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

java.lang.Object
  org.apache.derby.impl.sql.compile.QueryTreeNode
      org.apache.derby.impl.sql.compile.QueryTreeNodeVector
          org.apache.derby.impl.sql.compile.OrderedColumnList
              org.apache.derby.impl.sql.compile.OrderByList

All Implemented Interfaces:

RequiredRowOrdering, Visitable

public class OrderByList

extends OrderedColumnList

implements RequiredRowOrdering

An OrderByList is an ordered list of columns in the ORDER BY clause. That is, the order of columns in this list is significant - the first column in the list is the most significant in the ordering, and the last column in the list is the least significant.

Author:

ames

Field Summary

private boolean	allAscending
private boolean	alwaysSort
private ColumnOrdering[]	columnOrdering
private int	estimatedRowSize
private java.lang.Object[]	resultRow
private ResultSetNode	resultToSort
private SortCostController	scc
private boolean	sortNeeded

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

AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX, beginOffset, endOffset

Fields inherited from interface org.apache.derby.iapi.sql.compile.RequiredRowOrdering

ELIMINATE_DUPS, NOTHING_REQUIRED, SORT_REQUIRED

Constructor Summary

OrderByList()

Method Summary

void	addOrderByColumn(OrderByColumn column) Add a column to the list
(package private) boolean	allAscending() Are all columns in the list ascending.
void	bindOrderByColumns(ResultSetNode target) Bind the update columns by their names to the target resultset of the cursor specification.
void	estimateCost(double estimatedInputRows, RowOrdering rowOrdering, CostEstimate resultCost) Estimate the cost of doing a sort for this row ordering, given the number of rows to be sorted.
void	generate(ActivationClassBuilder acb, MethodBuilder mb, ResultSetNode child) generate the sort result set operating over the source expression.
OrderByColumn	getOrderByColumn(int position) Get a column from the list
boolean	getSortNeeded() Get whether or not a sort is needed.
(package private) boolean	isInOrderPrefix(ResultColumnList sourceRCL) Is this order by list an in order prefix of the specified RCL.
void	printSubNodes(int depth) Print the list.
void	pullUpOrderByColumns(ResultSetNode target) Pull up Order By columns by their names to the target resultset of the cursor specification.
(package private) void	remapColumnReferencesToExpressions() Remap all ColumnReferences in this tree to be clones of the underlying expression.
(package private) void	removeConstantColumns(PredicateList whereClause) Remove any constant columns from this order by list.
(package private) void	removeDupColumns() Remove any duplicate columns from this order by list.
(package private) ResultColumnList	reorderRCL(ResultColumnList resultColumns) Build a new RCL with the same RCs as the passed in RCL but in an order that matches the ordering columns.
(package private) void	resetToSourceRCs() Order by columns now point to the PRN above the node of interest.
void	sortNeeded() Indicate that a sort is necessary to fulfill this required ordering.
void	sortNotNeeded() Indicate that a sort is *NOT* necessary to fulfill this required ordering.
int	sortRequired(RowOrdering rowOrdering) Tell whether sorting is required for this RequiredRowOrdering, given a RowOrdering.
int	sortRequired(RowOrdering rowOrdering, JBitSet tableMap) Tell whether sorting is required for this RequiredRowOrdering, given a RowOrdering representing a partial join order, and a bit map telling what tables are represented in the join order.

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

accept, addElement, destructiveAppend, elementAt, getColumnOrdering, indexOf, insertElementAt, nondestructiveAppend, remove, removeAllElements, removeElement, removeElementAt, setElementAt, size, toString

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

bind, convertDefaultNode, debugFlush, debugPrint, executeSchemaName, executeStatementName, formatNodeString, foundString, generate, 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, 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

allAscending

private boolean allAscending

alwaysSort

private boolean alwaysSort

resultToSort

private ResultSetNode resultToSort

scc

private SortCostController scc

resultRow

private java.lang.Object[] resultRow

columnOrdering

private ColumnOrdering[] columnOrdering

estimatedRowSize

private int estimatedRowSize

sortNeeded

private boolean sortNeeded

Constructor Detail

OrderByList

public OrderByList()

Method Detail

addOrderByColumn

public void addOrderByColumn(OrderByColumn column)

Add a column to the list

Parameters:

column - The column to add to the list

allAscending

boolean allAscending()

Are all columns in the list ascending.

Returns:

Whether or not all columns in the list ascending.

getOrderByColumn

public OrderByColumn getOrderByColumn(int position)

Get a column from the list

Parameters:

position - The column to get from the list

printSubNodes

public void printSubNodes(int depth)

Print the list.

Overrides:

printSubNodes in class QueryTreeNode

Parameters:

depth - The depth at which to indent the sub-nodes

Returns:

Nothing

bindOrderByColumns

public void bindOrderByColumns(ResultSetNode target)
                        throws StandardException

Bind the update columns by their names to the target resultset of the cursor specification.

Parameters:

target - The underlying result set

Throws:

StandardException - Thrown on error

pullUpOrderByColumns

public void pullUpOrderByColumns(ResultSetNode target)
                          throws StandardException

Pull up Order By columns by their names to the target resultset of the cursor specification.

Parameters:

target - The underlying result set

Throws:

StandardException

isInOrderPrefix

boolean isInOrderPrefix(ResultColumnList sourceRCL)

Is this order by list an in order prefix of the specified RCL. This is useful when deciding if an order by list can be eliminated due to a sort from an underlying distinct or union.

Parameters:

sourceRCL - The source RCL.

Returns:

Whether or not this order by list an in order prefix of the specified RCL.

resetToSourceRCs

void resetToSourceRCs()

Order by columns now point to the PRN above the node of interest. We need them to point to the RCL under that one. This is useful when combining sorts where we need to reorder the sorting columns.

Returns:

Nothing.

reorderRCL

ResultColumnList reorderRCL(ResultColumnList resultColumns)
                      throws StandardException

Build a new RCL with the same RCs as the passed in RCL but in an order that matches the ordering columns.

Parameters:

resultColumns - The RCL to reorder.

Throws:

StandardException - Thrown on error

removeConstantColumns

void removeConstantColumns(PredicateList whereClause)

Remove any constant columns from this order by list. Constant columns are ones where all of the column references are equal to constant expressions according to the given predicate list.

removeDupColumns

void removeDupColumns()

Remove any duplicate columns from this order by list. For example, one may "ORDER BY 1, 1, 2" can be reduced to "ORDER BY 1, 2". Beetle 5401.

generate

public void generate(ActivationClassBuilder acb,
                     MethodBuilder mb,
                     ResultSetNode child)
              throws StandardException

generate the sort result set operating over the source expression.

Parameters:

acb - the tool for building the class

mb - the method the generated code is to go into

Throws:

StandardException - thrown on failure

sortRequired

public int sortRequired(RowOrdering rowOrdering)
                 throws StandardException

Description copied from interface: RequiredRowOrdering

Tell whether sorting is required for this RequiredRowOrdering, given a RowOrdering.

Specified by:

sortRequired in interface RequiredRowOrdering

Parameters:

rowOrdering - The order of rows in question

Returns:

SORT_REQUIRED if sorting is required, ELIMINATE_DUPS if no sorting is required but duplicates must be eliminated (i.e. the rows are in the right order but there may be duplicates), NOTHING_REQUIRED is no operation is required

Throws:

StandardException - Thrown on error

See Also:

RequiredRowOrdering.sortRequired(org.apache.derby.iapi.sql.compile.RowOrdering)

sortRequired

public int sortRequired(RowOrdering rowOrdering,
                        JBitSet tableMap)
                 throws StandardException

Description copied from interface: RequiredRowOrdering

Tell whether sorting is required for this RequiredRowOrdering, given a RowOrdering representing a partial join order, and a bit map telling what tables are represented in the join order. This is useful for reducing the number of cases the optimizer has to consider.

Specified by:

sortRequired in interface RequiredRowOrdering

Parameters:

rowOrdering - The order of rows in the partial join order

tableMap - A bit map of the tables in the partial join order

Returns:

SORT_REQUIRED if sorting is required, ELIMINATE_DUPS if no sorting is required by duplicates must be eliminated (i.e. the rows are in the right order but there may be duplicates), NOTHING_REQUIRED is no operation is required

Throws:

StandardException - Thrown on error

See Also:

RequiredRowOrdering.sortRequired(org.apache.derby.iapi.sql.compile.RowOrdering)

estimateCost

public void estimateCost(double estimatedInputRows,
                         RowOrdering rowOrdering,
                         CostEstimate resultCost)
                  throws StandardException

Description copied from interface: RequiredRowOrdering

Estimate the cost of doing a sort for this row ordering, given the number of rows to be sorted. This does not take into account whether the sort is really needed. It also estimates the number of result rows.

Specified by:

estimateCost in interface RequiredRowOrdering

Parameters:

estimatedInputRows - The estimated number of rows to sort

rowOrdering - The ordering of the input rows

resultCost - A place to store the resulting cost

Throws:

StandardException - Thrown on error

See Also:

RequiredRowOrdering.estimateCost(double, org.apache.derby.iapi.sql.compile.RowOrdering, org.apache.derby.iapi.sql.compile.CostEstimate)

sortNeeded

public void sortNeeded()

Description copied from interface: RequiredRowOrdering

Indicate that a sort is necessary to fulfill this required ordering. This method may be called many times during a single optimization.

Specified by:

sortNeeded in interface RequiredRowOrdering

See Also:

RequiredRowOrdering.sortNeeded()

sortNotNeeded

public void sortNotNeeded()

Description copied from interface: RequiredRowOrdering

Indicate that a sort is *NOT* necessary to fulfill this required ordering. This method may be called many times during a single optimization.

Specified by:

sortNotNeeded in interface RequiredRowOrdering

See Also:

RequiredRowOrdering.sortNotNeeded()

remapColumnReferencesToExpressions

void remapColumnReferencesToExpressions()
                                  throws StandardException

Remap all ColumnReferences in this tree to be clones of the underlying expression.

Returns:

Nothing.

Throws:

StandardException - Thrown on error

getSortNeeded

public boolean getSortNeeded()

Get whether or not a sort is needed.

Specified by:

getSortNeeded in interface RequiredRowOrdering

Returns:

Whether or not a sort is needed.