org.apache.derby.impl.sql.compile

Class IsNullNode

java.lang.Object

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

org.apache.derby.impl.sql.compile.ValueNode

org.apache.derby.impl.sql.compile.OperatorNode

org.apache.derby.impl.sql.compile.UnaryOperatorNode

org.apache.derby.impl.sql.compile.UnaryComparisonOperatorNode

org.apache.derby.impl.sql.compile.IsNullNode

All Implemented Interfaces:

Node, Visitable, RelationalOperator

public final class IsNullNode
extends UnaryComparisonOperatorNode
implements RelationalOperator

This node represents either a unary IS NULL or IS NOT NULL comparison operator

Field Summary

Fields

Modifier and Type	Field and Description
private DataValueDescriptor	nullValue

Fields inherited from class org.apache.derby.impl.sql.compile.UnaryOperatorNode

methodName, operand, operator, receiverInterfaceType, resultInterfaceType, UnaryArgTypes, UnaryMethodNames, UnaryOperators, UnaryResultTypes, XMLPARSE_OP, XMLSERIALIZE_OP

Fields inherited from class org.apache.derby.impl.sql.compile.ValueNode

transformed

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

AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX

Fields inherited from interface org.apache.derby.impl.sql.compile.RelationalOperator

EQUALS_RELOP, GREATER_EQUALS_RELOP, GREATER_THAN_RELOP, IS_NOT_NULL_RELOP, IS_NULL_RELOP, LESS_EQUALS_RELOP, LESS_THAN_RELOP, NOT_EQUALS_RELOP

Constructor Summary

Constructors

Constructor and Description
IsNullNode()

Method Summary

Methods

Modifier and Type	Method and Description
(package private) void	bindParameter() Bind a ?
boolean	compareWithKnownConstant(Optimizable optTable, boolean considerParameters) Return whether this operator compares the given Optimizable with a constant whose value is known at compile time.
boolean	equalsComparisonWithConstantExpression(Optimizable optTable) Return whether this operator is an equality comparison of the given optimizable with a constant expression.
void	generateNegate(MethodBuilder mb, Optimizable optTable) Generate an expression that evaluates to true if the result of the comparison should be negated.
void	generateOperator(MethodBuilder mb, Optimizable optTable) Generate the comparison operator for this RelationalOperator.
DataValueDescriptor	getCompareValue(Optimizable optTable) Return an Object representing the known value that this relational operator is comparing to a column in the given Optimizable.
(package private) UnaryOperatorNode	getNegation(ValueNode operand) Negate the comparison.
int	getOperator() Return the operator (as an int) for this RelationalOperator.
java.lang.String	getReceiverInterfaceName() null operators are defined on DataValueDescriptor.
int	getStartOperator(Optimizable optTable) Get the start operator for a scan (at the store level) for this RelationalOperator.
int	getStopOperator(Optimizable optTable) Get the stop operator for a scan (at the store level) for this RelationalOperator.
RelationalOperator	getTransitiveSearchClause(ColumnReference otherCR) Return a relational operator which matches the current one but with the passed in ColumnReference as the (left) operand.
private boolean	isNotNullNode()
private boolean	isNullNode()
boolean	isRelationalOperator() Returns true if this ValueNode is a relational operator.
boolean	optimizableEqualityNode(Optimizable optTable, int columnNumber, boolean isNullOkay) Return true if the predicate represents an optimizable equality node.
double	selectivity(Optimizable optTable) IS NULL is like =, so should have the same selectivity
void	setNodeType(int nodeType) Set the node type for this node.
boolean	usefulStartKey(Optimizable optTable) Tell whether this relop is a useful start key for the given table.
boolean	usefulStopKey(Optimizable optTable) Tell whether this relop is a useful stop key for the given table.

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

bindComparisonOperator, bindExpression, eliminateNots, generateAbsoluteColumnId, generateExpressionOperand, generateOrderedNulls, generateQualMethod, generateRelativeColumnId, getColumnOperand, getColumnOperand, getExpressionOperand, getOperand, getOrderableVariantType, isQualifier, orderedNulls, selfComparison

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

acceptChildren, addXmlOpMethodParams, bindOperand, categorize, constantExpression, generateExpression, getOperand, getOperatorString, getOrderableVariantType, getParameterOperand, init, init, isConstantExpression, isEquivalent, preprocess, printSubNodes, remapColumnReferencesToExpressions, setMethodName, setOperator, toString

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

pushSqlXmlUtil

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

bindExpression, changeToCNF, checkIsBoolean, checkTopPredicatesForEqualsConditions, copyFields, evaluateConstantExpressions, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isInListProbeNode, isParameterNode, isSameNodeType, putAndsOnTop, requiresTypeFromContext, setCollationInfo, setCollationInfo, setCollationUsingCompilationSchema, setCollationUsingCompilationSchema, setNullability, setTransformed, setType, setType, setType, updatableByCursor, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop

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

accept, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, bindUserType, checkReliability, checkReliability, convertDefaultNode, createTypeDependency, debugFlush, debugPrint, disablePrivilegeCollection, formatNodeString, foundString, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContextManager, getCursorInfo, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getNodeFactory, getNodeType, getNullNode, getParameterTypes, getSchemaDescriptor, getSchemaDescriptor, getStatementType, getTableDescriptor, getTypeCompiler, init, init, init, init, init, init, init, init, init, init, init, isAtomic, isInstanceOf, isPrivilegeCollectionRequired, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, makeTableName, nodeHeader, orReliability, parseStatement, printLabel, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setContextManager, setEndOffset, setRefActionInfo, stackPrint, treePrint, treePrint, verifyClassExist

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.derby.impl.sql.compile.RelationalOperator

generateAbsoluteColumnId, generateExpressionOperand, generateOrderedNulls, generateQualMethod, generateRelativeColumnId, getColumnOperand, getColumnOperand, getExpressionOperand, getOperand, getOrderableVariantType, isQualifier, orderedNulls, selfComparison

Field Detail

nullValue

private DataValueDescriptor nullValue

Constructor Detail

IsNullNode

public IsNullNode()

Method Detail

setNodeType

public void setNodeType(int nodeType)

Description copied from class: QueryTreeNode

Set the node type for this node.

Overrides:

setNodeType in class QueryTreeNode

Parameters:

nodeType - The node type.

getNegation

UnaryOperatorNode getNegation(ValueNode operand)
                        throws StandardException

Negate the comparison.

Specified by:

getNegation in class UnaryComparisonOperatorNode

Parameters:

operand - The operand of the operator

Returns:

UnaryOperatorNode The negated expression

Throws:

StandardException - Thrown on error

bindParameter

void bindParameter()
             throws StandardException

Bind a ? parameter operand of the IS [NOT] NULL predicate.

Overrides:

bindParameter in class UnaryOperatorNode

Throws:

StandardException - Thrown on error

usefulStartKey

public boolean usefulStartKey(Optimizable optTable)

Description copied from interface: RelationalOperator

Tell whether this relop is a useful start key for the given table. It has already been determined that the relop has a column from the given table on one side or the other.

Specified by:

usefulStartKey in interface RelationalOperator

Parameters:

optTable - The Optimizable table for which we want to know whether this is a useful start key.

Returns:

true if this is a useful start key

See Also:

RelationalOperator.usefulStartKey(org.apache.derby.iapi.sql.compile.Optimizable)

usefulStopKey

public boolean usefulStopKey(Optimizable optTable)

Description copied from interface: RelationalOperator

Tell whether this relop is a useful stop key for the given table. It has already been determined that the relop has a column from the given table on one side or the other.

Specified by:

usefulStopKey in interface RelationalOperator

Parameters:

optTable - The Optimizable table for which we want to know whether this is a useful stop key.

Returns:

true if this is a useful stop key

See Also:

RelationalOperator.usefulStopKey(org.apache.derby.iapi.sql.compile.Optimizable)

getStartOperator

public int getStartOperator(Optimizable optTable)

Description copied from interface: RelationalOperator

Get the start operator for a scan (at the store level) for this RelationalOperator.

Specified by:

getStartOperator in interface RelationalOperator

Overrides:

getStartOperator in class UnaryComparisonOperatorNode

Parameters:

optTable - The optimizable table we're doing the scan on. This parameter is so we can tell which side of the operator the table's column is on.

Returns:

Either ScanController.GT or ScanController.GE

See Also:

RelationalOperator.getStartOperator(org.apache.derby.iapi.sql.compile.Optimizable)

getStopOperator

public int getStopOperator(Optimizable optTable)

Description copied from interface: RelationalOperator

Get the stop operator for a scan (at the store level) for this RelationalOperator.

Specified by:

getStopOperator in interface RelationalOperator

Overrides:

getStopOperator in class UnaryComparisonOperatorNode

Parameters:

optTable - The optimizable table we're doing the scan on. This parameter is so we can tell which side of the operator the table's column is on.

Returns:

Either ScanController.GT or ScanController.GE

See Also:

RelationalOperator.getStopOperator(org.apache.derby.iapi.sql.compile.Optimizable)

generateOperator

public void generateOperator(MethodBuilder mb,
                    Optimizable optTable)

Description copied from interface: RelationalOperator

Generate the comparison operator for this RelationalOperator. The operator can depend on which side of this operator the optimizable column is.

Specified by:

generateOperator in interface RelationalOperator

Parameters:

mb - The method the generated code is to go into

optTable - The optimizable table we're doing the scan on.

See Also:

RelationalOperator.generateOperator(org.apache.derby.iapi.services.compiler.MethodBuilder, org.apache.derby.iapi.sql.compile.Optimizable)

generateNegate

public void generateNegate(MethodBuilder mb,
                  Optimizable optTable)

Description copied from interface: RelationalOperator

Generate an expression that evaluates to true if the result of the comparison should be negated. For example, col > 1 generates a comparison operator of <= and a negation of true, while col < 1 generates a comparison operator of < and a negation of false.

Specified by:

generateNegate in interface RelationalOperator

Parameters:

mb - The method the generated code is to go into

optTable - The Optimizable table the Qualifier will qualify

See Also:

RelationalOperator.generateNegate(org.apache.derby.iapi.services.compiler.MethodBuilder, org.apache.derby.iapi.sql.compile.Optimizable)

getOperator

public int getOperator()

Description copied from interface: RelationalOperator

Return the operator (as an int) for this RelationalOperator.

Specified by:

getOperator in interface RelationalOperator

Returns:

int The operator for this RelationalOperator.

See Also:

RelationalOperator.getOperator()

compareWithKnownConstant

public boolean compareWithKnownConstant(Optimizable optTable,
                               boolean considerParameters)

Description copied from interface: RelationalOperator

Return whether this operator compares the given Optimizable with a constant whose value is known at compile time.

Specified by:

compareWithKnownConstant in interface RelationalOperator

See Also:

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

getCompareValue

public DataValueDescriptor getCompareValue(Optimizable optTable)
                                    throws StandardException

Description copied from interface: RelationalOperator

Return an Object representing the known value that this relational operator is comparing to a column in the given Optimizable.

Specified by:

getCompareValue in interface RelationalOperator

Throws:

StandardException - Thrown on error

See Also:

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

equalsComparisonWithConstantExpression

public boolean equalsComparisonWithConstantExpression(Optimizable optTable)

Description copied from interface: RelationalOperator

Return whether this operator is an equality comparison of the given optimizable with a constant expression.

Specified by:

equalsComparisonWithConstantExpression in interface RelationalOperator

See Also:

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

getTransitiveSearchClause

public RelationalOperator getTransitiveSearchClause(ColumnReference otherCR)
                                             throws StandardException

Description copied from interface: RelationalOperator

Return a relational operator which matches the current one but with the passed in ColumnReference as the (left) operand.

Specified by:

getTransitiveSearchClause in interface RelationalOperator

Parameters:

otherCR - The ColumnReference for the new (left) operand.

Returns:

A relational operator which matches the current one but with the passed in ColumnReference as the (left) operand.

Throws:

StandardException - thrown on error

See Also:

RelationalOperator.getTransitiveSearchClause(org.apache.derby.impl.sql.compile.ColumnReference)

getReceiverInterfaceName

public java.lang.String getReceiverInterfaceName()

null operators are defined on DataValueDescriptor. Overrides method in UnaryOperatorNode for code generation purposes.

Overrides:

getReceiverInterfaceName in class UnaryOperatorNode

selectivity

public double selectivity(Optimizable optTable)

IS NULL is like =, so should have the same selectivity

Overrides:

selectivity in class ValueNode

isNullNode

private boolean isNullNode()

isNotNullNode

private boolean isNotNullNode()

isRelationalOperator

public boolean isRelationalOperator()

Description copied from class: ValueNode

Returns true if this ValueNode is a relational operator. Relational Operators are <, <=, =, >, >=, <> as well as IS NULL and IS NOT NULL. This is the preferred way of figuring out if a ValueNode is relational or not.

Overrides:

isRelationalOperator in class ValueNode

See Also:

ValueNode.isRelationalOperator()

optimizableEqualityNode

public boolean optimizableEqualityNode(Optimizable optTable,
                              int columnNumber,
                              boolean isNullOkay)

Description copied from class: ValueNode

Return true if the predicate represents an optimizable equality node. an expression is considered to be an optimizable equality node if all the following conditions are met:

1. the operator is an = or IS NULL operator
2. one of the operands is a column specified by optTable/columnNumber
3. Both operands are not the same column; i.e tab.col = tab.col
4. There are no implicit varchar comparisons of the operands; i.e either both operands are string like (varchar, char, longvarchar) or neither operand is string like

Overrides:

optimizableEqualityNode in class ValueNode

Parameters:

optTable - the table being optimized. Column reference must be from this table.

columnNumber - the column number. One of the operands of this predicate must be the column number specified by optTable/columnNumber

isNullOkay - if set to true we also consider IS NULL predicates; otherwise consider only = predicates.

See Also:

ValueNode.optimizableEqualityNode(org.apache.derby.iapi.sql.compile.Optimizable, int, boolean)