org.h2.expression.aggregate

Class Aggregate

java.lang.Object

org.h2.expression.Expression

org.h2.expression.analysis.DataAnalysisOperation

org.h2.expression.aggregate.AbstractAggregate

org.h2.expression.aggregate.Aggregate

All Implemented Interfaces:

ExpressionWithFlags

public class Aggregate
extends AbstractAggregate
implements ExpressionWithFlags

Implements the integrated aggregate functions, such as COUNT, MAX, SUM.

Field Summary

Fields inherited from class org.h2.expression.aggregate.AbstractAggregate

args, distinct, filterCondition, type

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
Aggregate(AggregateType aggregateType, Expression[] args, Select select, boolean distinct) Create a new aggregate object.

Method Summary

Methods

Modifier and Type	Method and Description
protected java.lang.Object	createAggregateData() Create aggregate data object specific to the subclass.
Value	getAggregatedValue(Session session, java.lang.Object aggregateData) Returns aggregated value.
AggregateType	getAggregateType() Returns the type of this aggregate.
static AggregateType	getAggregateType(java.lang.String name) Get the aggregate type for this name, or -1 if no aggregate has been found.
int	getCost() Estimate the cost to process the expression.
int	getFlags() Returns the flags.
protected int	getNumExpressions() Returns the number of expressions, excluding OVER clause.
java.lang.StringBuilder	getSQL(java.lang.StringBuilder builder, boolean alwaysQuote) Appends the SQL statement of this expression to the specified builder.
Value	getValue(Session session) Return the resulting value for the current row.
boolean	isEverything(ExpressionVisitor visitor) Check if this expression and all sub-expressions can fulfill a criteria.
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	setFlags(int flags) Set the flags for this expression.
void	setOrderByList(java.util.ArrayList<SelectOrderBy> orderByList) Set the order for ARRAY_AGG() or GROUP_CONCAT() aggregate.
protected void	updateAggregate(Session session, java.lang.Object aggregateData) Updates an aggregate value.
protected void	updateFromExpressions(Session session, java.lang.Object aggregateData, Value[] array) Updates the provided aggregate data from the remembered expressions.
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.aggregate.AbstractAggregate

appendTailConditions, getOrderedResultLoop, getType, isAggregate, setFilterCondition, updateAggregate

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

createOrder, getGroupData, getOverOrderBySort, getWindowData, 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, isNullConstant, isValueSet, toString, writeExpressions, writeExpressions

Methods inherited from class java.lang.Object

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

Constructor Detail

Aggregate

public Aggregate(AggregateType aggregateType,
         Expression[] args,
         Select select,
         boolean distinct)

Create a new aggregate object.

Parameters:

aggregateType - the aggregate type

args - the aggregated expressions

select - the select statement

distinct - if distinct is used

Method Detail

getAggregateType

public static AggregateType getAggregateType(java.lang.String name)

Get the aggregate type for this name, or -1 if no aggregate has been found.

Parameters:

name - the aggregate function name

Returns:

null if no aggregate function has been found, or the aggregate type

setOrderByList

public void setOrderByList(java.util.ArrayList<SelectOrderBy> orderByList)

Set the order for ARRAY_AGG() or GROUP_CONCAT() aggregate.

Parameters:

orderByList - the order by list

getAggregateType

public AggregateType getAggregateType()

Returns the type of this aggregate.

Returns:

the type of this aggregate

setFlags

public void setFlags(int flags)

Description copied from interface: ExpressionWithFlags

Set the flags for this expression.

Specified by:

setFlags in interface ExpressionWithFlags

Parameters:

flags - the flags to set

getFlags

public int getFlags()

Description copied from interface: ExpressionWithFlags

Returns the flags.

Specified by:

getFlags in interface ExpressionWithFlags

Returns:

the flags

updateAggregate

protected void updateAggregate(Session session,
                   java.lang.Object aggregateData)

Description copied from class: AbstractAggregate

Updates an aggregate value.

Specified by:

updateAggregate in class AbstractAggregate

Parameters:

session - the session

aggregateData - aggregate data

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 AbstractAggregate

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

updateFromExpressions

protected void updateFromExpressions(Session session,
                         java.lang.Object aggregateData,
                         Value[] array)

Description copied from class: AbstractAggregate

Updates the provided aggregate data from the remembered expressions.

Specified by:

updateFromExpressions in class AbstractAggregate

Parameters:

session - the session

aggregateData - aggregate data

array - 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.

getValue

public Value getValue(Session session)

Description copied from class: Expression

Return the resulting value for the current row.

Overrides:

getValue in class DataAnalysisOperation

Parameters:

session - the session

Returns:

the result

getAggregatedValue

public 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 AbstractAggregate

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 AbstractAggregate

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 AbstractAggregate

Parameters:

tableFilter - the table filter

b - true if the table filter can return value

getSQL

public java.lang.StringBuilder getSQL(java.lang.StringBuilder builder,
                             boolean alwaysQuote)

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

alwaysQuote - quote all identifiers

Returns:

the specified string builder

isEverything

public boolean isEverything(ExpressionVisitor visitor)

Description copied from class: Expression

Check if this expression and all sub-expressions can fulfill a criteria. If any part returns false, the result is false.

Overrides:

isEverything in class DataAnalysisOperation

Parameters:

visitor - the visitor

Returns:

if the criteria can be fulfilled

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