org.apache.derby.impl.sql.compile

Class Predicate

java.lang.Object

org.apache.derby.impl.sql.compile.QueryTreeNode

org.apache.derby.impl.sql.compile.Predicate

All Implemented Interfaces:

java.lang.Comparable<Predicate>, OptimizablePredicate, Visitable

public final class Predicate
extends QueryTreeNode
implements OptimizablePredicate, java.lang.Comparable<Predicate>

A Predicate represents a top level predicate.

Method Summary

Modifier and Type	Method and Description
int	compareTo(Predicate other)
boolean	compareWithKnownConstant(Optimizable optTable, boolean considerParameters) Is this predicate a comparison with a known constant value?
boolean	equalsComparisonWithConstantExpression(Optimizable optTable) Is this predicate an equality comparison with a constant expression? (IS NULL is considered to be an = comparison with a constant expression).
DataValueDescriptor	getCompareValue(Optimizable optTable) Get an Object representing the known constant value that the given Optimizable is being compared to.
int	getIndexPosition() Get the position of the index column that this predicate restricts.
JBitSet	getReferencedMap() Get the map of referenced tables for this OptimizablePredicate.
int	hasEqualOnColumnList(int[] baseColumnPositions, Optimizable optTable) Returns if the predicate involves an equal operator on one of the columns specified in the baseColumnPositions.
boolean	hasMethodCall() Return whether or not an OptimizablePredicate contains a method call.
boolean	hasSubquery() Return whether or not an OptimizablePredicate contains a subquery.
boolean	isQualifier() Is this predicate a qualifier?
boolean	isStartKey() Is this predicate a start key?
boolean	isStopKey() Is this predicate a stop key?
void	markQualifier() Tell the predicate that it is to be used as a qualifier in an index scan.
void	markStartKey() Tell the predicate that it is to be used as a column in the start key value for an index scan.
void	markStopKey() Tell the predicate that it is to be used as a column in the stop key value for an index scan.
double	selectivity(Optimizable optTable) Get a (crude) estimate of the selectivity of this predicate.
java.lang.String	toString() Convert this object to a String.

Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode

accept, addTag, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, bindUserType, checkReliability, checkReliability, createTypeDependency, getBeginOffset, getDataDictionary, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getOffsetOrderedNodes, getOptimizerFactory, getOptimizerTracer, getParameterTypes, getUDTDesc, isAtomic, makeConstantAction, makeTableName, makeTableName, optimizerTracingIsOn, orReliability, referencesSessionSchema, setBeginOffset, setEndOffset, taggedWith, treePrint

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

getReferencedMap

public JBitSet getReferencedMap()

Description copied from interface: OptimizablePredicate

Get the map of referenced tables for this OptimizablePredicate.

Specified by:

getReferencedMap in interface OptimizablePredicate

Returns:

JBitSet Referenced table map.

See Also:

OptimizablePredicate.getReferencedMap()

hasSubquery

public boolean hasSubquery()

Description copied from interface: OptimizablePredicate

Return whether or not an OptimizablePredicate contains a subquery.

Specified by:

hasSubquery in interface OptimizablePredicate

Returns:

boolean Whether or not an OptimizablePredicate includes a subquery.

See Also:

OptimizablePredicate.hasSubquery()

hasMethodCall

public boolean hasMethodCall()

Description copied from interface: OptimizablePredicate

Return whether or not an OptimizablePredicate contains a method call.

Specified by:

hasMethodCall in interface OptimizablePredicate

Returns:

boolean Whether or not an OptimizablePredicate includes a method call.

See Also:

OptimizablePredicate.hasMethodCall()

markStartKey

public void markStartKey()

Description copied from interface: OptimizablePredicate

Tell the predicate that it is to be used as a column in the start key value for an index scan.

Specified by:

markStartKey in interface OptimizablePredicate

See Also:

OptimizablePredicate.markStartKey()

isStartKey

public boolean isStartKey()

Description copied from interface: OptimizablePredicate

Is this predicate a start key?

Specified by:

isStartKey in interface OptimizablePredicate

See Also:

OptimizablePredicate.isStartKey()

markStopKey

public void markStopKey()

Description copied from interface: OptimizablePredicate

Tell the predicate that it is to be used as a column in the stop key value for an index scan.

Specified by:

markStopKey in interface OptimizablePredicate

See Also:

OptimizablePredicate.markStopKey()

isStopKey

public boolean isStopKey()

Description copied from interface: OptimizablePredicate

Is this predicate a stop key?

Specified by:

isStopKey in interface OptimizablePredicate

See Also:

OptimizablePredicate.isStopKey()

markQualifier

public void markQualifier()

Description copied from interface: OptimizablePredicate

Tell the predicate that it is to be used as a qualifier in an index scan.

Specified by:

markQualifier in interface OptimizablePredicate

See Also:

OptimizablePredicate.markQualifier()

isQualifier

public boolean isQualifier()

Description copied from interface: OptimizablePredicate

Is this predicate a qualifier?

Specified by:

isQualifier in interface OptimizablePredicate

See Also:

OptimizablePredicate.isQualifier()

compareWithKnownConstant

public boolean compareWithKnownConstant(Optimizable optTable,
                                        boolean considerParameters)

Description copied from interface: OptimizablePredicate

Is this predicate a comparison with a known constant value?

Specified by:

compareWithKnownConstant in interface OptimizablePredicate

Parameters:

optTable - The Optimizable that we want to know whether we are comparing to a known constant.

considerParameters - Whether or not to consider parameters with defaults as known constants.

See Also:

OptimizablePredicate.compareWithKnownConstant(org.apache.derby.iapi.sql.compile.Optimizable, boolean)

hasEqualOnColumnList

public int hasEqualOnColumnList(int[] baseColumnPositions,
                                Optimizable optTable)
                         throws StandardException

Description copied from interface: OptimizablePredicate

Returns if the predicate involves an equal operator on one of the columns specified in the baseColumnPositions.

Specified by:

hasEqualOnColumnList in interface OptimizablePredicate

Parameters:

baseColumnPositions - the column numbers on which the user wants to check if the equality condition exists.

optTable - the table for which baseColumnPositions are given.

Returns:

returns the index into baseColumnPositions of the column that has the equality operator.

Throws:

StandardException

getCompareValue

public DataValueDescriptor getCompareValue(Optimizable optTable)
                                    throws StandardException

Description copied from interface: OptimizablePredicate

Get an Object representing the known constant value that the given Optimizable is being compared to.

Specified by:

getCompareValue in interface OptimizablePredicate

Throws:

StandardException - Thrown on error

See Also:

OptimizablePredicate.getCompareValue(org.apache.derby.iapi.sql.compile.Optimizable)

equalsComparisonWithConstantExpression

public boolean equalsComparisonWithConstantExpression(Optimizable optTable)

Description copied from interface: OptimizablePredicate

Is this predicate an equality comparison with a constant expression? (IS NULL is considered to be an = comparison with a constant expression).

Specified by:

equalsComparisonWithConstantExpression in interface OptimizablePredicate

Parameters:

optTable - The Optimizable for which we want to know whether it is being equality-compared to a constant expression.

See Also:

OptimizablePredicate.equalsComparisonWithConstantExpression(org.apache.derby.iapi.sql.compile.Optimizable)

selectivity

public double selectivity(Optimizable optTable)
                   throws StandardException

Description copied from interface: OptimizablePredicate

Get a (crude) estimate of the selectivity of this predicate. This is to be used when no better technique is available for estimating the selectivity - this method's estimate is a hard- wired number based on the type of predicate and the datatype (the selectivity of boolean is always 50%).

Specified by:

selectivity in interface OptimizablePredicate

Parameters:

optTable - The Optimizable that this predicate restricts

Throws:

StandardException

See Also:

OptimizablePredicate.selectivity(org.apache.derby.iapi.sql.compile.Optimizable)

getIndexPosition

public int getIndexPosition()

Description copied from interface: OptimizablePredicate

Get the position of the index column that this predicate restricts. NOTE: This assumes that this predicate is part of an OptimizablePredicateList, and that classify() has been called on the OptimizablePredicateList.

Specified by:

getIndexPosition in interface OptimizablePredicate

Returns:

The index position that this predicate restricts (zero-based)

See Also:

OptimizablePredicate.getIndexPosition()

compareTo

public int compareTo(Predicate other)

Specified by:

compareTo in interface java.lang.Comparable<Predicate>

toString

public java.lang.String toString()

Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.

Overrides:

toString in class QueryTreeNode

Returns:

This object as a String