[SQL] SPARK-1333 First draft of java API

WIP: Some work remains...
 * [x] Hive support
 * [x] Tests
 * [x] Update docs

Feedback welcome!

Author: Michael Armbrust <michael@databricks.com>

Closes #248 from marmbrus/javaSchemaRDD and squashes the following commits:

b393913 [Michael Armbrust] @srowen 's java style suggestions.
f531eb1 [Michael Armbrust] Address matei's comments.
33a1b1a [Michael Armbrust] Ignore JavaHiveSuite.
822f626 [Michael Armbrust] improve docs.
ab91750 [Michael Armbrust] Improve Java SQL API: * Change JavaRow => Row * Add support for querying RDDs of JavaBeans * Docs * Tests * Hive support
0b859c8 [Michael Armbrust] First draft of java API.

1 files changed, 99 insertions, 0 deletions

diff --git a/examples/src/main/java/org/apache/spark/examples/sql/JavaSparkSQL.java b/examples/src/main/java/org/apache/spark/examples/sql/JavaSparkSQL.java
new file mode 100644
index 0000000000..e8e63d2745
--- /dev/null
+++ b/examples/src/main/java/org/apache/spark/examples/sql/JavaSparkSQL.java
@@ -0,0 +1,99 @@
+/*
+ * 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.spark.examples.sql;
+
+import java.io.Serializable;
+import java.util.List;
+
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.api.java.JavaSparkContext;
+import org.apache.spark.api.java.function.Function;
+import org.apache.spark.api.java.function.VoidFunction;
+
+import org.apache.spark.sql.api.java.JavaSQLContext;
+import org.apache.spark.sql.api.java.JavaSchemaRDD;
+import org.apache.spark.sql.api.java.Row;
+
+public class JavaSparkSQL {
+  public static class Person implements Serializable {
+    private String name;
+    private int age;
+
+    String getName() {
+      return name;
+    }
+
+    void setName(String name) {
+      this.name = name;
+    }
+
+    int getAge() {
+      return age;
+    }
+
+    void setAge(int age) {
+      this.age = age;
+    }
+  }
+
+  public static void main(String[] args) throws Exception {
+    JavaSparkContext ctx = new JavaSparkContext("local", "JavaSparkSQL",
+        System.getenv("SPARK_HOME"), JavaSparkContext.jarOfClass(JavaSparkSQL.class));
+    JavaSQLContext sqlCtx = new JavaSQLContext(ctx);
+
+    // Load a text file and convert each line to a Java Bean.
+    JavaRDD<Person> people = ctx.textFile("examples/src/main/resources/people.txt").map(
+      new Function<String, Person>() {
+        public Person call(String line) throws Exception {
+          String[] parts = line.split(",");
+
+          Person person = new Person();
+          person.setName(parts[0]);
+          person.setAge(Integer.parseInt(parts[1].trim()));
+
+          return person;
+        }
+      });
+
+    // Apply a schema to an RDD of Java Beans and register it as a table.
+    JavaSchemaRDD schemaPeople = sqlCtx.applySchema(people, Person.class);
+    schemaPeople.registerAsTable("people");
+
+    // SQL can be run over RDDs that have been registered as tables.
+    JavaSchemaRDD teenagers = sqlCtx.sql("SELECT name FROM people WHERE age >= 13 AND age <= 19");
+
+    // The results of SQL queries are SchemaRDDs and support all the normal RDD operations.
+    // The columns of a row in the result can be accessed by ordinal.
+    List<String> teenagerNames = teenagers.map(new Function<Row, String>() {
+      public String call(Row row) {
+        return "Name: " + row.getString(0);
+      }
+    }).collect();
+
+    // JavaSchemaRDDs can be saved as parquet files, maintaining the schema information.
+    schemaPeople.saveAsParquetFile("people.parquet");
+
+    // Read in the parquet file created above.  Parquet files are self-describing so the schema is preserved.
+    // The result of loading a parquet file is also a JavaSchemaRDD.
+    JavaSchemaRDD parquetFile = sqlCtx.parquetFile("people.parquet");
+
+    //Parquet files can also be registered as tables and then used in SQL statements.
+    parquetFile.registerAsTable("parquetFile");
+    JavaSchemaRDD teenagers2 = sqlCtx.sql("SELECT name FROM parquetFile WHERE age >= 13 AND age <= 19");
+  }
+}