Add Join operator support for Generic JDBC platform

wayang-platforms/wayang-generic-jdbc/src/main/java/org/apache/wayang/genericjdbc/mapping/JoinMapping.java

@@ -0,0 +1,70 @@
+/*
+ * 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.wayang.genericjdbc.mapping;
+
+import org.apache.wayang.basic.data.Record;
+import org.apache.wayang.basic.operators.JoinOperator;
+import org.apache.wayang.core.mapping.Mapping;
+import org.apache.wayang.core.mapping.OperatorPattern;
+import org.apache.wayang.core.mapping.PlanTransformation;
+import org.apache.wayang.core.mapping.ReplacementSubplanFactory;
+import org.apache.wayang.core.mapping.SubplanPattern;
+import org.apache.wayang.core.types.DataSetType;
+import org.apache.wayang.genericjdbc.operators.GenericJdbcJoinOperator;
+import org.apache.wayang.genericjdbc.platform.GenericJdbcPlatform;
+
+import java.util.Collection;
+import java.util.Collections;
+
+/**
+ * Mapping from {@link JoinOperator} to {@link GenericJdbcJoinOperator}.
+ */
+@SuppressWarnings("unchecked")
+public class JoinMapping implements Mapping {
+
+    @Override
+    public Collection<PlanTransformation> getTransformations() {
+        return Collections.singleton(new PlanTransformation(
+                this.createSubplanPattern(),
+                this.createReplacementSubplanFactory(),
+                GenericJdbcPlatform.getInstance()
+        ));
+    }
+
+    private SubplanPattern createSubplanPattern() {
+
+        final OperatorPattern<JoinOperator<Record, Record, ?>> operatorPattern =
+                new OperatorPattern<>(
+                        "join",
+                        new JoinOperator<>(null, null,
+                                DataSetType.createDefault(Record.class),
+                                DataSetType.createDefault(Record.class)),
+                        false
+                );
+
+        return SubplanPattern.createSingleton(operatorPattern);
+    }
+
+    private ReplacementSubplanFactory createReplacementSubplanFactory() {
+        return new ReplacementSubplanFactory.OfSingleOperators<JoinOperator>(
+                (matchedOperator, epoch) ->
+                        new GenericJdbcJoinOperator<>(matchedOperator).at(epoch)
+        );
+    }
+}

wayang-platforms/wayang-generic-jdbc/src/main/java/org/apache/wayang/genericjdbc/mapping/Mappings.java

@@ -30,7 +30,8 @@ public class Mappings {
 
     public static final Collection<Mapping> ALL = Arrays.asList(
             new FilterMapping(),
-            new ProjectionMapping()
+            new ProjectionMapping(),
+            new JoinMapping()
     );
 
 }

wayang-platforms/wayang-generic-jdbc/src/main/java/org/apache/wayang/genericjdbc/operators/GenericJdbcJoinOperator.java

@@ -0,0 +1,47 @@
+/*
+ * 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.wayang.genericjdbc.operators;
+
+import org.apache.wayang.basic.data.Record;
+import org.apache.wayang.basic.operators.JoinOperator;
+import org.apache.wayang.core.function.TransformationDescriptor;
+import org.apache.wayang.jdbc.operators.JdbcJoinOperator;
+
+/**
+ * Generic JDBC implementation of the {@link JoinOperator}.
+ */
+public class GenericJdbcJoinOperator<KeyType>
+        extends JdbcJoinOperator<KeyType>
+        implements GenericJdbcExecutionOperator {
+
+    public GenericJdbcJoinOperator(
+            TransformationDescriptor<Record, KeyType> keyDescriptor0,
+            TransformationDescriptor<Record, KeyType> keyDescriptor1) {
+        super(keyDescriptor0, keyDescriptor1);
+    }
+
+    public GenericJdbcJoinOperator(JoinOperator<Record, Record, KeyType> that) {
+        super(that);
+    }
+
+    @Override
+    protected GenericJdbcJoinOperator<KeyType> createCopy() {
+        return new GenericJdbcJoinOperator<>(this);
+    }
+}