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https://issues.apache.org/jira/browse/BEAM-4461?focusedWorklogId=227003&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-227003
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ASF GitHub Bot logged work on BEAM-4461:
----------------------------------------
Author: ASF GitHub Bot
Created on: 12/Apr/19 23:02
Start Date: 12/Apr/19 23:02
Worklog Time Spent: 10m
Work Description: robinyqiu commented on pull request #8273: [BEAM-4461]
A transform to perform binary joins of PCollections with schemas
URL: https://github.com/apache/beam/pull/8273#discussion_r275078312
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/transforms/Join.java
##########
@@ -0,0 +1,237 @@
+/*
+ * 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 javax.annotation.Nullable;
+import org.apache.beam.sdk.schemas.FieldAccessDescriptor;
+import org.apache.beam.sdk.schemas.Schema;
+import org.apache.beam.sdk.transforms.PTransform;
+import org.apache.beam.sdk.values.PCollection;
+import org.apache.beam.sdk.values.PCollectionTuple;
+import org.apache.beam.sdk.values.Row;
+
+/**
+ * A transform that performs equijoins across two schema {@link PCollection}s.
+ *
+ * <p>This transform allows joins between two input PCollections simply by
specifying the fields to
+ * join on. The resulting {@code PCollection<Row>} will have two fields named
"lhs" and "rhs"
+ * respectively, each with the schema of the corresponding input PCollection.
+ *
+ * <p>For example, the following demonstrates joining two PCollections using a
natural join on the
+ * "user" and "country" fields, where both the left-hand and the right-hand
PCollections have fields
+ * with these names.
+ *
+ * <pre>
+ * {@code PCollection<Row> joined =
pCollection1.apply(Join.innerJoin(pCollection2).using("user", "country"));
+ * }</pre>
+ *
+ * <p>If the right-hand PCollection contains fields with different names to
join against, you can
+ * specify them as follows:
+ *
+ * <pre>{@code PCollection<Row> joined =
pCollection1.apply(Join.innerJoin(pCollection2)
+ * .on(FieldsEqual.left("user", "country").right("otherUser",
"otherCountry")));
+ * }</pre>
+ *
+ * <p>Full outer joins, left outer joins, and right outer joins are also
supported.
+ */
+public class Join {
+ public static final String LHS_TAG = "lhs";
+ public static final String RHS_TAG = "rhs";
+
+ /** Predicate object to specify fields to compare when doing an equi-join. */
+ public static class FieldsEqual {
+ public static Inner left(String... fieldNames) {
+ return new Inner(
+ FieldAccessDescriptor.withFieldNames(fieldNames),
FieldAccessDescriptor.create());
+ }
+
+ public static Inner left(Integer... fieldIds) {
+ return new Inner(
+ FieldAccessDescriptor.withFieldIds(fieldIds),
FieldAccessDescriptor.create());
+ }
+
+ public static Inner left(FieldAccessDescriptor fieldAccessDescriptor) {
+ return new Inner(fieldAccessDescriptor, FieldAccessDescriptor.create());
+ }
+
+ public Inner right(String... fieldNames) {
+ return new Inner(
+ FieldAccessDescriptor.create(),
FieldAccessDescriptor.withFieldNames(fieldNames));
+ }
+
+ public Inner right(Integer... fieldIds) {
+ return new Inner(
+ FieldAccessDescriptor.create(),
FieldAccessDescriptor.withFieldIds(fieldIds));
+ }
+
+ public Inner right(FieldAccessDescriptor fieldAccessDescriptor) {
+ return new Inner(FieldAccessDescriptor.create(), fieldAccessDescriptor);
+ }
+
+ /** Implementation class for FieldsEqual. */
+ public static class Inner {
+ private FieldAccessDescriptor lhs;
+ private FieldAccessDescriptor rhs;
+
+ private Inner(FieldAccessDescriptor lhs, FieldAccessDescriptor rhs) {
+ this.lhs = lhs;
+ this.rhs = rhs;
+ }
+
+ public Inner left(String... fieldNames) {
+ return new Inner(FieldAccessDescriptor.withFieldNames(fieldNames),
rhs);
+ }
+
+ public Inner left(Integer... fieldIds) {
+ return new Inner(FieldAccessDescriptor.withFieldIds(fieldIds), rhs);
+ }
+
+ public Inner left(FieldAccessDescriptor fieldAccessDescriptor) {
+ return new Inner(fieldAccessDescriptor, rhs);
+ }
+
+ public Inner right(String... fieldNames) {
+ return new Inner(lhs,
FieldAccessDescriptor.withFieldNames(fieldNames));
+ }
+
+ public Inner right(Integer... fieldIds) {
+ return new Inner(lhs, FieldAccessDescriptor.withFieldIds(fieldIds));
+ }
+
+ public Inner right(FieldAccessDescriptor fieldAccessDescriptor) {
+ return new Inner(lhs, fieldAccessDescriptor);
+ }
+
+ private Inner resolve(Schema lhsSchema, Schema rhsSchema) {
+ return new Inner(lhs.resolve(lhsSchema), rhs.resolve(rhsSchema));
+ }
+ }
+ }
+
+ /** Perform an inner join. */
+ public static <LhsT, RhsT> Inner<LhsT, RhsT> innerJoin(PCollection<RhsT>
rhs) {
+ return new Inner<>(JoinType.INNER, rhs);
+ }
+
+ /** Perform a full outer join. */
+ public static <LhsT, RhsT> Inner<LhsT, RhsT> fullOuterJoin(PCollection<RhsT>
rhs) {
+ return new Inner<>(JoinType.OUTER, rhs);
+ }
+
+ /** Perform a left outer join. */
+ public static <LhsT, RhsT> Inner<LhsT, RhsT> leftOuterJoin(PCollection<RhsT>
rhs) {
+ return new Inner<>(JoinType.LEFT_OUTER, rhs);
+ }
+
+ /** Perform a right outer join. */
+ public static <LhsT, RhsT> Inner<LhsT, RhsT>
rightOuterJoin(PCollection<RhsT> rhs) {
+ return new Inner<>(JoinType.RIGHT_OUTER, rhs);
+ };
+
+ private enum JoinType {
+ INNER,
+ OUTER,
+ LEFT_OUTER,
+ RIGHT_OUTER
+ };
+
+ /** Implementation class . */
+ public static class Inner<LhsT, RhsT> extends PTransform<PCollection<LhsT>,
PCollection<Row>> {
+ private final JoinType joinType;
+ private final PCollection<RhsT> rhs;
+ @Nullable private final FieldsEqual.Inner predicate;
+
+ private Inner(JoinType joinType, PCollection<RhsT> rhs) {
+ this(joinType, rhs, null);
+ }
+
+ private Inner(JoinType joinType, PCollection<RhsT> rhs, FieldsEqual.Inner
predicate) {
+ this.joinType = joinType;
+ this.rhs = rhs;
+ this.predicate = predicate;
+ }
+
+ /**
+ * Perform a natural join between the PCollections. The fields are
expected to exist in both
+ * PCollections
+ */
+ public Inner<LhsT, RhsT> using(String... fieldNames) {
+ return new Inner<>(joinType, rhs,
FieldsEqual.left(fieldNames).right(fieldNames));
+ }
+
+ /**
+ * Perform a natural join between the PCollections. The fields are
expected to exist in both
+ * PCollections
+ */
+ public Inner<LhsT, RhsT> using(Integer... fieldIds) {
+ return new Inner<>(joinType, rhs,
FieldsEqual.left(fieldIds).right(fieldIds));
+ }
+
+ /**
+ * Perform a natural join between the PCollections. The fields are
expected to exist in both
+ * PCollections
+ */
+ public Inner<LhsT, RhsT> using(FieldAccessDescriptor
fieldAccessDescriptor) {
+ return new Inner<>(
+ joinType, rhs,
FieldsEqual.left(fieldAccessDescriptor).right(fieldAccessDescriptor));
+ }
+
+ /** Join the PCollections using the provided predicate. */
+ public Inner<LhsT, RhsT> on(FieldsEqual.Inner predicate) {
+ return new Inner<>(joinType, rhs, predicate);
+ }
+
+ @Override
+ public PCollection<Row> expand(PCollection lhs) {
Review comment:
Why don't use the more specific type here: `PCollection<LhsT>`
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Issue Time Tracking
-------------------
Worklog Id: (was: 227003)
Time Spent: 25h 40m (was: 25.5h)
> 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
> Labels: triaged
> Time Spent: 25h 40m
> Remaining Estimate: 0h
>
> e.g. JoinBy(fields). Project, Filter, etc.
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