org.h2.expression.analysis

Class WindowFunction

java.lang.Object

org.h2.expression.Expression

org.h2.expression.analysis.DataAnalysisOperation

org.h2.expression.analysis.WindowFunction

public class WindowFunction
extends DataAnalysisOperation

A window function.

Field Summary

Fields inherited from class org.h2.expression.analysis.DataAnalysisOperation

over, overOrderBySort, select, STAGE_GROUP, STAGE_RESET, STAGE_WINDOW

Fields inherited from class org.h2.expression.Expression

MAP_IN_AGGREGATE, MAP_IN_WINDOW, MAP_INITIAL

Constructor Summary

Constructors

Constructor and Description
WindowFunction(WindowFunctionType type, Select select, Expression[] args) Creates new instance of a window function.

Method Summary

Methods

Modifier and Type	Method and Description
protected java.lang.Object	createAggregateData() Create aggregate data object specific to the subclass.
protected Value	getAggregatedValue(Session session, java.lang.Object aggregateData) Returns aggregated value.
int	getCost() Estimate the cost to process the expression.
WindowFunctionType	getFunctionType() Returns the type of this function.
static int	getMaxArgumentCount(WindowFunctionType type) Returns maximal number of arguments for the specified type.
static int	getMinArgumentCount(WindowFunctionType type) Returns minimal number of arguments for the specified type.
protected int	getNumExpressions() Returns the number of expressions, excluding OVER clause.
protected void	getOrderedResultLoop(Session session, java.util.HashMap<java.lang.Integer,Value> result, java.util.ArrayList<Value[]> ordered, int rowIdColumn) Returns result of this window function or window aggregate.
java.lang.StringBuilder	getSQL(java.lang.StringBuilder builder) Appends the SQL statement of this expression to the specified builder.
TypeInfo	getType() Returns the data type.
boolean	isAggregate() Checks whether this expression is an aggregate function.
void	mapColumnsAnalysis(ColumnResolver resolver, int level, int innerState) Map the columns of the resolver to expression columns.
Expression	optimize(Session session) Try to optimize the expression.
protected void	rememberExpressions(Session session, Value[] array) Stores current values of expressions into the specified array.
void	setEvaluatable(TableFilter tableFilter, boolean b) Tell the expression columns whether the table filter can return values now.
void	setFromLast(boolean fromLast) Sets FROM FIRST or FROM LAST clause value.
void	setIgnoreNulls(boolean ignoreNulls) Sets RESPECT NULLS or IGNORE NULLS clause value.
protected void	updateAggregate(Session session, SelectGroups groupData, int groupRowId) Update a row of an aggregate.
protected void	updateGroupAggregates(Session session, int stage) Invoked when processing group stage of grouped window queries to update arguments of this aggregate.

Methods inherited from class org.h2.expression.analysis.DataAnalysisOperation

appendTailConditions, createOrder, getGroupData, getOverOrderBySort, getValue, getWindowData, isEverything, mapColumns, setOverCondition, updateAggregate, updateOrderedAggregate

Methods inherited from class org.h2.expression.Expression

addFilterConditions, createIndexConditions, getAlias, getBooleanValue, getColumnName, getExpressionColumns, getExpressionColumns, getExpressionColumns, getNonAliasExpression, getNotIfPossible, getNullable, getSchemaName, getSQL, getSubexpression, getSubexpressionCount, getTableAlias, getTableName, getUnenclosedSQL, isAutoIncrement, isConstant, isGeneratedKey, isValueSet, toString, writeExpressions, writeExpressions

Methods inherited from class java.lang.Object

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

Constructor Detail

WindowFunction

public WindowFunction(WindowFunctionType type,
              Select select,
              Expression[] args)

Creates new instance of a window function.

Parameters:

type - the type

select - the select statement

args - arguments, or null

Method Detail

getMinArgumentCount

public static int getMinArgumentCount(WindowFunctionType type)

Returns minimal number of arguments for the specified type.

Parameters:

type - the type of a window function

Returns:

minimal number of arguments

getMaxArgumentCount

public static int getMaxArgumentCount(WindowFunctionType type)

Returns maximal number of arguments for the specified type.

Parameters:

type - the type of a window function

Returns:

maximal number of arguments

getFunctionType

public WindowFunctionType getFunctionType()

Returns the type of this function.

Returns:

the type of this function

setFromLast

public void setFromLast(boolean fromLast)

Sets FROM FIRST or FROM LAST clause value.

Parameters:

fromLast - whether FROM LAST clause was specified.

setIgnoreNulls

public void setIgnoreNulls(boolean ignoreNulls)

Sets RESPECT NULLS or IGNORE NULLS clause value.

Parameters:

ignoreNulls - whether IGNORE NULLS clause was specified

isAggregate

public boolean isAggregate()

Description copied from class: DataAnalysisOperation

Checks whether this expression is an aggregate function.

Specified by:

isAggregate in class DataAnalysisOperation

Returns:

true if this is an aggregate function (including aggregates with OVER clause), false if this is a window function

updateAggregate

protected void updateAggregate(Session session,
                   SelectGroups groupData,
                   int groupRowId)

Description copied from class: DataAnalysisOperation

Update a row of an aggregate.

Specified by:

updateAggregate in class DataAnalysisOperation

Parameters:

session - the database session

groupData - data for the aggregate group

groupRowId - row id of group

updateGroupAggregates

protected void updateGroupAggregates(Session session,
                         int stage)

Description copied from class: DataAnalysisOperation

Invoked when processing group stage of grouped window queries to update arguments of this aggregate.

Overrides:

updateGroupAggregates in class DataAnalysisOperation

Parameters:

session - the session

stage - select stage

getNumExpressions

protected int getNumExpressions()

Description copied from class: DataAnalysisOperation

Returns the number of expressions, excluding OVER clause.

Specified by:

getNumExpressions in class DataAnalysisOperation

Returns:

the number of expressions

rememberExpressions

protected void rememberExpressions(Session session,
                       Value[] array)

Description copied from class: DataAnalysisOperation

Stores current values of expressions into the specified array.

Specified by:

rememberExpressions in class DataAnalysisOperation

Parameters:

session - the session

array - array to store values of expressions

createAggregateData

protected java.lang.Object createAggregateData()

Description copied from class: DataAnalysisOperation

Create aggregate data object specific to the subclass.

Specified by:

createAggregateData in class DataAnalysisOperation

Returns:

aggregate-specific data object.

getOrderedResultLoop

protected void getOrderedResultLoop(Session session,
                        java.util.HashMap<java.lang.Integer,Value> result,
                        java.util.ArrayList<Value[]> ordered,
                        int rowIdColumn)

Description copied from class: DataAnalysisOperation

Returns result of this window function or window aggregate. This method may not be called on window aggregate without window order clause.

Specified by:

getOrderedResultLoop in class DataAnalysisOperation

Parameters:

session - the session

result - the map to append result to

ordered - ordered data

rowIdColumn - the index of row id value

getAggregatedValue

protected Value getAggregatedValue(Session session,
                       java.lang.Object aggregateData)

Description copied from class: DataAnalysisOperation

Returns aggregated value.

Specified by:

getAggregatedValue in class DataAnalysisOperation

Parameters:

session - the session

aggregateData - the aggregate data

Returns:

aggregated value.

mapColumnsAnalysis

public void mapColumnsAnalysis(ColumnResolver resolver,
                      int level,
                      int innerState)

Description copied from class: DataAnalysisOperation

Map the columns of the resolver to expression columns.

Overrides:

mapColumnsAnalysis in class DataAnalysisOperation

Parameters:

resolver - the column resolver

level - the subquery nesting level

innerState - one of the Expression MAP_IN_* values

optimize

public Expression optimize(Session session)

Description copied from class: Expression

Try to optimize the expression.

Overrides:

optimize in class DataAnalysisOperation

Parameters:

session - the session

Returns:

the optimized expression

setEvaluatable

public void setEvaluatable(TableFilter tableFilter,
                  boolean b)

Description copied from class: Expression

Tell the expression columns whether the table filter can return values now. This is used when optimizing the query.

Overrides:

setEvaluatable in class DataAnalysisOperation

Parameters:

tableFilter - the table filter

b - true if the table filter can return value

getType

public TypeInfo getType()

Description copied from class: Expression

Returns the data type. The data type may not be known before the optimization phase.

Specified by:

getType in class Expression

Returns:

the data type

getSQL

public java.lang.StringBuilder getSQL(java.lang.StringBuilder builder)

Description copied from class: Expression

Appends the SQL statement of this expression to the specified builder. This may not always be the original SQL statement, specially after optimization.

Specified by:

getSQL in class Expression

Parameters:

builder - string builder

Returns:

the specified string builder

getCost

public int getCost()

Description copied from class: Expression

Estimate the cost to process the expression. Used when optimizing the query, to calculate the query plan with the lowest estimated cost.

Specified by:

getCost in class Expression

Returns:

the estimated cost