org.apache.derby.impl.sql.compile

Class UserTypeConstantNode

java.lang.Object

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

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

org.apache.derby.impl.sql.compile.ConstantNode

org.apache.derby.impl.sql.compile.UserTypeConstantNode

All Implemented Interfaces:

Node, Visitable

public class UserTypeConstantNode
extends ConstantNode

User type constants. These are created by built-in types that use user types as their implementation. This could also potentially be used by an optimizer that wanted to store plans for frequently-used parameter values. This is also used to represent nulls in user types, which occurs when NULL is inserted into or supplied as the update value for a usertype column.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) java.lang.Object	value

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

Constructor Summary

Constructors

Constructor and Description
UserTypeConstantNode()

Method Summary

Methods

Modifier and Type	Method and Description
(package private) void	generateConstant(ExpressionClassBuilder acb, MethodBuilder mb) Should never be called for UserTypeConstantNode because we have our own generateExpression().
void	generateExpression(ExpressionClassBuilder acb, MethodBuilder mb) For a UserTypeConstantNode, we have to store away the object somewhere and have a way to get it back at runtime.
java.lang.Object	getConstantValueAsObject() Return an Object representing the bind time value of this expression tree.
java.lang.Object	getObjectValue() Return the object value of this user defined type.
void	init(java.lang.Object arg1) Initializer for a typed null node or a date, time, or timestamp value.
boolean	isNull() Return whether or not this node represents a typed null constant.

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

bindExpression, constantExpression, getClone, getOrderableVariantType, getValue, init, isCloneable, isConstantExpression, isEquivalent, setValue, toString

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

bindExpression, categorize, changeToCNF, checkIsBoolean, checkTopPredicatesForEqualsConditions, copyFields, eliminateNots, evaluateConstantExpressions, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getColumnName, getDataValueFactory, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isInListProbeNode, isParameterNode, isRelationalOperator, isSameNodeType, optimizableEqualityNode, preprocess, putAndsOnTop, remapColumnReferencesToExpressions, requiresTypeFromContext, selectivity, 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, acceptChildren, 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, printSubNodes, 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

value

java.lang.Object value

Constructor Detail

UserTypeConstantNode

public UserTypeConstantNode()

Method Detail

init

public void init(java.lang.Object arg1)
          throws StandardException

Initializer for a typed null node or a date, time, or timestamp value. Parameters may be:

• arg1 The TypeId for the type of the node
• arg2 The factory to get the TypeId and DataTypeServices factories from.

- OR -

• arg1 the date, time, or timestamp value

Specified by:

init in interface Node

Overrides:

init in class QueryTreeNode

Throws:

StandardException - thrown on failure

getObjectValue

public java.lang.Object getObjectValue()

Return the object value of this user defined type.

Returns:

the value of this constant. can't use getValue() for this. getValue() returns the DataValueDescriptor for the built-in types that are implemented as user types (date, time, timestamp)

isNull

public boolean isNull()

Return whether or not this node represents a typed null constant.

Overrides:

isNull in class ConstantNode

getConstantValueAsObject

public java.lang.Object getConstantValueAsObject()

Return an Object representing the bind time value of this expression tree. If the expression tree does not evaluate to a constant at bind time then we return null. This is useful for bind time resolution of VTIs. RESOLVE: What do we do for primitives?

Overrides:

getConstantValueAsObject in class ValueNode

Returns:

An Object representing the bind time value of this expression tree. (null if not a bind time constant.)

generateExpression

public void generateExpression(ExpressionClassBuilder acb,
                      MethodBuilder mb)
                        throws StandardException

For a UserTypeConstantNode, we have to store away the object somewhere and have a way to get it back at runtime. These objects are serializable. This gives us at least two options: 1) serialize it out into a byte array field, and serialize it back in when needed, from the field. 2) have an array of objects in the prepared statement and a #, to find the object directly. Because it is serializable, it will store with the rest of the executable just fine. Choice 2 gives better performance -- the ser/deser cost is paid on database access for the statement, not for each execution of it. However, it requires some infrastructure support from prepared statements. For now, we take choice 3, and make some assumptions about available methods on the user type. This choice has the shortcoming that it will not work for arbitrary user types. REVISIT and implement choice 2 when a general solution is needed.

A null is generated as a Null value cast to the type of the constant node.

Overrides:

generateExpression in class ConstantNode

Parameters:

acb - The ExpressionClassBuilder for the class being built

mb - The method the expression will go into

Throws:

StandardException - Thrown on error

generateConstant

void generateConstant(ExpressionClassBuilder acb,
                    MethodBuilder mb)
                throws StandardException

Should never be called for UserTypeConstantNode because we have our own generateExpression().

Specified by:

generateConstant in class ConstantNode

Parameters:

acb - The ExpressionClassBuilder for the class being built

mb - The method the expression will go into

Throws:

StandardException - Thrown on error