org.apache.derby.impl.store.access
Class UTFQualifier

java.lang.Object
  extended byorg.apache.derby.impl.store.access.UTFQualifier
All Implemented Interfaces:
Qualifier

public class UTFQualifier
extends java.lang.Object
implements Qualifier


Field Summary
private  int columnId
           
private  UTF value
           
 
Fields inherited from interface org.apache.derby.iapi.store.access.Qualifier
CONSTANT, QUERY_INVARIANT, SCAN_INVARIANT, VARIANT
 
Constructor Summary
UTFQualifier(int columnId, java.lang.String value)
           
 
Method Summary
 void clearOrderableCache()
          Clear the DataValueDescriptor cache, if one exists.
 int getColumnId()
          Get the id of the column to be qualified.
 int getOperator()
          Get the operator to use in the comparison.
 DataValueDescriptor getOrderable()
          Get the value that the column is to be compared to.
 boolean getOrderedNulls()
          Get the getOrderedNulls argument to use in the comparison.
 boolean getUnknownRV()
          Get the getOrderedNulls argument to use in the comparison.
 boolean negateCompareResult()
          Determine if the result from the compare operation is to be negated.
 void reinitialize()
          This method reinitializes all the state of the Qualifier.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

value

private UTF value

columnId

private int columnId
Constructor Detail

UTFQualifier

public UTFQualifier(int columnId,
                    java.lang.String value)
Method Detail

getColumnId

public int getColumnId()
Get the id of the column to be qualified.

Specified by:
getColumnId in interface Qualifier

getOrderable

public DataValueDescriptor getOrderable()
Get the value that the column is to be compared to.

Specified by:
getOrderable in interface Qualifier
Throws:
StandardException - Thrown on error

getOperator

public int getOperator()
Get the operator to use in the comparison.

Specified by:
getOperator in interface Qualifier
See Also:
DataValueDescriptor.compare(org.apache.derby.iapi.types.DataValueDescriptor)

negateCompareResult

public boolean negateCompareResult()
Determine if the result from the compare operation is to be negated.

If true then only rows which fail the compare operation will qualify.

Specified by:
negateCompareResult in interface Qualifier
See Also:
DataValueDescriptor.compare(org.apache.derby.iapi.types.DataValueDescriptor)

getOrderedNulls

public boolean getOrderedNulls()
Description copied from interface: Qualifier
Get the getOrderedNulls argument to use in the comparison.

Specified by:
getOrderedNulls in interface Qualifier
See Also:
Qualifier.getOrderedNulls()

getUnknownRV

public boolean getUnknownRV()
Get the getOrderedNulls argument to use in the comparison.

Specified by:
getUnknownRV in interface Qualifier
See Also:
DataValueDescriptor.compare(org.apache.derby.iapi.types.DataValueDescriptor)

clearOrderableCache

public void clearOrderableCache()
Clear the DataValueDescriptor cache, if one exists. (The DataValueDescriptor can be 1 of 3 types: o VARIANT - cannot be cached as its value can vary within a scan o SCAN_INVARIANT - can be cached within a scan as its value will not change within a scan o QUERY_INVARIANT- can be cached across the life of the query as its value will never change o CONSTANT - can be cached across executions

Specified by:
clearOrderableCache in interface Qualifier
See Also:
Qualifier.getUnknownRV()

reinitialize

public void reinitialize()
This method reinitializes all the state of the Qualifier. It is used to distinguish between resetting something that is query invariant and something that is constant over every execution of a query. Basically, clearOrderableCache() will only clear out its cache if it is a VARIANT or SCAN_INVARIANT value. However, each time a query is executed, the QUERY_INVARIANT qualifiers need to be reset.

Specified by:
reinitialize in interface Qualifier

Built on Tue 2006-10-10 19:23:47+0200, from revision exported

Apache Derby V10.1 Engine Documentation - Copyright © 1997,2005 The Apache Software Foundation or its licensors, as applicable.