org.apache.flink.table.functions.hive

Class HiveDeclarativeAggregateFunction

java.lang.Object

org.apache.flink.table.functions.UserDefinedFunction

org.apache.flink.table.functions.DeclarativeAggregateFunction

org.apache.flink.table.functions.hive.HiveDeclarativeAggregateFunction

All Implemented Interfaces:

Serializable, FunctionDefinition

Direct Known Subclasses:

HiveAverageAggFunction, HiveCountAggFunction, HiveMaxAggFunction, HiveMinAggFunction, HiveSumAggFunction

@Internal
public abstract class HiveDeclarativeAggregateFunction
extends DeclarativeAggregateFunction

API for hive aggregation functions that are expressed in terms of expressions.

Compared to DeclarativeAggregateFunction, this API provides extra setArguments(org.apache.flink.table.types.inference.CallContext) method that is used to set input arguments information before call other methods. We need this API because the aggBuffer and result type of some hive aggregate functions such as sum is decided by the input type, this can be achieved by implements setArguments(org.apache.flink.table.types.inference.CallContext) method correctly.

Moreover, if the hive aggregate function implements this API, planner will use the hash aggregate strategy instead of sort aggregation that performance will be better.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	MAX_SCALE

Constructor Summary

Constructors

Constructor and Description
HiveDeclarativeAggregateFunction()

Method Summary

Modifier and Type	Method and Description
protected UnresolvedCallExpression	adjustedPlus(DataType dataType, Expression arg1, Expression arg2)
protected void	checkArgumentNum(List<DataType> arguments)
protected void	checkMinMaxArgumentType(LogicalType logicalType, String functionName)
FunctionKind	getKind() Returns the kind of function this definition describes.
TypeInference	getTypeInference(DataTypeFactory factory) This method is used to infer result type when generate AggregateCall of calcite.
abstract void	setArguments(CallContext callContext) Set input arguments for the function if need some inputs to infer the aggBuffer type and result type.

Methods inherited from class org.apache.flink.table.functions.DeclarativeAggregateFunction

accumulateExpressions, aggBufferAttributes, getAggBufferTypes, getResultType, getValueExpression, initialValuesExpressions, mergeExpressions, mergeOperand, mergeOperands, operand, operandCount, operands, retractExpressions

Methods inherited from class org.apache.flink.table.functions.UserDefinedFunction

close, functionIdentifier, open, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.flink.table.functions.FunctionDefinition

getRequirements, isDeterministic, supportsConstantFolding

Field Detail

MAX_SCALE

protected static final int MAX_SCALE

See Also:

Constant Field Values

Constructor Detail

HiveDeclarativeAggregateFunction

public HiveDeclarativeAggregateFunction()

Method Detail

setArguments

public abstract void setArguments(CallContext callContext)

Set input arguments for the function if need some inputs to infer the aggBuffer type and result type. Otherwise, just implements it do nothing.

getTypeInference

public TypeInference getTypeInference(DataTypeFactory factory)

This method is used to infer result type when generate AggregateCall of calcite.

Specified by:

getTypeInference in interface FunctionDefinition

Overrides:

getTypeInference in class DeclarativeAggregateFunction

checkArgumentNum

protected void checkArgumentNum(List<DataType> arguments)

checkMinMaxArgumentType

protected void checkMinMaxArgumentType(LogicalType logicalType,
                                       String functionName)

adjustedPlus

protected UnresolvedCallExpression adjustedPlus(DataType dataType,
                                                Expression arg1,
                                                Expression arg2)

getKind

public FunctionKind getKind()

Description copied from interface: FunctionDefinition

Returns the kind of function this definition describes.

Specified by:

getKind in interface FunctionDefinition

Overrides:

getKind in class DeclarativeAggregateFunction