org.eigenbase.stat
Interface RelStatSource

All Known Implementing Classes:

FarragoTableStatistics

public interface RelStatSource

This class encapsulates statistics for a RelNode

Version:

$Id: //open/dev/farrago/src/org/eigenbase/stat/RelStatSource.java#6 $

Author:

John Pham

Method Summary

RelStatColumnStatistics	getColumnStatistics(int ordinal, SargIntervalSequence predicate) Returns statistics pertaining to a column specified by the 0-based ordinal and the sargable predicates associated with that column.
Double	getRowCount() Returns the number of rows in a relation, as determined by statistics

Method Detail

getRowCount

Double getRowCount()

Returns the number of rows in a relation, as determined by statistics

Returns:

a row count, or null if one could not be determined

getColumnStatistics

RelStatColumnStatistics getColumnStatistics(int ordinal,
                                            SargIntervalSequence predicate)

Returns statistics pertaining to a column specified by the 0-based ordinal and the sargable predicates associated with that column. The second argument can be null if there are no sargable predicates on the column.

Parameters:

ordinal - zero based column ordinal

predicate - associated predicates(s), evaluated as intervals

Returns:

filtered column statistics, or null if they could not be obtained