org.apache.derby.impl.sql.execute
Class GenericQualifier

java.lang.Object
  extended by org.apache.derby.impl.sql.execute.GenericQualifier
All Implemented Interfaces:
Qualifier

public class GenericQualifier
extends java.lang.Object
implements Qualifier

This is the implementation for Qualifier. It is used for generated scans.


Field Summary
private  Activation activation
           
private  int columnId
           
private  boolean negateCompareResult
           
private  int operator
           
private  DataValueDescriptor orderableCache
           
private  GeneratedMethod orderableGetter
           
private  boolean orderedNulls
           
private  boolean unknownRV
           
protected  int variantType
           
 
Fields inherited from interface org.apache.derby.iapi.store.access.Qualifier
CONSTANT, QUERY_INVARIANT, SCAN_INVARIANT, VARIANT
 
Constructor Summary
GenericQualifier(int columnId, int operator, GeneratedMethod orderableGetter, Activation activation, boolean orderedNulls, boolean unknownRV, boolean negateCompareResult, int variantType)
           
 
Method Summary
 void clearOrderableCache()
          Clear the DataValueDescriptor cache, if one exists.
 int getColumnId()
          Get the (zero based) 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()
          Should the result from the compare operation be negated?
 void reinitialize()
          This method reinitializes all the state of the Qualifier.
 java.lang.String toString()
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

columnId

private int columnId

operator

private int operator

orderableGetter

private GeneratedMethod orderableGetter

activation

private Activation activation

orderedNulls

private boolean orderedNulls

unknownRV

private boolean unknownRV

negateCompareResult

private boolean negateCompareResult

variantType

protected int variantType

orderableCache

private DataValueDescriptor orderableCache
Constructor Detail

GenericQualifier

public GenericQualifier(int columnId,
                        int operator,
                        GeneratedMethod orderableGetter,
                        Activation activation,
                        boolean orderedNulls,
                        boolean unknownRV,
                        boolean negateCompareResult,
                        int variantType)
Method Detail

getColumnId

public int getColumnId()
Description copied from interface: Qualifier
Get the (zero based) id of the column to be qualified.

This id is the column number of the column in the table, no matter whether a partial column set is being retrieved by the actual fetch. Note that the column being specified in the qualifier must appear in the column list being fetched.

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

getOrderable

public DataValueDescriptor getOrderable()
                                 throws StandardException
Description copied from interface: Qualifier
Get the value that the column is to be compared to.

Specified by:
getOrderable in interface Qualifier
Throws:
StandardException - Thrown on error
See Also:
Qualifier.getOrderable()

getOperator

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

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

negateCompareResult

public boolean negateCompareResult()
Should the result from the compare operation be negated? If true then only rows which fail the compare operation will qualify.

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

getOrderedNulls

public boolean getOrderedNulls()
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:
Qualifier.getUnknownRV()

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 - never changes

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

toString

public java.lang.String toString()
Overrides:
toString in class java.lang.Object

Built on Thu 2011-03-10 11:54:14+0000, from revision ???

Apache Derby V10.6 Internals - Copyright © 2004,2007 The Apache Software Foundation. All Rights Reserved.