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

java.lang.Object
  org.apache.derby.impl.sql.compile.QueryTreeNode
      org.apache.derby.impl.sql.compile.ValueNode
          org.apache.derby.impl.sql.compile.VirtualColumnNode

All Implemented Interfaces:

Visitable

public class VirtualColumnNode

extends ValueNode

A VirtualColumnNode represents a virtual column reference to a column in a row returned by an underlying ResultSetNode. The underlying column could be in a base table, view (which could expand into a complex expression), subquery in the FROM clause, temp table, expression result, etc. By the time we get to code generation, all VirtualColumnNodes should stand only for references to columns in a base table within a FromBaseTable.

Author:

Jeff Lichtman

Field Summary

(package private) int	columnId
(package private) boolean	correlated
(package private) ResultColumn	sourceColumn
(package private) ResultSetNode	sourceResultSet

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

clause, dataTypeServices, IN_HAVING_CLAUSE, IN_SELECT_LIST, IN_UNKNOWN_CLAUSE, IN_WHERE_CLAUSE, transformed

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

AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX, beginOffset, endOffset

Constructor Summary

VirtualColumnNode()

Method Summary

void	generateExpression(ExpressionClassBuilder acb, MethodBuilder mb) ColumnNode's are against the current row in the system.
(package private) boolean	getCorrelated() Return whether or not this VCN is a correlated reference.
protected int	getOrderableVariantType() Return the variant type for the underlying expression.
java.lang.String	getSchemaName() Get the name of the schema the ResultColumn's table is in, if any.
ResultColumn	getSourceColumn() Return the ResultColumn that is the source of this VirtualColumnNode.
ResultColumn	getSourceResultColumn() Return the ResultColumn that is the source of this VirtualColumnNode.
ResultSetNode	getSourceResultSet() Return the ResultSetNode that is the source of this VirtualColumnNode.
java.lang.String	getTableName() Get the name of the table the ResultColumn is in, if any.
DataTypeDescriptor	getTypeServices() Get the DataTypeServices from this Node.
void	init(java.lang.Object sourceResultSet, java.lang.Object sourceColumn, java.lang.Object columnId) Initializer for a VirtualColumnNode.
boolean	isCloneable() Return whether or not this expression tree is cloneable.
void	printSubNodes(int depth) Prints the sub-nodes of this object.
(package private) void	setCorrelated() Mark this VCN as a reference to a correlated column.
boolean	updatableByCursor() Return whether or not the ResultColumn is wirtable by a positioned update.

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

bindExpression, bindExpression, categorize, changeToCNF, checkIsBoolean, checkReliability, checkReliability, checkTopPredicatesForEqualsConditions, constantExpression, copyFields, eliminateNots, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getClause, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isConstantExpression, isParameterNode, isRelationalOperator, optimizableEqualityNode, preprocess, putAndsOnTop, remapColumnReferencesToExpressions, selectivity, setClause, setDescriptor, setTransformed, setType, toString, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop

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

accept, bind, convertDefaultNode, debugFlush, debugPrint, executeSchemaName, executeStatementName, formatNodeString, foundString, generate, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContextManager, getCursorInfo, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getNodeFactory, getNodeType, getNullNode, getParameterTypes, getRowEstimate, getSchemaDescriptor, getSchemaDescriptor, getSPSName, getStatementType, getTableDescriptor, getTypeCompiler, init, init, init, init, init, init, init, init, init, init, init, init, isAtomic, isInstanceOf, isSessionSchema, isSessionSchema, makeConstantAction, makeResultDescription, makeTableName, needsSavepoint, nodeHeader, optimize, parseQueryText, printLabel, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setContextManager, setEndOffset, setNodeType, setRefActionInfo, treePrint, treePrint, verifyClassExist

Methods inherited from class java.lang.Object

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

Field Detail

sourceResultSet

ResultSetNode sourceResultSet

sourceColumn

ResultColumn sourceColumn

columnId

int columnId

correlated

boolean correlated

Constructor Detail

VirtualColumnNode

public VirtualColumnNode()

Method Detail

init

public void init(java.lang.Object sourceResultSet,
                 java.lang.Object sourceColumn,
                 java.lang.Object columnId)

Initializer for a VirtualColumnNode.

Overrides:

init in class QueryTreeNode

Parameters:

sourceResultSet - The ResultSetNode where the value is originating

sourceColumn - The ResultColumn where the value is originating

columnId - The columnId within the current Row

printSubNodes

public void printSubNodes(int depth)

Prints the sub-nodes of this object. See QueryTreeNode.java for how tree printing is supposed to work.

Overrides:

printSubNodes in class QueryTreeNode

Parameters:

depth - The depth of this node in the tree

Returns:

Nothing

getSourceResultSet

public ResultSetNode getSourceResultSet()

Return the ResultSetNode that is the source of this VirtualColumnNode.

Returns:

ResultSetNode

getSourceColumn

public ResultColumn getSourceColumn()

Return the ResultColumn that is the source of this VirtualColumnNode.

Returns:

ResultSetNode

getTableName

public java.lang.String getTableName()

Get the name of the table the ResultColumn is in, if any. This will be null if the user did not supply a name (for example, select a from t). The method will return B for this example, select b.a from t as b The method will return T for this example, select t.a from t

Overrides:

getTableName in class ValueNode

Returns:

A String containing the name of the table the Column is in. If the column is not in a table (i.e. is a derived column), it returns NULL.

getSchemaName

public java.lang.String getSchemaName()
                               throws StandardException

Get the name of the schema the ResultColumn's table is in, if any. The return value will be null if the user did not supply a schema name (for example, select t.a from t). Another example for null return value (for example, select b.a from t as b). But for following query select app.t.a from t, this will return APP

Overrides:

getSchemaName in class ValueNode

Returns:

A String containing the name of the schema for the Column's table. If the column is not in a schema (i.e. derived column), it returns NULL.

Throws:

StandardException

updatableByCursor

public boolean updatableByCursor()

Return whether or not the ResultColumn is wirtable by a positioned update.

Overrides:

updatableByCursor in class ValueNode

Returns:

TRUE, if the column is a base column of a table and is writable by a positioned update.

getSourceResultColumn

public ResultColumn getSourceResultColumn()

Return the ResultColumn that is the source of this VirtualColumnNode.

Overrides:

getSourceResultColumn in class ValueNode

Returns:

ResultSetNode

setCorrelated

void setCorrelated()

Mark this VCN as a reference to a correlated column. (It's source resultSet is an outer ResultSet.

Returns:

Nothing.

getCorrelated

boolean getCorrelated()

Return whether or not this VCN is a correlated reference.

Returns:

Whether or not this VCN is a correlated reference.

isCloneable

public boolean isCloneable()

Return whether or not this expression tree is cloneable.

Overrides:

isCloneable in class ValueNode

Returns:

boolean Whether or not this expression tree is cloneable.

generateExpression

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

ColumnNode's are against the current row in the system. This lets us generate a faster get that simply returns the column from the current row, rather than getting the value out and returning that, only to have the caller (in the situations needed) stuffing it back into a new column holder object. We will assume the general generate() path is for getting the value out, and use generateColumn() when we want to keep the column wrapped.

Overrides:

generateExpression in class ValueNode

Parameters:

mb - The method the expression will go into

Throws:

StandardException - Thrown on error

getOrderableVariantType

protected int getOrderableVariantType()
                               throws StandardException

Return the variant type for the underlying expression. The variant type can be: VARIANT - variant within a scan (method calls and non-static field access) SCAN_INVARIANT - invariant within a scan (column references from outer tables) QUERY_INVARIANT - invariant within the life of a query (constant expressions)

Overrides:

getOrderableVariantType in class ValueNode

Returns:

The variant type for the underlying expression.

Throws:

StandardException - thrown on error

getTypeServices

public DataTypeDescriptor getTypeServices()

Get the DataTypeServices from this Node.

Overrides:

getTypeServices in class ValueNode

Returns:

The DataTypeServices from this Node. This may be null if the node isn't bound yet.