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 Cloudscape optimizer to estimate cost
and selectivity of different query plans.
Method Summary |
double |
selectivity(java.lang.Object[] predicates)
|
selectivity
public double selectivity(java.lang.Object[] predicates)
- Returns:
- the selectivity for a set of predicates.
Apache Derby V10.1 Engine Documentation - Copyright © 1997,2005 The Apache Software Foundation or its licensors, as applicable.