com.heitaox.sql.executor.core.function.udaf

类 UDAF<I,U>

java.lang.Object

com.heitaox.sql.executor.core.function.udaf.UDAF<I,U>

类型参数:

I - input parameter type

U - output parameter type the abstract class of the UDAF function, all aggregate functions must inherit this class and implement all the abstract methods in the class.

直接已知子类:

AVG, COUNT, MAX, MIN, SUM

public abstract class UDAF<I,U>
extends Object

字段概要

字段

限定符和类型	字段和说明
static String	AGGREGATE_METHOD_NAME
static String	COMPUTE_RESULT_METHOD_NAME
static String	INIT_MATHOD_NAME

构造器概要

构造器

构造器和说明
UDAF()

方法概要

限定符和类型	方法和说明
abstract U	aggregate(I input, U aggre) Aggregate the input parameters according to a certain logic and the results after the last aggregation
abstract U	computeResult(U aggre) Calculate the final result using the results obtained after the final polymerization
abstract U	getInitData() Initial value of the aggregate function

从类继承的方法 java.lang.Object

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

字段详细资料

INIT_MATHOD_NAME

public static final String INIT_MATHOD_NAME

另请参阅:

常量字段值

AGGREGATE_METHOD_NAME

public static final String AGGREGATE_METHOD_NAME

另请参阅:

常量字段值

COMPUTE_RESULT_METHOD_NAME

public static final String COMPUTE_RESULT_METHOD_NAME

另请参阅:

常量字段值

构造器详细资料

UDAF

public UDAF()

方法详细资料

getInitData

public abstract U getInitData()

Initial value of the aggregate function

返回:

Initial value

aggregate

public abstract U aggregate(I input,
                            U aggre)

Aggregate the input parameters according to a certain logic and the results after the last aggregation

参数:

input - input parameter

aggre - Results after the last aggregation

返回:

Results after this aggregation

computeResult

public abstract U computeResult(U aggre)

Calculate the final result using the results obtained after the final polymerization

参数:

aggre - Result after final polymerization

返回:

final result