Class SpecialFunctionNode
- java.lang.Object
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- org.apache.derby.impl.sql.compile.QueryTreeNode
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- org.apache.derby.impl.sql.compile.ValueNode
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- org.apache.derby.impl.sql.compile.SpecialFunctionNode
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- All Implemented Interfaces:
Visitable
class SpecialFunctionNode extends ValueNode
SpecialFunctionNode handles system SQL functions. A function value is either obtained by a method call off the LanguageConnectionContext or Activation. LanguageConnectionContext functions are state related to the connection. Activation functions are those related to the statement execution. Each SQL function takes no arguments and returns a SQLvalue.Functions supported:
- USER
- CURRENT_USER
- CURRENT_ROLE
- SESSION_USER
- SYSTEM_USER
- CURRENT SCHEMA
- CURRENT ISOLATION
- IDENTITY_VAL_LOCAL
This node is used rather than some use of MethodCallNode for runtime performance. MethodCallNode does not provide a fast access to the current language connection or activation, since it is geared towards user defined routines.
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Field Summary
Fields Modifier and Type Field Description (package private) static int
K_CURRENT_ISOLATION
(package private) static int
K_CURRENT_ROLE
(package private) static int
K_CURRENT_SCHEMA
(package private) static int
K_CURRENT_USER
(package private) static int
K_IDENTITY_VAL
(package private) static int
K_SESSION_USER
(package private) static int
K_SYSTEM_USER
(package private) static int
K_USER
(package private) int
kind
This class is used to hold logically different objects for space efficiency.private java.lang.String
methodName
Java method nameprivate java.lang.String
methodType
Return type of Java method.(package private) java.lang.String
sqlName
Name of SQL function-
Fields inherited from class org.apache.derby.impl.sql.compile.ValueNode
transformed
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Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_CYCLE, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX
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Constructor Summary
Constructors Constructor Description SpecialFunctionNode(int kind, ContextManager cm)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description (package private) ValueNode
bindExpression(FromList fromList, SubqueryList subqueryList, java.util.List<AggregateNode> aggregates)
Binding this special function means setting the result DataTypeServices.(package private) void
generateExpression(ExpressionClassBuilder acb, MethodBuilder mb)
Generate an expression that returns a DataValueDescriptor and calls a method off the language connection or the activation.protected int
getOrderableVariantType()
Return the variant type for the underlying expression.(package private) boolean
isEquivalent(ValueNode o)
Tests if this node is equivalent to the specified ValueNode.(package private) boolean
isSameNodeKind(ValueNode o)
Some node classes represent several logical node types (to reduce footprint), which we call kinds.java.lang.String
toString()
Convert this object to a String.-
Methods inherited from class org.apache.derby.impl.sql.compile.ValueNode
bindExpression, categorize, changeToCNF, checkIsBoolean, checkTopPredicatesForEqualsConditions, constantExpression, copyFields, eliminateNots, evaluateConstantExpressions, genEqualsFalseTree, generate, genIsNullTree, genSQLJavaSQLTree, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isConstantExpression, isInListProbeNode, isParameterNode, isRelationalOperator, optimizableEqualityNode, preprocess, putAndsOnTop, remapColumnReferencesToExpressions, requiresTypeFromContext, selectivity, setCollationInfo, setCollationInfo, setCollationUsingCompilationSchema, setCollationUsingCompilationSchema, setNullability, setTransformed, setType, setType, setType, updatableByCursor, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop
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Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
accept, acceptChildren, addTag, addUDTUsagePriv, addUDTUsagePriv, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, bindUserType, checkReliability, checkReliability, convertDefaultNode, copyTagsFrom, createTypeDependency, debugFlush, debugPrint, disablePrivilegeCollection, formatNodeString, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContext, getContextManager, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getLongProperty, getNullNode, getOffsetOrderedNodes, getOptimizerFactory, getOptimizerTracer, getParameterTypes, getSchemaDescriptor, getSchemaDescriptor, getStatementType, getTableDescriptor, getTypeCompiler, getUDTDesc, isAtomic, isPrivilegeCollectionRequired, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, makeTableName, nodeHeader, optimizerTracingIsOn, orReliability, parseSearchCondition, parseStatement, printLabel, printSubNodes, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setEndOffset, setRefActionInfo, stackPrint, taggedWith, treePrint, treePrint, verifyClassExist
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Field Detail
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sqlName
java.lang.String sqlName
Name of SQL function
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K_IDENTITY_VAL
static final int K_IDENTITY_VAL
- See Also:
- Constant Field Values
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K_CURRENT_ISOLATION
static final int K_CURRENT_ISOLATION
- See Also:
- Constant Field Values
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K_CURRENT_SCHEMA
static final int K_CURRENT_SCHEMA
- See Also:
- Constant Field Values
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K_USER
static final int K_USER
- See Also:
- Constant Field Values
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K_CURRENT_USER
static final int K_CURRENT_USER
- See Also:
- Constant Field Values
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K_SESSION_USER
static final int K_SESSION_USER
- See Also:
- Constant Field Values
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K_SYSTEM_USER
static final int K_SYSTEM_USER
- See Also:
- Constant Field Values
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K_CURRENT_ROLE
static final int K_CURRENT_ROLE
- See Also:
- Constant Field Values
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kind
final int kind
This class is used to hold logically different objects for space efficiency.kind
represents the logical object type. See alsoValueNode.isSameNodeKind(org.apache.derby.impl.sql.compile.ValueNode)
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methodName
private java.lang.String methodName
Java method name
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methodType
private java.lang.String methodType
Return type of Java method.
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Constructor Detail
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SpecialFunctionNode
SpecialFunctionNode(int kind, ContextManager cm)
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Method Detail
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bindExpression
ValueNode bindExpression(FromList fromList, SubqueryList subqueryList, java.util.List<AggregateNode> aggregates) throws StandardException
Binding this special function means setting the result DataTypeServices. In this case, the result type is based on the operation requested.- Overrides:
bindExpression
in classValueNode
- Parameters:
fromList
- The FROM list for the statement. This parameter is not used in this case.subqueryList
- The subquery list being built as we find SubqueryNodes. Not used in this case.aggregates
- The aggregate list being built as we find AggregateNodes. Not used in this case.- Returns:
- The new top of the expression tree.
- Throws:
StandardException
- Thrown on error
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getOrderableVariantType
protected int getOrderableVariantType()
Return the variant type for the underlying expression. All supported special functions are QUERY_INVARIANT- Overrides:
getOrderableVariantType
in classValueNode
- Returns:
- The variant type for the underlying expression.
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generateExpression
void generateExpression(ExpressionClassBuilder acb, MethodBuilder mb) throws StandardException
Generate an expression that returns a DataValueDescriptor and calls a method off the language connection or the activation.- Overrides:
generateExpression
in classValueNode
- Parameters:
acb
- The ExpressionClassBuilder for the class being builtmb
- The method the code to place the code- Throws:
StandardException
- Thrown on error
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toString
public java.lang.String toString()
Description copied from class:ValueNode
Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.
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isSameNodeKind
boolean isSameNodeKind(ValueNode o)
Description copied from class:ValueNode
Some node classes represent several logical node types (to reduce footprint), which we call kinds. This means that implementations ofValueNode.isEquivalent(org.apache.derby.impl.sql.compile.ValueNode)
cannot always just useinstanceof
to check if the other node represents the same kind. Hence this method needs to be overridden by all node classes that represent several kinds. This default implementation does not look at kinds. It is only called from implementations ofisEquivalent
.- Overrides:
isSameNodeKind
in classValueNode
- Parameters:
o
- The other value node whose kind we want to compare with.- Returns:
true
ifthis
ando
represent the same logical node type, i.e. kind.
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isEquivalent
boolean isEquivalent(ValueNode o)
Description copied from class:ValueNode
Tests if this node is equivalent to the specified ValueNode. Two ValueNodes are considered equivalent if they will evaluate to the same value during query execution.This method provides basic expression matching facility for the derived class of ValueNode and it is used by the language layer to compare the node structural form of the two expressions for equivalence at bind phase.
Note that it is not comparing the actual row values at runtime to produce a result; hence, when comparing SQL NULLs, they are considered to be equivalent and not unknown.
One usage case of this method in this context is to compare the select column expression against the group by expression to check if they are equivalent. e.g.:
SELECT c1+c2 FROM t1 GROUP BY c1+c2
In general, node equivalence is determined by the derived class of ValueNode. But they generally abide to the rules below:
- The two ValueNodes must be of the same node type to be considered equivalent. e.g.: CastNode vs. CastNode - equivalent (if their args also match), ColumnReference vs CastNode - not equivalent.
- If node P contains other ValueNode(s) and so on, those node(s) must also be of the same node type to be considered equivalent.
- If node P takes a parameter list, then the number of arguments and its arguments for the two nodes must also match to be considered equivalent. e.g.: CAST(c1 as INTEGER) vs CAST(c1 as SMALLINT), they are not equivalent.
- When comparing SQL NULLs in this context, they are considered to be equivalent.
- If this does not apply or it is determined that the two nodes are not equivalent then the derived class of this method should return false; otherwise, return true.
- Specified by:
isEquivalent
in classValueNode
- Parameters:
o
- the node to compare this ValueNode against.- Returns:
true
if the two nodes are equivalent,false
otherwise.
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