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

java.lang.Object
  extended by org.apache.derby.impl.sql.compile.QueryTreeNode
      extended by org.apache.derby.impl.sql.compile.ValueNode
          extended by org.apache.derby.impl.sql.compile.ConstantNode
              extended by org.apache.derby.impl.sql.compile.UserTypeConstantNode
All Implemented Interfaces:
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
(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, isPrivilegeCollectionRequired
 
Constructor Summary
UserTypeConstantNode()
           
 
Method Summary
(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, 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, getRowEstimate, 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:

- OR -

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

Built on Thu 2010-12-23 20:49:13+0000, from revision ???

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