
|
selectivity
double selectivity(java.lang.Object[] predicates)
- Returns:
- the selectivity for a set of predicates.
Apache Derby V10.6 Internals - Copyright © 2004,2007 The Apache Software Foundation. All Rights Reserved.