CurrentOfNode (Apache Derby V10.14 Internals)

java.lang.Object
- org.apache.derby.impl.sql.compile.QueryTreeNode
- - org.apache.derby.impl.sql.compile.ResultSetNode
  - - org.apache.derby.impl.sql.compile.FromTable
    - - org.apache.derby.impl.sql.compile.CurrentOfNode

All Implemented Interfaces:

Optimizable, Visitable
```
public final class CurrentOfNode
extends FromTable
```
The CurrentOf operator is used by positioned DELETE and UPDATE to get the current row and location for the target cursor. The bind() operations for positioned DELETE and UPDATE add a column to the select list under the statement for the row location accessible from this node. This node is placed in the from clause of the select generated for the delete or update operation. It acts much like a FromBaseTable, using the information about the target table of the cursor to provide information.

Nested Class Summary
- Nested classes/interfaces inherited from class org.apache.derby.impl.sql.compile.ResultSetNode
  ResultSetNode.QueryExpressionClauses

Field Summary

Fields
Modifier and Type	Field	Description
`private TableName`	`baseTableName`
`private java.lang.String`	`cursorName`
`private FromBaseTable`	`dummyTargetTable`
`private TableName`	`exposedTableName`
`private ExecPreparedStatement`	`preStmt`
`private CostEstimate`	`singleScanCostEstimate`

Fields inherited from class org.apache.derby.impl.sql.compile.FromTable
ADD_PLAN, bestAccessPath, bestCostEstimate, bestSortAvoidancePath, correlationName, corrTableName, currentAccessPath, hashKeyColumns, initialCapacity, level, LOAD_PLAN, loadFactor, maxCapacity, origTableName, REMOVE_PLAN, tableNumber, tableProperties, trulyTheBestAccessPath, userSpecifiedJoinStrategy

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

Constructor Summary

Constructors
Constructor	Description
`CurrentOfNode(java.lang.String correlationName, java.lang.String cursor, java.util.Properties tableProperties, ContextManager cm)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`(package private) void`	`acceptChildren(Visitor v)`	Accept the visitor for all visitable children of this node.
`(package private) void`	`bindExpressions(FromList fromListParam)`	Bind the expressions in this ResultSetNode.
`(package private) ResultSetNode`	`bindNonVTITables(DataDictionary dataDictionary, FromList fromListParam)`	Binding this FromTable means finding the prepared statement for the cursor and creating the result columns (the columns updatable on that cursor).
`CostEstimate`	`estimateCost(OptimizablePredicateList predList, ConglomerateDescriptor cd, CostEstimate outerCost, Optimizer optimizer, RowOrdering rowOrdering)`	Estimate the cost of scanning this Optimizable using the given predicate list with the given conglomerate.
`(package private) void`	`generate(ActivationClassBuilder acb, MethodBuilder mb)`	Generation on a CurrentOfNode creates a scan on the cursor, CurrentOfResultSet.
`(package private) TableName`	`getBaseCursorTargetTableName()`
`(package private) java.lang.String`	`getCursorName()`
`(package private) ExecPreparedStatement`	`getCursorStatement()`	Return the CursorNode associated with a positioned update/delete.
`(package private) java.lang.String`	`getExposedName()`	Get the exposed name for this table, which is the name that can be used to refer to it in the rest of the query.
`(package private) TableName`	`getExposedTableName()`
`(package private) ResultColumn`	`getMatchingColumn(ColumnReference columnReference)`	Try to find a ResultColumn in the table represented by this CurrentOfNode that matches the name in the given ColumnReference.
`(package private) static CurrentOfNode`	`makeForMerge(java.lang.String cursorName, FromBaseTable dummyTargetTable, ContextManager cm)`	Construct a dummy CurrentOfNode just for compiling the DELETE action of a MERGE statement.
`(package private) ResultSetNode`	`optimize(DataDictionary dataDictionary, PredicateList predicateList, double outerRows)`	Optimize this CurrentOfNode.
`(package private) ResultSetNode`	`preprocess(int numTables, GroupByList gbl, FromList fromList)`	Preprocess a CurrentOfNode.
`(package private) void`	`printSubNodes(int depth)`	Prints the sub-nodes of this object.
`java.lang.String`	`toString()`	Convert this object to a String.
`int`	`updateTargetLockMode()`	Get the lock mode for this table as the target of an update statement (a delete or update).

Methods inherited from class org.apache.derby.impl.sql.compile.FromTable
assignCostEstimate, canBeOrdered, columnsAreUpdatable, considerSortAvoidancePath, convertAbsoluteToRelativeColumnPosition, cursorTargetTable, decrementLevel, feasibleJoinStrategy, fillInReferencedTableMap, flatten, forUpdate, getBaseTableName, getBestAccessPath, getBestSortAvoidancePath, getCorrelationName, getCostEstimate, getCurrentAccessPath, getFinalCostEstimate, getFromTableByName, getLevel, getMergeTableID, getName, getNumColumnsReturned, getOrigTableName, getProperties, getResultColumnsForList, getSchemaDescriptor, getSchemaDescriptor, getScratchCostEstimate, getTableDescriptor, getTableName, getTableNumber, getTrulyTheBestAccessPath, getUserSpecifiedJoinStrategy, hashKeyColumns, hasLargeObjectColumns, hasTableNumber, initAccessPaths, initialCapacity, isBaseTable, isCoveringIndex, isFlattenableJoinNode, isJoinColumnForRightOuterJoin, isMaterializable, isOneRowScan, isTargetTable, legalJoinOrder, loadFactor, LOJ_reorderable, markUpdatableByCursor, maxCapacity, memoryUsageOK, modifyAccessPath, needsSpecialRCLBinding, nextAccessPath, optimizeIt, optimizeSubqueries, pullOptPredicates, pushExpressions, pushOptPredicate, rememberAsBest, rememberJoinStrategyAsBest, rememberSortAvoidancePath, resetJoinStrategies, setCostEstimateCost, setHashKeyColumns, setLevel, setMergeTableID, setOrigTableName, setProperties, setTableNumber, startOptimizing, supportsMultipleInstantiations, tellRowOrderingAboutConstantColumns, transformOuterJoins, uniqueJoin, updateBestPlanMap, verifyProperties

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.derby.iapi.sql.compile.Optimizable
getDataDictionary, getOptimizerTracer, getReferencedTableMap, getResultSetNumber, optimizerTracingIsOn

Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
accept, 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, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setEndOffset, setRefActionInfo, stackPrint, taggedWith, treePrint, treePrint, verifyClassExist

Methods inherited from class org.apache.derby.impl.sql.compile.ResultSetNode
addNewPredicate, adjustForSortElimination, adjustForSortElimination, assignResultSetNumber, bindExpressionsWithTables, bindResultColumns, bindResultColumns, bindTargetExpressions, bindUntypedNullsToResultColumns, bindVTITables, changeAccessPath, columnTypesAndLengthsMatch, considerMaterialization, enhanceRCLForInsert, ensurePredicateList, flattenableInFromSubquery, generateNormalizationResultSet, generateResultSet, genProjectRestrict, genProjectRestrict, genProjectRestrictForReordering, getAllResultColumns, getCandidateFinalCostEstimate, getCostEstimate, getCursorTargetTable, getFromList, getNewCostEstimate, getOptimizer, getOptimizerImpl, getRCLForInsert, getReferencedTableMap, getResultColumns, getResultSetNumber, getScratchCostEstimate, isCursorTargetTable, isInsertSource, isNotExists, isOneRowResultSet, isOrderedOn, isPossibleDistinctScan, isStatementResultSet, isUpdatableCursor, LOJgetReferencedTables, makeResultDescription, makeResultDescriptors, markAsCursorTargetTable, markForDistinctScan, markStatementResultSet, modifyAccessPaths, modifyAccessPaths, notCursorTargetTable, notFlattenableJoin, numDistinctAggregates, parseDefault, performMaterialization, printQueryExpressionSuffixClauses, projectResultColumns, pushOffsetFetchFirst, pushOrderByList, pushQueryExpressionSuffix, referencesTarget, rejectParameters, rejectXMLValues, renameGeneratedResultNames, replaceOrForbidDefaults, returnsAtMostOneRow, setCandidateFinalCostEstimate, setCostEstimate, setCursorTargetTable, setInsertSource, setOptimizer, setReferencedTableMap, setResultColumns, setResultSetNumber, setResultToBooleanTrueNode, setScratchCostEstimate, setTableConstructorTypes, subqueryReferencesTarget, verifySelectStarSubquery

Methods inherited from interface org.apache.derby.iapi.sql.compile.Visitable
accept, addTag, taggedWith

- Field Detail
  - cursorName
```
private java.lang.String cursorName
```
  - preStmt
```
private ExecPreparedStatement preStmt
```
  - exposedTableName
```
private TableName exposedTableName
```
  - baseTableName
```
private TableName baseTableName
```
  - singleScanCostEstimate
```
private CostEstimate singleScanCostEstimate
```
  - dummyTargetTable
```
private FromBaseTable dummyTargetTable
```
- Constructor Detail
  - CurrentOfNode
```
CurrentOfNode(java.lang.String correlationName,
              java.lang.String cursor,
              java.util.Properties tableProperties,
              ContextManager cm)
```
- Method Detail
  - makeForMerge
```
static CurrentOfNode makeForMerge(java.lang.String cursorName,
                                  FromBaseTable dummyTargetTable,
                                  ContextManager cm)
```
    Construct a dummy CurrentOfNode just for compiling the DELETE action of a MERGE statement.
  - estimateCost
```
public CostEstimate estimateCost(OptimizablePredicateList predList,
                                 ConglomerateDescriptor cd,
                                 CostEstimate outerCost,
                                 Optimizer optimizer,
                                 RowOrdering rowOrdering)
                          throws StandardException
```
    Description copied from interface: Optimizable
    
    Estimate the cost of scanning this Optimizable using the given predicate list with the given conglomerate. It is assumed that the predicate list has already been classified. This cost estimate is just for one scan, not for the life of the query.
    
    Specified by:
    
    estimateCost in interface Optimizable
    
    Overrides:
    
    estimateCost in class FromTable
    
    Parameters:
    
    predList - The predicate list to optimize against
    
    cd - The conglomerate descriptor to get the cost of
    
    outerCost - The estimated cost of the part of the plan outer to this optimizable.
    
    optimizer - The optimizer to use to help estimate the cost
    
    rowOrdering - The row ordering for all the tables in the join order, including this one.
    
    Returns:
    
    The estimated cost of doing the scan
    
    Throws:
    
    StandardException - Thrown on error
    
    See Also:
    
    Optimizable.estimateCost(org.apache.derby.iapi.sql.compile.OptimizablePredicateList, org.apache.derby.iapi.sql.dictionary.ConglomerateDescriptor, org.apache.derby.iapi.sql.compile.CostEstimate, org.apache.derby.iapi.sql.compile.Optimizer, org.apache.derby.iapi.sql.compile.RowOrdering)
  - bindNonVTITables
```
ResultSetNode bindNonVTITables(DataDictionary dataDictionary,
                               FromList fromListParam)
                        throws StandardException
```
    Binding this FromTable means finding the prepared statement for the cursor and creating the result columns (the columns updatable on that cursor). We expect someone else to verify that the target table of the positioned update or delete is the table under this cursor.
    
    Overrides:
    
    bindNonVTITables in class ResultSetNode
    
    Parameters:
    
    dataDictionary - The DataDictionary to use for binding
    
    fromListParam - FromList to use/append to.
    
    Returns:
    
    ResultSetNode Returns this.
    
    Throws:
    
    StandardException - Thrown on error
  - bindExpressions
```
void bindExpressions(FromList fromListParam)
```
    Bind the expressions in this ResultSetNode. This means binding the sub-expressions, as well as figuring out what the return type is for each expression.
    
    Overrides:
    
    bindExpressions in class ResultSetNode
    
    Parameters:
    
    fromListParam - FromList to use/append to.
  - getMatchingColumn
```
ResultColumn getMatchingColumn(ColumnReference columnReference)
                        throws StandardException
```
    Try to find a ResultColumn in the table represented by this CurrentOfNode that matches the name in the given ColumnReference.
    
    Overrides:
    
    getMatchingColumn in class ResultSetNode
    
    Parameters:
    
    columnReference - The columnReference whose name we're looking for in the given table.
    
    Returns:
    
    A ResultColumn whose expression is the ColumnNode that matches the ColumnReference. Returns null if there is no match.
    
    Throws:
    
    StandardException - Thrown on error
  - preprocess
```
ResultSetNode preprocess(int numTables,
                         GroupByList gbl,
                         FromList fromList)
                  throws StandardException
```
    Preprocess a CurrentOfNode. For a CurrentOfNode, this simply means allocating a referenced table map to avoid downstream NullPointerExceptions. NOTE: There are no bits set in the referenced table map.
    
    Overrides:
    
    preprocess in class ResultSetNode
    
    Parameters:
    
    numTables - The number of tables in the DML Statement
    
    gbl - The group by list, if any
    
    fromList - The from list, if any
    
    Returns:
    
    ResultSetNode at top of preprocessed tree.
    
    Throws:
    
    StandardException - Thrown on error
  - optimize
```
ResultSetNode optimize(DataDictionary dataDictionary,
                       PredicateList predicateList,
                       double outerRows)
                throws StandardException
```
    Optimize this CurrentOfNode. Nothing to do.
    
    Overrides:
    
    optimize in class ResultSetNode
    
    Parameters:
    
    dataDictionary - The DataDictionary to use for optimization
    
    predicateList - The PredicateList to optimize. This should be a single-table predicate with the table the same as the table in this FromTable.
    
    outerRows - The number of outer joining rows
    
    Returns:
    
    ResultSetNode The top of the optimized subtree.
    
    Throws:
    
    StandardException - Thrown on error
  - generate
```
void generate(ActivationClassBuilder acb,
              MethodBuilder mb)
       throws StandardException
```
    Generation on a CurrentOfNode creates a scan on the cursor, CurrentOfResultSet.
    This routine will generate and return a call of the form:
```
                ResultSetFactory.getCurrentOfResultSet(cursorName)
           
```
    Overrides:
    
    generate in class QueryTreeNode
    
    Parameters:
    
    acb - The ActivationClassBuilder for the class being built
    
    mb - The execute() method to be built
    
    Throws:
    
    StandardException - Thrown on error
  - printSubNodes
```
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 ResultSetNode
    
    Parameters:
    
    depth - The depth of this node in the tree
  - toString
```
public java.lang.String toString()
```
    Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.
    
    Overrides:
    
    toString in class FromTable
    
    Returns:
    
    This object as a String
  - getExposedName
```
java.lang.String getExposedName()
```
    Description copied from class: FromTable
    
    Get the exposed name for this table, which is the name that can be used to refer to it in the rest of the query.
    
    Overrides:
    
    getExposedName in class FromTable
    
    Returns:
    
    The exposed name of this table.
  - updateTargetLockMode
```
public int updateTargetLockMode()
```
    Get the lock mode for this table as the target of an update statement (a delete or update). This is implemented only for base tables and CurrentOfNodes.
    
    Overrides:
    
    updateTargetLockMode in class ResultSetNode
    
    Returns:
    
    The lock mode
    
    See Also:
    
    TransactionController
  - getExposedTableName
```
TableName getExposedTableName()
```
  - getBaseCursorTargetTableName
```
TableName getBaseCursorTargetTableName()
```
  - getCursorName
```
java.lang.String getCursorName()
```
  - getCursorStatement
```
ExecPreparedStatement getCursorStatement()
```
    Return the CursorNode associated with a positioned update/delete.
    
    Returns:
    
    CursorNode The associated CursorNode.
  - acceptChildren
```
void acceptChildren(Visitor v)
             throws StandardException
```
    Description copied from class: ResultSetNode
    
    Accept the visitor for all visitable children of this node.
    
    Overrides:
    
    acceptChildren in class FromTable
    
    Parameters:
    
    v - the visitor
    
    Throws:
    
    StandardException - on error

Class CurrentOfNode

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.derby.impl.sql.compile.ResultSetNode

Field Summary

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

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

Constructor Summary

Method Summary

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

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.derby.iapi.sql.compile.Optimizable

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

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

Methods inherited from interface org.apache.derby.iapi.sql.compile.Visitable

Field Detail

cursorName

preStmt

exposedTableName

baseTableName

singleScanCostEstimate

dummyTargetTable

Constructor Detail

CurrentOfNode

Method Detail

makeForMerge

estimateCost

bindNonVTITables

bindExpressions

getMatchingColumn

preprocess

optimize

generate

printSubNodes

toString

getExposedName

updateTargetLockMode

getExposedTableName

getBaseCursorTargetTableName

getCursorName

getCursorStatement

acceptChildren