org.apache.flink.table.planner.functions.aggfunctions

类 LeadLagAggFunction

java.lang.Object

org.apache.flink.table.functions.UserDefinedFunction

org.apache.flink.table.planner.functions.aggfunctions.DeclarativeAggregateFunction

org.apache.flink.table.planner.functions.aggfunctions.LeadLagAggFunction

所有已实现的接口:

Serializable, org.apache.flink.table.functions.FunctionDefinition

直接已知子类:

LeadLagAggFunction.BooleanLeadLagAggFunction, LeadLagAggFunction.ByteLeadLagAggFunction, LeadLagAggFunction.CharLeadLagAggFunction, LeadLagAggFunction.DateLeadLagAggFunction, LeadLagAggFunction.DecimalLeadLagAggFunction, LeadLagAggFunction.DoubleLeadLagAggFunction, LeadLagAggFunction.FloatLeadLagAggFunction, LeadLagAggFunction.IntLeadLagAggFunction, LeadLagAggFunction.LongLeadLagAggFunction, LeadLagAggFunction.ShortLeadLagAggFunction, LeadLagAggFunction.StringLeadLagAggFunction, LeadLagAggFunction.TimeLeadLagAggFunction, LeadLagAggFunction.TimestampLeadLagAggFunction

public abstract class LeadLagAggFunction
extends DeclarativeAggregateFunction

LEAD and LAG aggregate functions return the value of given expression evaluated at given offset. The functions only are used by over window.

LAG(input, offset, default) - Returns the value of `input` at the `offset`th row before the current row in the window. The default value of `offset` is 1 and the default value of `default` is null. If the value of `input` at the `offset`th row is null, null is returned. If there is no such offset row (e.g., when the offset is 1, the first row of the window does not have any previous row), `default` is returned.

LEAD(input, offset, default) - Returns the value of `input` at the `offset`th row after the current row in the window. The default value of `offset` is 1 and the default value of `default` is null. If the value of `input` at the `offset`th row is null, null is returned. If there is no such an offset row (e.g., when the offset is 1, the last row of the window does not have any subsequent row), `default` is returned.

These two aggregate functions are special, and only are used by over window. So here the concrete implementation is closely related to OffsetOverFrame.

另请参阅:

序列化表格

嵌套类概要

嵌套类

限定符和类型	类和说明
static class	LeadLagAggFunction.BooleanLeadLagAggFunction BooleanLeadLagAggFunction.
static class	LeadLagAggFunction.ByteLeadLagAggFunction ByteLeadLagAggFunction.
static class	LeadLagAggFunction.CharLeadLagAggFunction CharLeadLagAggFunction.
static class	LeadLagAggFunction.DateLeadLagAggFunction DateLeadLagAggFunction.
static class	LeadLagAggFunction.DecimalLeadLagAggFunction DecimalLeadLagAggFunction.
static class	LeadLagAggFunction.DoubleLeadLagAggFunction DoubleLeadLagAggFunction.
static class	LeadLagAggFunction.FloatLeadLagAggFunction FloatLeadLagAggFunction.
static class	LeadLagAggFunction.IntLeadLagAggFunction IntLeadLagAggFunction.
static class	LeadLagAggFunction.LongLeadLagAggFunction LongLeadLagAggFunction.
static class	LeadLagAggFunction.ShortLeadLagAggFunction ShortLeadLagAggFunction.
static class	LeadLagAggFunction.StringLeadLagAggFunction StringLeadLagAggFunction.
static class	LeadLagAggFunction.TimeLeadLagAggFunction TimeLeadLagAggFunction.
static class	LeadLagAggFunction.TimestampLeadLagAggFunction TimestampLeadLagAggFunction.

构造器概要

构造器

构造器和说明
LeadLagAggFunction(int operandCount)

方法概要

限定符和类型	方法和说明
org.apache.flink.table.expressions.Expression[]	accumulateExpressions() Expressions for accumulating the mutable aggregation buffer based on an input row.
org.apache.flink.table.expressions.UnresolvedReferenceExpression[]	aggBufferAttributes() All fields of the aggregate buffer.
org.apache.flink.table.types.DataType[]	getAggBufferTypes() All types of the aggregate buffer.
org.apache.flink.table.expressions.Expression	getValueExpression() An expression which returns the final value for this aggregate function.
org.apache.flink.table.expressions.Expression[]	initialValuesExpressions() Expressions for initializing empty aggregation buffers.
org.apache.flink.table.expressions.Expression[]	mergeExpressions() A sequence of expressions for merging two aggregation buffers together.
int	operandCount() How many operands your function will deal with.
org.apache.flink.table.expressions.Expression[]	retractExpressions() Expressions for retracting the mutable aggregation buffer based on an input row.

从类继承的方法 org.apache.flink.table.planner.functions.aggfunctions.DeclarativeAggregateFunction

getKind, getResultType, getTypeInference, mergeOperand, mergeOperands, operand, operands

从类继承的方法 org.apache.flink.table.functions.UserDefinedFunction

close, functionIdentifier, open, toString

从类继承的方法 java.lang.Object

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

从接口继承的方法 org.apache.flink.table.functions.FunctionDefinition

getRequirements, isDeterministic

构造器详细资料

LeadLagAggFunction

public LeadLagAggFunction(int operandCount)

方法详细资料

operandCount

public int operandCount()

从类复制的说明: DeclarativeAggregateFunction

How many operands your function will deal with.

指定者:

operandCount 在类中 DeclarativeAggregateFunction

aggBufferAttributes

public org.apache.flink.table.expressions.UnresolvedReferenceExpression[] aggBufferAttributes()

从类复制的说明: DeclarativeAggregateFunction

All fields of the aggregate buffer.

指定者:

aggBufferAttributes 在类中 DeclarativeAggregateFunction

getAggBufferTypes

public org.apache.flink.table.types.DataType[] getAggBufferTypes()

从类复制的说明: DeclarativeAggregateFunction

All types of the aggregate buffer.

指定者:

getAggBufferTypes 在类中 DeclarativeAggregateFunction

initialValuesExpressions

public org.apache.flink.table.expressions.Expression[] initialValuesExpressions()

从类复制的说明: DeclarativeAggregateFunction

Expressions for initializing empty aggregation buffers.

指定者:

initialValuesExpressions 在类中 DeclarativeAggregateFunction

accumulateExpressions

public org.apache.flink.table.expressions.Expression[] accumulateExpressions()

从类复制的说明: DeclarativeAggregateFunction

Expressions for accumulating the mutable aggregation buffer based on an input row.

指定者:

accumulateExpressions 在类中 DeclarativeAggregateFunction

retractExpressions

public org.apache.flink.table.expressions.Expression[] retractExpressions()

从类复制的说明: DeclarativeAggregateFunction

Expressions for retracting the mutable aggregation buffer based on an input row.

指定者:

retractExpressions 在类中 DeclarativeAggregateFunction

mergeExpressions

public org.apache.flink.table.expressions.Expression[] mergeExpressions()

从类复制的说明: DeclarativeAggregateFunction

A sequence of expressions for merging two aggregation buffers together. When defining these expressions, you can use the syntax attributeName and mergeOperand(attributeName) to refer to the attributes corresponding to each of the buffers being merged.

指定者:

mergeExpressions 在类中 DeclarativeAggregateFunction

getValueExpression

public org.apache.flink.table.expressions.Expression getValueExpression()

从类复制的说明: DeclarativeAggregateFunction

An expression which returns the final value for this aggregate function.

指定者:

getValueExpression 在类中 DeclarativeAggregateFunction