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https://issues.apache.org/jira/browse/BEAM-7013?focusedWorklogId=293428&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-293428
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ASF GitHub Bot logged work on BEAM-7013:
----------------------------------------
Author: ASF GitHub Bot
Created on: 12/Aug/19 21:57
Start Date: 12/Aug/19 21:57
Worklog Time Spent: 10m
Work Description: robinyqiu commented on pull request #9144: [BEAM-7013]
Integrating ZetaSketch's HLL++ algorithm with Beam
URL: https://github.com/apache/beam/pull/9144#discussion_r313143078
##########
File path:
sdks/java/extensions/zetasketch/src/main/java/org/apache/beam/sdk/extensions/zetasketch/HllCountInitFn.java
##########
@@ -0,0 +1,153 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.beam.sdk.extensions.zetasketch;
+
+import static
org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkArgument;
+
+import com.google.zetasketch.HyperLogLogPlusPlus;
+import com.google.zetasketch.shaded.com.google.protobuf.ByteString;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.sdk.coders.CoderRegistry;
+import org.apache.beam.sdk.transforms.Combine;
+
+/**
+ * {@link Combine.CombineFn} for the {@link HllCount.Init} combiner.
+ *
+ * @param <InputT> type of input values to the function
+ * @param <HllT> type of the HLL++ sketch to compute
+ */
+abstract class HllCountInitFn<InputT, HllT>
+ extends Combine.CombineFn<InputT, HyperLogLogPlusPlus<HllT>, byte[]> {
+
+ private int precision;
+
+ private HllCountInitFn() {
+ setPrecision(HllCount.DEFAULT_PRECISION);
+ }
+
+ int getPrecision() {
+ return precision;
+ }
+
+ // Should not be called at pipeline execution time.
Review comment:
> Would expand on this (e.g., what happens if the advice is ignored?), and
also turn it into Javadoc: "this will only have an effect if called before ...;
any updates after that will be discarded; only intended to be used from within
a builder" or similar.
Done! PTAL.
> Since you have a builder in the caller class, I was wondering whether
there is a good way to only allow setting the precision at construction time,
which would be cleaner. But I think it would require a enum for the allowed
types in the builder... (I'll think about it some more).
Exactly! I think we have went through the same thought process. (In an
earlier version of the code, the `precision` field is a `final` field so this
problem did not exist, but after a few rounds of refactoring we need to call it
from within a builder.) To make the coder cleaner, I did not add the extra
enum, but created this package-private function. Let me know if you have better
ideas!
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Issue Time Tracking
-------------------
Worklog Id: (was: 293428)
Time Spent: 13h 40m (was: 13.5h)
> A new count distinct transform based on BigQuery compatible HyperLogLog++
> implementation
> ----------------------------------------------------------------------------------------
>
> Key: BEAM-7013
> URL: https://issues.apache.org/jira/browse/BEAM-7013
> Project: Beam
> Issue Type: New Feature
> Components: extensions-java-sketching, sdk-java-core
> Reporter: Yueyang Qiu
> Assignee: Yueyang Qiu
> Priority: Major
> Fix For: 2.16.0
>
> Time Spent: 13h 40m
> Remaining Estimate: 0h
>
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