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https://issues.apache.org/jira/browse/BEAM-4461?focusedWorklogId=143366&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-143366
]
ASF GitHub Bot logged work on BEAM-4461:
----------------------------------------
Author: ASF GitHub Bot
Created on: 12/Sep/18 04:31
Start Date: 12/Sep/18 04:31
Worklog Time Spent: 10m
Work Description: reuvenlax commented on a change in pull request #6316:
[BEAM-4461] Add Unnest transform.
URL: https://github.com/apache/beam/pull/6316#discussion_r216893940
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/transforms/Unnest.java
##########
@@ -0,0 +1,182 @@
+/*
+ * 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.schemas.transforms;
+
+import com.google.auto.value.AutoValue;
+import com.google.common.collect.Lists;
+import java.util.List;
+import org.apache.beam.sdk.annotations.Experimental;
+import org.apache.beam.sdk.annotations.Experimental.Kind;
+import org.apache.beam.sdk.schemas.Schema;
+import org.apache.beam.sdk.schemas.Schema.Field;
+import org.apache.beam.sdk.transforms.DoFn;
+import org.apache.beam.sdk.transforms.PTransform;
+import org.apache.beam.sdk.transforms.ParDo;
+import org.apache.beam.sdk.transforms.SerializableFunction;
+import org.apache.beam.sdk.values.PCollection;
+import org.apache.beam.sdk.values.Row;
+/**
+ * A {@link PTransform} to unnest nested rows.
+ *
+ * <p>For example, consider a Row with the following nestedschema:
+ *
+ * <p>UserEvent Schema: userid: INT64 timestamp: DATETIME location: LatLong
+ *
+ * <p>LatLong Schema: latitude: DOUBLE longitude: DOUBLE
+ *
+ * <p>After unnesting, all of the rows will be converted to rows satisfying
the following schema:
+ *
+ * <p>UserEvent Schema: userid: INT64 timestamp: DATETIME location.latitude:
DOUBLE
+ * location.longitude: DOUBLE
+ *
+ * <p>By default nested names are concatenated to generated the unnested name,
however {@link
+ * Unnest.Inner#withFieldNameFunction} can be used to specify a custom naming
policy.
+ *
+ * <p>Note that currently array and map values are not unnested.
+ */
+@Experimental(Kind.SCHEMAS)
+public class Unnest {
+ public static <T> Inner<T> create() {
+ return new AutoValue_Unnest_Inner.Builder<T>()
+ .setMaxLevels(Integer.MAX_VALUE)
+ .setFieldNameFunction(CONCAT_FIELD_NAMES)
+ .build();
+ }
+ /**
+ * This is the default naming policy for naming fields. Every field name in
the path to a given
+ * field is concated with . characters.
+ */
+ public static final SerializableFunction<List<String>, String>
CONCAT_FIELD_NAMES =
+ l -> {
+ return String.join(".", l);
+ };
+ /**
+ * This policy keeps the raw nested field name. If two differently-nested
fields have the same
+ * name, unnesting will fail with this policy.
+ */
+ public static final SerializableFunction<List<String>, String>
KEEP_NESTED_NAME =
+ l -> {
+ return l.get(l.size() - 1);
+ };
+ /** Returns the result of unnesting the given schema. The default naming
policy is used. */
+ static Schema getUnnestedSchema(Schema schema, int maxLevels) {
+ List<String> nameComponents = Lists.newArrayList();
+ return getUnnestedSchema(schema, nameComponents, CONCAT_FIELD_NAMES,
maxLevels, 0);
+ }
+ /** Returns the result of unnesting the given schema with the given naming
policy. */
+ static Schema getUnnestedSchema(
+ Schema schema, int maxLevels, SerializableFunction<List<String>, String>
fn) {
+ List<String> nameComponents = Lists.newArrayList();
+ return getUnnestedSchema(schema, nameComponents, fn, maxLevels, 0);
+ }
+
+ private static Schema getUnnestedSchema(
+ Schema schema,
+ List<String> nameComponents,
+ SerializableFunction<List<String>, String> fn,
+ int maxLevel,
+ int currentLevel) {
+ Schema.Builder builder = Schema.builder();
+ for (Field field : schema.getFields()) {
+ nameComponents.add(field.getName());
+ if (field.getType().getTypeName().isCompositeType() && currentLevel <
maxLevel) {
Review comment:
Why?
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Issue Time Tracking
-------------------
Worklog Id: (was: 143366)
Time Spent: 7h 40m (was: 7.5h)
> Create a library of useful transforms that use schemas
> ------------------------------------------------------
>
> Key: BEAM-4461
> URL: https://issues.apache.org/jira/browse/BEAM-4461
> Project: Beam
> Issue Type: Sub-task
> Components: sdk-java-core
> Reporter: Reuven Lax
> Assignee: Reuven Lax
> Priority: Major
> Time Spent: 7h 40m
> Remaining Estimate: 0h
>
> e.g. JoinBy(fields). Project, Filter, etc.
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