net.sf.farrago.query
Class FarragoRelMetadataQuery

java.lang.Object
  org.eigenbase.rel.metadata.RelMetadataQuery
      net.sf.farrago.query.FarragoRelMetadataQuery

public abstract class FarragoRelMetadataQuery
extends RelMetadataQuery

FarragoRelMetadataQuery defines the relational expression metadata queries specific to Farrago.

Version:

$Id: //open/dev/farrago/src/net/sf/farrago/query/FarragoRelMetadataQuery.java#5 $

Author:

John Sichi

Constructor Summary

FarragoRelMetadataQuery()

Method Summary

static boolean

canRestart(RelNode rel) Determines whether a physical expression can be restarted.

Methods inherited from class org.eigenbase.rel.metadata.RelMetadataQuery

areColumnsUnique, areColumnsUnique, getColumnOrigins, getCumulativeCost, getDistinctRowCount, getNonCumulativeCost, getPercentageOriginalRows, getPopulationSize, getRowCount, getSelectivity, getStatistics, getUniqueKeys, getUniqueKeys, isVisibleInExplain

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FarragoRelMetadataQuery

public FarragoRelMetadataQuery()

Method Detail

canRestart

public static boolean canRestart(RelNode rel)

Determines whether a physical expression can be restarted. For leaves, default implementation is true; for non-leaves, default implementation is conjunction of children.

Parameters:

rel - the relational expression

Returns:

true if restart is possible