org.apache.derby.catalog.types
Class StatisticsImpl
java.lang.Object
org.apache.derby.catalog.types.StatisticsImpl
- All Implemented Interfaces:
- java.io.Externalizable, Formatable, java.io.Serializable, Statistics, TypedFormat
- public class StatisticsImpl
- extends java.lang.Object
- implements Statistics, Formatable
- See Also:
- Serialized Form
Constructor Summary |
StatisticsImpl()
Zero argument constructor for Formatable Interface |
StatisticsImpl(long numRows,
long numUnique)
Constructor for StatisticsImpl. |
Method Summary |
int |
getTypeFormatId()
Get a universally unique identifier for the type of
this object. |
void |
readExternal(java.io.ObjectInput in)
|
double |
selectivity(java.lang.Object[] predicates)
|
java.lang.String |
toString()
|
void |
writeExternal(java.io.ObjectOutput out)
Write this object to a stream of stored objects. |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
numRows
private long numRows
numUnique
private long numUnique
StatisticsImpl
public StatisticsImpl(long numRows,
long numUnique)
- Constructor for StatisticsImpl.
- Parameters:
numRows
- number of rows in the conglomerate for which
this statistic is being created.numUnique
- number of unique values in the key for which
this statistic is being created.
StatisticsImpl
public StatisticsImpl()
- Zero argument constructor for Formatable Interface
selectivity
public double selectivity(java.lang.Object[] predicates)
- Specified by:
selectivity
in interface Statistics
- Returns:
- the selectivity for a set of predicates.
- See Also:
Statistics.selectivity(java.lang.Object[])
readExternal
public void readExternal(java.io.ObjectInput in)
throws java.io.IOException,
java.lang.ClassNotFoundException
- Specified by:
readExternal
in interface java.io.Externalizable
- Throws:
java.io.IOException
java.lang.ClassNotFoundException
- See Also:
Externalizable.readExternal(java.io.ObjectInput)
writeExternal
public void writeExternal(java.io.ObjectOutput out)
throws java.io.IOException
- Write this object to a stream of stored objects.
- Specified by:
writeExternal
in interface java.io.Externalizable
- Parameters:
out
- write bytes here.
- Throws:
java.io.IOException
- thrown on error
getTypeFormatId
public int getTypeFormatId()
- Description copied from interface:
TypedFormat
- Get a universally unique identifier for the type of
this object.
- Specified by:
getTypeFormatId
in interface TypedFormat
- Returns:
- the format id which corresponds to this class.
toString
public java.lang.String toString()
- See Also:
Object.toString()
Apache Derby V10.1 Engine Documentation - Copyright © 1997,2005 The Apache Software Foundation or its licensors, as applicable.