| /* |
| * Copyright 2019, Verizon Media. |
| * Licensed under the terms of the Apache License 2.0. See LICENSE file at the project root for terms. |
| */ |
| |
| package com.yahoo.sketches.hive.quantiles; |
| |
| import java.util.Comparator; |
| |
| import org.apache.hadoop.hive.ql.exec.Description; |
| import org.apache.hadoop.hive.ql.exec.UDF; |
| import org.apache.hadoop.io.BytesWritable; |
| |
| import com.yahoo.memory.Memory; |
| import com.yahoo.sketches.ArrayOfStringsSerDe; |
| import com.yahoo.sketches.quantiles.ItemsSketch; |
| |
| @Description(name = "GetN", value = "_FUNC_(sketch)", |
| extended = " Returns the total number of observed input values (stream length) " |
| + "from a given ItemsSketch<String>.") |
| public class GetNFromStringsSketchUDF extends UDF { |
| |
| /** |
| * Returns N from a given sketch |
| * @param serializedSketch serialized sketch |
| * @return stream length |
| */ |
| public Long evaluate(final BytesWritable serializedSketch) { |
| if (serializedSketch == null) { return null; } |
| final ItemsSketch<String> sketch = ItemsSketch.getInstance( |
| Memory.wrap(serializedSketch.getBytes()), |
| Comparator.naturalOrder(), |
| new ArrayOfStringsSerDe() |
| ); |
| return sketch.getN(); |
| } |
| |
| } |