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

    Modifier and Type
    Method
    Description
    long
    Returns the estimated number of rows in the index.
    double
    selectivity(Object[] predicates)
     
  • Method Details

    • getRowEstimate

      long getRowEstimate()
      Returns the estimated number of rows in the index.
      Returns:
      Number of rows.
    • selectivity

      double selectivity(Object[] predicates)
      Returns:
      the selectivity for a set of predicates.