org.apache.derby.impl.sql.compile

Class BinaryRelationalOperatorNode

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.BinaryOperatorNode

org.apache.derby.impl.sql.compile.BinaryComparisonOperatorNode

org.apache.derby.impl.sql.compile.BinaryRelationalOperatorNode

All Implemented Interfaces:

Node, Visitable, RelationalOperator

public class BinaryRelationalOperatorNode
extends BinaryComparisonOperatorNode
implements RelationalOperator

This class represents the 6 binary operators: LessThan, LessThanEquals, Equals, NotEquals, GreaterThan and GreaterThanEquals.

Field Summary

Fields

Modifier and Type	Field and Description
private BaseTableNumbersVisitor	btnVis
private InListOperatorNode	inListProbeSource
protected static int	LEFT
protected static int	NEITHER
private int	operatorType
(package private) JBitSet	optBaseTables
protected static int	RIGHT
(package private) JBitSet	valNodeBaseTables

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

AND, BinaryArgTypes, BinaryMethodNames, BinaryOperators, BinaryResultTypes, CONCATENATE, DIVIDE, EQ, GE, GT, LE, leftInterfaceType, leftOperand, LIKE, LT, methodName, MINUS, NE, operator, OR, PLUS, receiver, resultInterfaceType, rightInterfaceType, rightOperand, TIMES, XMLEXISTS_OP, XMLQUERY_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
BinaryRelationalOperatorNode()

Method Summary

Methods

Modifier and Type	Method and Description
protected double	booleanSelectivity(Optimizable optTable) Return 50% if this is a comparison with a boolean column, a negative selectivity otherwise.
private void	buildTableNumList(FromTable ft, boolean forPush) Create a set of table numbers to search when trying to find which (if either) of this operator's operands reference the received target table.
protected int	columnOnOneSide(Optimizable optTable) Determine whether there is a column from the given table on one side of this operator, and if so, which side is it on?
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.
(package private) ValueNode	evaluateConstantExpressions() See if the node always evaluates to true or false, and return a Boolean constant node if it does.
void	generateAbsoluteColumnId(MethodBuilder mb, Optimizable optTable) Generate the absolute column id for the ColumnReference that appears on one side of this RelationalOperator or the other, and that refers to the given table.
void	generateExpressionOperand(Optimizable optTable, int columnPosition, ExpressionClassBuilder acb, MethodBuilder mb) Check whether this RelationalOperator is a comparison of the given column with an 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.
void	generateOrderedNulls(MethodBuilder mb) Generate an expression that evaluates to true if this RelationalOperator uses ordered null semantics, false if it doesn't.
void	generateQualMethod(ExpressionClassBuilder acb, MethodBuilder mb, Optimizable optTable) Generate the method to evaluate a Qualifier.
void	generateRelativeColumnId(MethodBuilder mb, Optimizable optTable) Generate the relative column id for the ColumnReference that appears on one side of this RelationalOperator or the other, and that refers to the given table.
ValueNode	genSQLJavaSQLTree() generate a SQL->Java->SQL conversion tree above the left and right operand of this Binary Operator Node if needed.
private int	getAbsoluteColumnPosition(Optimizable optTable) Get the absolute 0-based column position of the ColumnReference from the conglomerate for this Optimizable.
ColumnReference	getColumnOperand(Optimizable optTable) Get the ColumnReference for the given table on one side of this RelationalOperator.
ColumnReference	getColumnOperand(Optimizable optTable, int columnPosition) Check whether this RelationalOperator is a comparison of the given column with an expression.
DataValueDescriptor	getCompareValue(Optimizable optTable) Return an Object representing the known value that this relational operator is comparing to a column in the given Optimizable.
ValueNode	getExpressionOperand(int tableNumber, int columnPosition, FromTable ft) Check whether this RelationalOperator is a comparison of the given column with an expression.
protected InListOperatorNode	getInListOp() If this rel op was created for an IN-list probe predicate then return the underlying InListOperatorNode.
(package private) BinaryOperatorNode	getNegation(ValueNode leftOperand, ValueNode rightOperand) Returns the negation of this operator; negation of Equals is NotEquals.
private int	getNegationNode()
private int	getNodeTypeForSwap() Return the node type that must be used in order to construct an equivalent expression if the operands are swapped.
ValueNode	getOperand(ColumnReference cRef, int refSetSize, boolean otherSide) Find the operand (left or right) that points to the same table as the received ColumnReference, and then return either that operand or the "other" operand, depending on the value of otherSide.
int	getOperator() Return the operator (as an int) for this RelationalOperator.
int	getOrderableVariantType(Optimizable optTable) Return the variant type for the Qualifier's Orderable.
java.lang.String	getReceiverInterfaceName() The methods generated for this node all are on Orderable.
ValueNode	getScopedOperand(int whichSide, JBitSet parentRSNsTables, ResultSetNode childRSN, int[] whichRC) Take a ResultSetNode and return a column reference that is scoped for for the received ResultSetNode, where "scoped" means that the column reference points to a specific column in the RSN.
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.
(package private) BinaryOperatorNode	getSwappedEquivalent() Return an equivalent node with the operands swapped, and possibly with the operator type changed in order to preserve the meaning of the expression.
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	implicitVarcharComparison() Return whether or not this binary relational predicate requires an implicit (var)char conversion.
void	init(java.lang.Object leftOperand, java.lang.Object rightOperand, java.lang.Object forQueryRewrite) Initializer for a BinaryOperatorNode
void	init(java.lang.Object leftOperand, java.lang.Object rightOperand, java.lang.Object inListOp, java.lang.Object forQueryRewrite) Same as init() above except takes a third argument that is an InListOperatorNode.
private void	initBaseTableVisitor(int numTablesInQuery, boolean initOptBaseTables) Initialize the fields used for retrieving base tables in subtrees, which allows us to do a more extensive search for table references.
boolean	isBinaryEqualsOperatorNode() Returns true if this value node is a equals operator.
boolean	isInListProbeNode() Returns true if this value node is an operator created for optimized performance of an IN list.
boolean	isQualifier(Optimizable optTable, boolean forPush) Return true if this operator can be compiled into a Qualifier for the given Optimizable table.
boolean	isRelationalOperator() Returns true if this ValueNode is a relational operator.
protected boolean	keyColumnOnLeft(Optimizable optTable) Return true if a key column for the given table is found on the left side of this operator, false if it is found on the right side of this operator.
private ValueNode	newBool(boolean b) Create a Boolean constant node with a specified value.
boolean	optimizableEqualityNode(Optimizable optTable, int columnNumber, boolean isNullOkay) Return true if the predicate represents an optimizable equality node.
boolean	orderedNulls() Return true if this operator uses ordered null semantics
double	selectivity(Optimizable optTable) return the selectivity of this predicate.
boolean	selfComparison(ColumnReference cr) Check whether this RelationalOperator compares the given ColumnReference to any columns in the same table as the ColumnReference.
protected boolean	usefulStartKey(boolean columnOnLeft) is this is useful start key?
boolean	usefulStartKey(Optimizable optTable) Tell whether this relop is a useful start key for the given table.
protected boolean	usefulStopKey(boolean columnOnLeft)
boolean	usefulStopKey(Optimizable optTable) Tell whether this relop is a useful stop key for the given table.
private boolean	valNodeReferencesOptTable(ValueNode valNode, FromTable optTable, boolean forPush, boolean walkOptTableSubtree) Determine whether or not the received ValueNode (which will usually be a ColumnReference) references either the received optTable or else a base table in the subtree beneath that optTable.

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

bindComparisonOperator, bindExpression, changeToCNF, eliminateNots, getBetweenSelectivity, getForQueryRewrite, init, preprocess, setBetweenSelectivity, setForQueryRewrite

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

acceptChildren, bindXMLQuery, categorize, constantExpression, generateExpression, getLeftOperand, getOrderableVariantType, getRightOperand, init, isConstantExpression, isEquivalent, printSubNodes, remapColumnReferencesToExpressions, setLeftOperand, setLeftRightInterfaceType, setMethodName, setOperator, setRightOperand, 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, checkIsBoolean, checkTopPredicatesForEqualsConditions, copyFields, genEqualsFalseTree, generate, generateFilter, genIsNullTree, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, isBooleanFalse, isBooleanTrue, isCloneable, 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, isAtomic, isInstanceOf, isPrivilegeCollectionRequired, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, makeTableName, nodeHeader, orReliability, parseStatement, printLabel, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setContextManager, setEndOffset, setNodeType, setRefActionInfo, stackPrint, treePrint, treePrint, verifyClassExist

Methods inherited from class java.lang.Object

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

Field Detail

operatorType

private int operatorType

btnVis

private BaseTableNumbersVisitor btnVis

optBaseTables

JBitSet optBaseTables

valNodeBaseTables

JBitSet valNodeBaseTables

inListProbeSource

private InListOperatorNode inListProbeSource

LEFT

protected static final int LEFT

See Also:

Constant Field Values

NEITHER

protected static final int NEITHER

See Also:

Constant Field Values

RIGHT

protected static final int RIGHT

See Also:

Constant Field Values

Constructor Detail

BinaryRelationalOperatorNode

public BinaryRelationalOperatorNode()

Method Detail

init

public void init(java.lang.Object leftOperand,
        java.lang.Object rightOperand,
        java.lang.Object forQueryRewrite)

Description copied from class: BinaryOperatorNode

Initializer for a BinaryOperatorNode

Specified by:

init in interface Node

Overrides:

init in class BinaryOperatorNode

Parameters:

leftOperand - The left operand of the node

rightOperand - The right operand of the node

forQueryRewrite - An Integer holding the operatorType for this operator.

init

public void init(java.lang.Object leftOperand,
        java.lang.Object rightOperand,
        java.lang.Object inListOp,
        java.lang.Object forQueryRewrite)

Same as init() above except takes a third argument that is an InListOperatorNode. This version is used during IN-list preprocessing to create a "probe predicate" for the IN-list. See InListOperatorNode.preprocess() for more. DERBY-6185 (Query against view with "where name LIKE 'Col1' ESCAPE '\' " failed) 4th argument forQueryRewrite can be true only if this node has been added by an internal rewrite of the query. This allows binding to be more liberal when checking it against allowed syntax. This parameter will be passed FALSE when a new instance of the node is being created(which is the majority of the cases). But when an existing node is getting cloned, the value of this parameter should be passed as the originalNode.getForQueryRewrite(). Examples of this can be found in Predicate.Java and PredicateList.java

Specified by:

init in interface Node

Overrides:

init in class BinaryOperatorNode

getInListOp

protected InListOperatorNode getInListOp()

If this rel op was created for an IN-list probe predicate then return the underlying InListOperatorNode. Will return null if this rel op is a "legitimate" relational operator (as opposed to a disguised IN-list). With the exception of nullability checking via the isInListProbeNode() method, all access to this.inListProbeSource MUST come through this method, as this method ensures that the left operand of the inListProbeSource is set correctly before returning it.

getColumnOperand

public ColumnReference getColumnOperand(Optimizable optTable,
                               int columnPosition)

Description copied from interface: RelationalOperator

Check whether this RelationalOperator is a comparison of the given column with an expression. If so, return the ColumnReference that corresponds to the given column, and that is on one side of this RelationalOperator or the other (this method copes with the column being on either side of the operator). If the given column does not appear by itself on one side of the comparison, the method returns null.

Specified by:

getColumnOperand in interface RelationalOperator

Parameters:

optTable - An Optimizable for the base table the column is in

columnPosition - The ordinal position of the column (one-based)

Returns:

The ColumnReference on one side of this RelationalOperator that represents the given columnPosition. Returns null if no such ColumnReference exists by itself on one side of this RelationalOperator.

See Also:

RelationalOperator.getColumnOperand(org.apache.derby.iapi.sql.compile.Optimizable, int)

getColumnOperand

public ColumnReference getColumnOperand(Optimizable optTable)

Description copied from interface: RelationalOperator

Get the ColumnReference for the given table on one side of this RelationalOperator. This presumes it will be found only on one side. If not found, it will return null.

Specified by:

getColumnOperand in interface RelationalOperator

See Also:

RelationalOperator.getColumnOperand(org.apache.derby.iapi.sql.compile.Optimizable, int)

getExpressionOperand

public ValueNode getExpressionOperand(int tableNumber,
                             int columnPosition,
                             FromTable ft)

Description copied from interface: RelationalOperator

Check whether this RelationalOperator is a comparison of the given column with an expression. If so, return the expression the column is being compared to.

Specified by:

getExpressionOperand in interface RelationalOperator

Parameters:

tableNumber - The table number of the base table the column is in

columnPosition - The ordinal position of the column (one-based)

ft - We'll look for the column in all tables at and beneath ft. This is useful if ft is, say, a ProjectRestrictNode over a subquery-- then we want to look at all of the FROM tables in the subquery to try to find the right column.

Returns:

The ValueNode for the expression the column is being compared to - null if the column is not being compared to anything.

See Also:

RelationalOperator.getExpressionOperand(int, int, org.apache.derby.impl.sql.compile.FromTable)

getOperand

public ValueNode getOperand(ColumnReference cRef,
                   int refSetSize,
                   boolean otherSide)

Description copied from interface: RelationalOperator

Find the operand (left or right) that points to the same table as the received ColumnReference, and then return either that operand or the "other" operand, depending on the value of otherSide. This presumes it will be found only on one side. If not found, it will return null.

Specified by:

getOperand in interface RelationalOperator

Parameters:

cRef - The ColumnReference for which we're searching.

refSetSize - Size of the referenced map for the predicate represented by this RelationalOperator node. This is used for storing base table numbers when searching for cRef.

otherSide - Assuming we find an operand that points to the same table as cRef, then we will return the *other* operand if otherSide is true; else we'll return the operand that matches cRef.

See Also:

RelationalOperator.getOperand(org.apache.derby.impl.sql.compile.ColumnReference, int, boolean)

generateExpressionOperand

public void generateExpressionOperand(Optimizable optTable,
                             int columnPosition,
                             ExpressionClassBuilder acb,
                             MethodBuilder mb)
                               throws StandardException

Description copied from interface: RelationalOperator

Check whether this RelationalOperator is a comparison of the given column with an expression. If so, generate the Expression for the ValueNode that the column is being compared to.

Specified by:

generateExpressionOperand in interface RelationalOperator

Parameters:

optTable - An Optimizable for the base table the column is in

columnPosition - The ordinal position of the column (one-based)

acb - The ExpressionClassBuilder for the class we're building

mb - The method the expression will go into

Throws:

StandardException - Thrown on error

See Also:

RelationalOperator.generateExpressionOperand(org.apache.derby.iapi.sql.compile.Optimizable, int, org.apache.derby.impl.sql.compile.ExpressionClassBuilder, org.apache.derby.iapi.services.compiler.MethodBuilder)

selfComparison

public boolean selfComparison(ColumnReference cr)
                       throws StandardException

Description copied from interface: RelationalOperator

Check whether this RelationalOperator compares the given ColumnReference to any columns in the same table as the ColumnReference.

Specified by:

selfComparison in interface RelationalOperator

Parameters:

cr - The ColumnReference that is being compared to some expression.

Returns:

true if the given ColumnReference is being compared to any columns from the same table

Throws:

StandardException - Thrown on error

See Also:

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

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)

keyColumnOnLeft

protected boolean keyColumnOnLeft(Optimizable optTable)

Return true if a key column for the given table is found on the left side of this operator, false if it is found on the right side of this operator. NOTE: This method assumes that a key column will be found on one side or the other. If you don't know whether a key column exists, use the columnOnOneSide() method (below).

Parameters:

optTable - The Optimizable table that we're looking for a key column on.

Returns:

true if a key column for the given table is on the left side of this operator, false if one is found on the right side of this operator.

columnOnOneSide

protected int columnOnOneSide(Optimizable optTable)

Determine whether there is a column from the given table on one side of this operator, and if so, which side is it on?

Parameters:

optTable - The Optimizable table that we're looking for a key column on.

Returns:

LEFT if there is a column on the left, RIGHT if there is a column on the right, NEITHER if no column found on either side.

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)

generateAbsoluteColumnId

public void generateAbsoluteColumnId(MethodBuilder mb,
                            Optimizable optTable)

Description copied from interface: RelationalOperator

Generate the absolute column id for the ColumnReference that appears on one side of this RelationalOperator or the other, and that refers to the given table. (Absolute column id means column id within the row stored on disk.)

Specified by:

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

generateRelativeColumnId

public void generateRelativeColumnId(MethodBuilder mb,
                            Optimizable optTable)

Description copied from interface: RelationalOperator

Generate the relative column id for the ColumnReference that appears on one side of this RelationalOperator or the other, and that refers to the given table. (Relative column id means column id within the partial row returned by the store.)

Specified by:

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

getAbsoluteColumnPosition

private int getAbsoluteColumnPosition(Optimizable optTable)

Get the absolute 0-based column position of the ColumnReference from the conglomerate for this Optimizable.

Parameters:

optTable - The Optimizable

Returns:

The absolute 0-based column position of the ColumnReference

generateQualMethod

public void generateQualMethod(ExpressionClassBuilder acb,
                      MethodBuilder mb,
                      Optimizable optTable)
                        throws StandardException

Description copied from interface: RelationalOperator

Generate the method to evaluate a Qualifier. The factory method for a Qualifier takes a GeneratedMethod that returns the Orderable that Qualifier.getOrderable() returns.

Specified by:

generateQualMethod in interface RelationalOperator

Parameters:

acb - The ExpressionClassBuilder for the class we're building

mb - The method the generated code is to go into

optTable - The Optimizable table the Qualifier will qualify

Throws:

StandardException - Thrown on error

generateOrderedNulls

public void generateOrderedNulls(MethodBuilder mb)

Description copied from interface: RelationalOperator

Generate an expression that evaluates to true if this RelationalOperator uses ordered null semantics, false if it doesn't.

Specified by:

generateOrderedNulls in interface RelationalOperator

Parameters:

mb - The method the generated code is to go into

See Also:

RelationalOperator.generateOrderedNulls(org.apache.derby.iapi.services.compiler.MethodBuilder)

orderedNulls

public boolean orderedNulls()

Description copied from interface: RelationalOperator

Return true if this operator uses ordered null semantics

Specified by:

orderedNulls in interface RelationalOperator

See Also:

RelationalOperator.orderedNulls()

isQualifier

public boolean isQualifier(Optimizable optTable,
                  boolean forPush)
                    throws StandardException

Description copied from interface: RelationalOperator

Return true if this operator can be compiled into a Qualifier for the given Optimizable table. This means that there is a column from that table on one side of this relop, and an expression that does not refer to the table on the other side of the relop. Note that this method has two uses: 1) see if this operator (or more specifically, the predicate to which this operator belongs) can be used as a join predicate (esp. for a hash join), and 2) see if this operator can be pushed to the target optTable. We use the parameter "forPush" to distinguish between the two uses because in some cases (esp. situations where we have subqueries) the answer to "is this a qualifier?" can differ depending on whether or not we're pushing. In particular, for binary ops that are join predicates, if we're just trying to find an equijoin predicate then this op qualifies if it references either the target table OR any of the base tables in the table's subtree. But if we're planning to push the predicate down to the target table, this op only qualifies if it references the target table directly. This difference in behavior is required because in case 1 (searching for join predicates), the operator remains at its current level in the tree even if its operands reference nodes further down; in case 2, though, we'll end up pushing the operator down the tree to child node(s) and that requires additional logic, such as "scoping" consideration. Until that logic is in place, we don't search a subtree if the intent is to push the predicate to which this operator belongs further down that subtree. See BinaryRelationalOperatorNode for an example of where this comes into play.

Specified by:

isQualifier in interface RelationalOperator

Parameters:

optTable - The Optimizable table in question.

forPush - Are we asking because we're trying to push?

Returns:

true if this operator can be compiled into a Qualifier for the given Optimizable table.

Throws:

StandardException - Thrown on error

See Also:

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

getOrderableVariantType

public int getOrderableVariantType(Optimizable optTable)
                            throws StandardException

Description copied from interface: RelationalOperator

Return the variant type for the Qualifier's Orderable. (Is the Orderable invariant within a scan or within a query?)

Specified by:

getOrderableVariantType in interface RelationalOperator

Parameters:

optTable - The Optimizable table the Qualifier will qualify

Returns:

int The variant type for the Qualifier's Orderable.

Throws:

StandardException - thrown on error

See Also:

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

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)

booleanSelectivity

protected double booleanSelectivity(Optimizable optTable)
                             throws StandardException

Return 50% if this is a comparison with a boolean column, a negative selectivity otherwise.

Throws:

StandardException

getReceiverInterfaceName

public java.lang.String getReceiverInterfaceName()

The methods generated for this node all are on Orderable. Overrides this method in BooleanOperatorNode for code generation purposes.

Overrides:

getReceiverInterfaceName in class BinaryOperatorNode

evaluateConstantExpressions

ValueNode evaluateConstantExpressions()
                                throws StandardException

See if the node always evaluates to true or false, and return a Boolean constant node if it does.

Overrides:

evaluateConstantExpressions in class ValueNode

Returns:

a node representing a Boolean constant if the result of the operator is known; otherwise, this operator node

Throws:

StandardException - if an error occurs during evaluation

See Also:

ConstantExpressionVisitor

newBool

private ValueNode newBool(boolean b)
                   throws StandardException

Create a Boolean constant node with a specified value.

Parameters:

b - the value of the constant

Returns:

a node representing a Boolean constant

Throws:

StandardException

getNegation

BinaryOperatorNode getNegation(ValueNode leftOperand,
                             ValueNode rightOperand)
                         throws StandardException

Returns the negation of this operator; negation of Equals is NotEquals.

Specified by:

getNegation in class BinaryComparisonOperatorNode

Parameters:

leftOperand - The left operand of the comparison operator

rightOperand - The right operand of the comparison operator

Returns:

BinaryOperatorNode The negated expression

Throws:

StandardException - Thrown on error

getNegationNode

private int getNegationNode()

getSwappedEquivalent

BinaryOperatorNode getSwappedEquivalent()
                                  throws StandardException

Return an equivalent node with the operands swapped, and possibly with the operator type changed in order to preserve the meaning of the expression.

Specified by:

getSwappedEquivalent in class BinaryComparisonOperatorNode

Returns:

an equivalent expression with the operands swapped

Throws:

StandardException - if an error occurs

getNodeTypeForSwap

private int getNodeTypeForSwap()

Return the node type that must be used in order to construct an equivalent expression if the operands are swapped. For symmetric operators (= and <>), the same node type is returned. Otherwise, the direction of the operator is switched in order to preserve the meaning (for instance, a node representing less-than will return the node type for greater-than).

Returns:

a node type that preserves the meaning of the expression if the operands are swapped

usefulStartKey

protected boolean usefulStartKey(boolean columnOnLeft)

is this is useful start key? for example a predicate of the from column Lessthan 5 is not a useful start key but is a useful stop key. However 5 Lessthan column is a useful start key.

Parameters:

columnOnLeft - is true if the column is the left hand side of the binary operator.

usefulStopKey

protected boolean usefulStopKey(boolean columnOnLeft)

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

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

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()

selectivity

public double selectivity(Optimizable optTable)
                   throws StandardException

return the selectivity of this predicate.

Overrides:

selectivity in class ValueNode

Throws:

StandardException

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)

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

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()

isBinaryEqualsOperatorNode

public boolean isBinaryEqualsOperatorNode()

Description copied from class: ValueNode

Returns true if this value node is a equals operator.

Overrides:

isBinaryEqualsOperatorNode in class ValueNode

See Also:

ValueNode.isBinaryEqualsOperatorNode()

isInListProbeNode

public boolean isInListProbeNode()

Description copied from class: ValueNode

Returns true if this value node is an operator created for optimized performance of an IN list. Or more specifically, returns true if this value node is an equals operator of the form "col = ?" that we generated during preprocessing to allow index multi-probing.

Overrides:

isInListProbeNode in class ValueNode

See Also:

It's okay for this method to reference inListProbeSource directly because it does not rely on the contents of inListProbeSource's leftOperand, and a caller of this method cannot gain access to inListProbeSource's leftOperand through this method.

optimizableEqualityNode

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

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.

Throws:

StandardException

See Also:

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

implicitVarcharComparison

private boolean implicitVarcharComparison()
                                   throws StandardException

Return whether or not this binary relational predicate requires an implicit (var)char conversion. This is important when considering hash join since this type of equality predicate is not currently supported for a hash join.

Returns:

Whether or not an implicit (var)char conversion is required for this binary relational operator.

Throws:

StandardException - Thrown on error

genSQLJavaSQLTree

public ValueNode genSQLJavaSQLTree()
                            throws StandardException

Description copied from class: BinaryOperatorNode

generate a SQL->Java->SQL conversion tree above the left and right operand of this Binary Operator Node if needed. Subclasses can override the default behavior.

Overrides:

genSQLJavaSQLTree in class BinaryComparisonOperatorNode

Returns:

ValueNode The new tree.

Throws:

StandardException - Thrown on error

See Also:

BinaryOperatorNode.genSQLJavaSQLTree()

getScopedOperand

public ValueNode getScopedOperand(int whichSide,
                         JBitSet parentRSNsTables,
                         ResultSetNode childRSN,
                         int[] whichRC)
                           throws StandardException

Take a ResultSetNode and return a column reference that is scoped for for the received ResultSetNode, where "scoped" means that the column reference points to a specific column in the RSN. This is used for remapping predicates from an outer query down to a subquery. For example, assume we have the following query: select * from (select i,j from t1 union select i,j from t2) X1, (select a,b from t3 union select a,b from t4) X2 where X1.j = X2.b; Then assume that this BinaryRelationalOperatorNode represents the "X1.j = X2.b" predicate and that the childRSN we received as a parameter represents one of the subqueries to which we want to push the predicate; let's say it's: select i,j from t1 Then what we want to do in this method is map one of the operands X1.j or X2.b (depending on the 'whichSide' parameter) to the childRSN, if possible. Note that in our example, "X2.b" should _NOT_ be mapped because it doesn't apply to the childRSN for the subquery "select i,j from t1"; thus we should leave it as it is. "X1.j", however, _does_ need to be scoped, and so this method will return a ColumnReference pointing to "T1.j" (or whatever the corresponding column in T1 is). ASSUMPTION: We should only get to this method if we know that exactly one operand in the predicate to which this operator belongs can and should be mapped to the received childRSN.

Parameters:

whichSide - The operand are we trying to scope (LEFT or RIGHT)

parentRSNsTables - Set of all table numbers referenced by the ResultSetNode that is _parent_ to the received childRSN. We need this to make sure we don't scope the operand to a ResultSetNode to which it doesn't apply.

childRSN - The result set node to which we want to create a scoped predicate.

whichRC - If not -1 then this tells us which ResultColumn in the received childRSN we need to use for the scoped predicate; if -1 then the column position of the scoped column reference will be stored in this array and passed back to the caller.

Returns:

A column reference scoped to the received childRSN, if possible. If the operand is a ColumnReference that is not supposed to be scoped, we return a _clone_ of the reference--this is necessary because the reference is going to be pushed to two places (left and right children of the parentRSN) and if both children are referencing the same instance of the column reference, they'll interfere with each other during optimization.

Throws:

StandardException

valNodeReferencesOptTable

private boolean valNodeReferencesOptTable(ValueNode valNode,
                                FromTable optTable,
                                boolean forPush,
                                boolean walkOptTableSubtree)

Determine whether or not the received ValueNode (which will usually be a ColumnReference) references either the received optTable or else a base table in the subtree beneath that optTable.

Parameters:

valNode - The ValueNode that has the reference(s).

optTable - The table/subtree node to which we're trying to find a reference.

forPush - Whether or not we are searching with the intent to push this operator to the target table.

walkOptTableSubtree - Should we walk the subtree beneath optTable to find base tables, or not? Will be false if we've already done it for the left operand and now we're here for the right operand.

Returns:

True if valNode contains a reference to optTable or to a base table in the subtree beneath optTable; false otherwise.

initBaseTableVisitor

private void initBaseTableVisitor(int numTablesInQuery,
                        boolean initOptBaseTables)

Initialize the fields used for retrieving base tables in subtrees, which allows us to do a more extensive search for table references. If the fields have already been created, then just reset their values.

Parameters:

numTablesInQuery - Used for creating JBitSets that can hold table numbers for the query.

initOptBaseTables - Whether or not we should clear out or initialize the optBaseTables bit set.

buildTableNumList

private void buildTableNumList(FromTable ft,
                     boolean forPush)
                        throws StandardException

Create a set of table numbers to search when trying to find which (if either) of this operator's operands reference the received target table. At the minimum this set should contain the target table's own table number. After that, if we're _not_ attempting to push this operator (or more specifically, the predicate to which this operator belongs) to the target table, we go on to search the subtree beneath the target table and add any base table numbers to the searchable list.

Parameters:

ft - Target table for which we're building the search list.

forPush - Whether or not we are searching with the intent to push this operator to the target table.

Throws:

StandardException