org.apache.datasketches.hive.hll

Class DataToSketchUDAF

java.lang.Object

org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver

org.apache.datasketches.hive.hll.DataToSketchUDAF

All Implemented Interfaces:

org.apache.hadoop.hive.ql.udf.generic.GenericUDAFResolver, org.apache.hadoop.hive.ql.udf.generic.GenericUDAFResolver2

public class DataToSketchUDAF
extends org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver

Hive UDAF to create an HllSketch from raw data.

Note Strings as raw data values are encoded as a UTF-16 VARCHAR prior to being submitted to the sketch. If the user requires a different encoding for cross-platform compatibility, it is recommended that these values be encoded prior to being submitted and then typed as a BINARY byte[].

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DataToSketchUDAF.DataToSketchEvaluator

Constructor Summary

Constructors

Constructor and Description
DataToSketchUDAF()

Method Summary

Modifier and Type	Method and Description
org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator	getEvaluator(org.apache.hadoop.hive.ql.udf.generic.GenericUDAFParameterInfo info) Performs argument number and type validation.

Methods inherited from class org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver

getEvaluator

Methods inherited from class java.lang.Object

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

Constructor Detail

DataToSketchUDAF

public DataToSketchUDAF()

Method Detail

getEvaluator

public org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator getEvaluator(org.apache.hadoop.hive.ql.udf.generic.GenericUDAFParameterInfo info)
                                                                        throws org.apache.hadoop.hive.ql.parse.SemanticException

Performs argument number and type validation. DataToSketch expects to receive between one and three arguments.

• The first (required) is the value to add to the sketch and must be a primitive.
• The second (optional) is the lgK from 4 to 21 (default 12). This must be an integral value and must be constant.
• The third (optional) is the target HLL type and must be a string 'HLL_4', 'HLL_6' or 'HLL_8' (default 'HLL_4').

Specified by:

getEvaluator in interface org.apache.hadoop.hive.ql.udf.generic.GenericUDAFResolver2

Overrides:

getEvaluator in class org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver

Parameters:

info - Parameter info to validate

Returns:

The GenericUDAFEvaluator that should be used to calculate the function.

Throws:

org.apache.hadoop.hive.ql.parse.SemanticException

See Also:

#getEvaluator(org.apache.hadoop.hive.ql.udf.generic.GenericUDAFParameterInfo)