org.apache.beam.sdk.extensions.zetasketch

Class HllCount.Init.Builder<InputT>

java.lang.Object

org.apache.beam.sdk.extensions.zetasketch.HllCount.Init.Builder<InputT>

Type Parameters:

InputT - element type or value type in KVs of the input PCollection to the PTransform being built

Enclosing class:

HllCount.Init

public static final class HllCount.Init.Builder<InputT>
extends java.lang.Object

Builder for the HllCount.Init combining PTransform.

Call withPrecision(int) to customize the precision parameter of the sketch.

Call globally() or perKey() to finalize the PTransform.

Method Summary

Modifier and Type	Method and Description
Combine.Globally<InputT,byte[]>	globally() Returns a Combine.Globally PTransform that takes an input PCollection<InputT> and returns a PCollection<byte[]> which consists of the HLL++ sketch computed from the elements in the input PCollection.
<K> Combine.PerKey<K,InputT,byte[]>	perKey() Returns a Combine.PerKey PTransform that takes an input PCollection<KV<K, InputT>> and returns a PCollection<KV<K, byte[]>> which consists of the per-key HLL++ sketch computed from the values matching each key in the input PCollection.
HllCount.Init.Builder<InputT>	withPrecision(int precision) Explicitly set the precision parameter used to compute HLL++ sketch.

Methods inherited from class java.lang.Object

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

Method Detail

withPrecision

public HllCount.Init.Builder<InputT> withPrecision(int precision)

Explicitly set the precision parameter used to compute HLL++ sketch.

Valid range is between HllCount.MINIMUM_PRECISION and HllCount.MAXIMUM_PRECISION. If this method is not called, HllCount.DEFAULT_PRECISION will be used. Sketches computed using different precisions cannot be merged together.

Parameters:

precision - the precision parameter used to compute HLL++ sketch

globally

public Combine.Globally<InputT,byte[]> globally()

Returns a Combine.Globally PTransform that takes an input PCollection<InputT> and returns a PCollection<byte[]> which consists of the HLL++ sketch computed from the elements in the input PCollection.

Returns a singleton PCollection with an "empty sketch" (byte array of length 0) if the input PCollection is empty.

perKey

public <K> Combine.PerKey<K,InputT,byte[]> perKey()

Returns a Combine.PerKey PTransform that takes an input PCollection<KV<K, InputT>> and returns a PCollection<KV<K, byte[]>> which consists of the per-key HLL++ sketch computed from the values matching each key in the input PCollection.