[SPARK-14525][SQL] Make DataFrameWrite.save work for jdbc

## What changes were proposed in this pull request?

This change modifies the implementation of DataFrameWriter.save such that it works with jdbc, and the call to jdbc merely delegates to save.

## How was this patch tested?

This was tested via unit tests in the JDBCWriteSuite, of which I added one new test to cover this scenario.

## Additional details

rxin This seems to have been most recently touched by you and was also commented on in the JIRA.

This contribution is my original work and I license the work to the project under the project's open source license.

Author: Justin Pihony <[email protected]>
Author: Justin Pihony <[email protected]>

Closes #12601 from JustinPihony/jdbc_reconciliation.

Author: JustinPihony

docs/sql-programming-guide.md

@@ -1100,9 +1100,13 @@ CREATE TEMPORARY VIEW jdbcTable
 USING org.apache.spark.sql.jdbc
 OPTIONS (
   url "jdbc:postgresql:dbserver",
-  dbtable "schema.tablename"
+  dbtable "schema.tablename",
+  user 'username', 
+  password 'password'
 )
 
+INSERT INTO TABLE jdbcTable 
+SELECT * FROM resultTable
 {% endhighlight %}
 
 </div>

examples/src/main/java/org/apache/spark/examples/sql/JavaSQLDataSourceExample.java

@@ -22,6 +22,7 @@
 import java.util.Arrays;
 import java.util.List;
 // $example off:schema_merging$
+import java.util.Properties;
 
 // $example on:basic_parquet_example$
 import org.apache.spark.api.java.JavaRDD;
@@ -235,13 +236,33 @@ private static void runJsonDatasetExample(SparkSession spark) {
 
   private static void runJdbcDatasetExample(SparkSession spark) {
     // $example on:jdbc_dataset$
+    // Note: JDBC loading and saving can be achieved via either the load/save or jdbc methods
+    // Loading data from a JDBC source
     Dataset<Row> jdbcDF = spark.read()
       .format("jdbc")
       .option("url", "jdbc:postgresql:dbserver")
       .option("dbtable", "schema.tablename")
       .option("user", "username")
       .option("password", "password")
       .load();
+
+    Properties connectionProperties = new Properties();
+    connectionProperties.put("user", "username");
+    connectionProperties.put("password", "password");
+    Dataset<Row> jdbcDF2 = spark.read()
+      .jdbc("jdbc:postgresql:dbserver", "schema.tablename", connectionProperties);
+
+    // Saving data to a JDBC source
+    jdbcDF.write()
+      .format("jdbc")
+      .option("url", "jdbc:postgresql:dbserver")
+      .option("dbtable", "schema.tablename")
+      .option("user", "username")
+      .option("password", "password")
+      .save();
+
+    jdbcDF2.write()
+      .jdbc("jdbc:postgresql:dbserver", "schema.tablename", connectionProperties);
     // $example off:jdbc_dataset$
   }
 }

examples/src/main/python/sql/datasource.py

@@ -143,13 +143,32 @@ def json_dataset_example(spark):
 
 def jdbc_dataset_example(spark):
     # $example on:jdbc_dataset$
+    # Note: JDBC loading and saving can be achieved via either the load/save or jdbc methods
+    # Loading data from a JDBC source
     jdbcDF = spark.read \
         .format("jdbc") \
         .option("url", "jdbc:postgresql:dbserver") \
         .option("dbtable", "schema.tablename") \
         .option("user", "username") \
         .option("password", "password") \
         .load()
+
+    jdbcDF2 = spark.read \
+        .jdbc("jdbc:postgresql:dbserver", "schema.tablename",
+              properties={"user": "username", "password": "password"})
+
+    # Saving data to a JDBC source
+    jdbcDF.write \
+        .format("jdbc") \
+        .option("url", "jdbc:postgresql:dbserver") \
+        .option("dbtable", "schema.tablename") \
+        .option("user", "username") \
+        .option("password", "password") \
+        .save()
+
+    jdbcDF2.write \
+        .jdbc("jdbc:postgresql:dbserver", "schema.tablename",
+              properties={"user": "username", "password": "password"})
     # $example off:jdbc_dataset$
 
 

examples/src/main/r/RSparkSQLExample.R

@@ -204,7 +204,11 @@ results <- collect(sql("FROM src SELECT key, value"))
 
 
 # $example on:jdbc_dataset$
+# Loading data from a JDBC source
 df <- read.jdbc("jdbc:postgresql:dbserver", "schema.tablename", user = "username", password = "password")
+
+# Saving data to a JDBC source
+write.jdbc(df, "jdbc:postgresql:dbserver", "schema.tablename", user = "username", password = "password")
 # $example off:jdbc_dataset$
 
 # Stop the SparkSession now

examples/src/main/scala/org/apache/spark/examples/sql/SQLDataSourceExample.scala

@@ -16,6 +16,8 @@
  */
 package org.apache.spark.examples.sql
 
+import java.util.Properties
+
 import org.apache.spark.sql.SparkSession
 
 object SQLDataSourceExample {
@@ -148,13 +150,33 @@ object SQLDataSourceExample {
 
   private def runJdbcDatasetExample(spark: SparkSession): Unit = {
     // $example on:jdbc_dataset$
+    // Note: JDBC loading and saving can be achieved via either the load/save or jdbc methods
+    // Loading data from a JDBC source
     val jdbcDF = spark.read
       .format("jdbc")
       .option("url", "jdbc:postgresql:dbserver")
       .option("dbtable", "schema.tablename")
       .option("user", "username")
       .option("password", "password")
       .load()
+
+    val connectionProperties = new Properties()
+    connectionProperties.put("user", "username")
+    connectionProperties.put("password", "password")
+    val jdbcDF2 = spark.read
+      .jdbc("jdbc:postgresql:dbserver", "schema.tablename", connectionProperties)
+
+    // Saving data to a JDBC source
+    jdbcDF.write
+      .format("jdbc")
+      .option("url", "jdbc:postgresql:dbserver")
+      .option("dbtable", "schema.tablename")
+      .option("user", "username")
+      .option("password", "password")
+      .save()
+
+    jdbcDF2.write
+      .jdbc("jdbc:postgresql:dbserver", "schema.tablename", connectionProperties)
     // $example off:jdbc_dataset$
   }
 }

sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala

@@ -425,62 +425,11 @@ final class DataFrameWriter[T] private[sql](ds: Dataset[T]) {
   def jdbc(url: String, table: String, connectionProperties: Properties): Unit = {
     assertNotPartitioned("jdbc")
     assertNotBucketed("jdbc")
-
-    // to add required options like URL and dbtable
-    val params = extraOptions.toMap ++ Map("url" -> url, "dbtable" -> table)
-    val jdbcOptions = new JDBCOptions(params)
-    val jdbcUrl = jdbcOptions.url
-    val jdbcTable = jdbcOptions.table
-
-    val props = new Properties()
-    extraOptions.foreach { case (key, value) =>
-      props.put(key, value)
-    }
     // connectionProperties should override settings in extraOptions
-    props.putAll(connectionProperties)
-    val conn = JdbcUtils.createConnectionFactory(jdbcUrl, props)()
-
-    try {
-      var tableExists = JdbcUtils.tableExists(conn, jdbcUrl, jdbcTable)
-
-      if (mode == SaveMode.Ignore && tableExists) {
-        return
-      }
-
-      if (mode == SaveMode.ErrorIfExists && tableExists) {
-        sys.error(s"Table $jdbcTable already exists.")
-      }
-
-      if (mode == SaveMode.Overwrite && tableExists) {
-        if (jdbcOptions.isTruncate &&
-            JdbcUtils.isCascadingTruncateTable(jdbcUrl) == Some(false)) {
-          JdbcUtils.truncateTable(conn, jdbcTable)
-        } else {
-          JdbcUtils.dropTable(conn, jdbcTable)
-          tableExists = false
-        }
-      }
-
-      // Create the table if the table didn't exist.
-      if (!tableExists) {
-        val schema = JdbcUtils.schemaString(df, jdbcUrl)
-        // To allow certain options to append when create a new table, which can be
-        // table_options or partition_options.
-        // E.g., "CREATE TABLE t (name string) ENGINE=InnoDB DEFAULT CHARSET=utf8"
-        val createtblOptions = jdbcOptions.createTableOptions
-        val sql = s"CREATE TABLE $jdbcTable ($schema) $createtblOptions"
-        val statement = conn.createStatement
-        try {
-          statement.executeUpdate(sql)
-        } finally {
-          statement.close()
-        }
-      }
-    } finally {
-      conn.close()
-    }
-
-    JdbcUtils.saveTable(df, jdbcUrl, jdbcTable, props)
+    this.extraOptions = this.extraOptions ++ (connectionProperties.asScala)
+    // explicit url and dbtable should override all
+    this.extraOptions += ("url" -> url, "dbtable" -> table)
+    format("jdbc").save()
   }
 
   /**

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCOptions.scala

@@ -27,10 +27,12 @@ class JDBCOptions(
   // ------------------------------------------------------------
   // Required parameters
   // ------------------------------------------------------------
+  require(parameters.isDefinedAt("url"), "Option 'url' is required.")
+  require(parameters.isDefinedAt("dbtable"), "Option 'dbtable' is required.")
   // a JDBC URL
-  val url = parameters.getOrElse("url", sys.error("Option 'url' not specified"))
+  val url = parameters("url")
   // name of table
-  val table = parameters.getOrElse("dbtable", sys.error("Option 'dbtable' not specified"))
+  val table = parameters("dbtable")
 
   // ------------------------------------------------------------
   // Optional parameter list
@@ -44,6 +46,11 @@ class JDBCOptions(
   // the number of partitions
   val numPartitions = parameters.getOrElse("numPartitions", null)
 
+  require(partitionColumn == null ||
+    (lowerBound != null && upperBound != null && numPartitions != null),
+    "If 'partitionColumn' is specified then 'lowerBound', 'upperBound'," +
+      " and 'numPartitions' are required.")
+
   // ------------------------------------------------------------
   // The options for DataFrameWriter
   // ------------------------------------------------------------

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JdbcRelationProvider.scala

@@ -19,37 +19,102 @@ package org.apache.spark.sql.execution.datasources.jdbc
 
 import java.util.Properties
 
-import org.apache.spark.sql.SQLContext
-import org.apache.spark.sql.sources.{BaseRelation, DataSourceRegister, RelationProvider}
+import scala.collection.JavaConverters.mapAsJavaMapConverter
 
-class JdbcRelationProvider extends RelationProvider with DataSourceRegister {
+import org.apache.spark.sql.{AnalysisException, DataFrame, SaveMode, SQLContext}
+import org.apache.spark.sql.sources.{BaseRelation, CreatableRelationProvider, DataSourceRegister, RelationProvider}
+
+class JdbcRelationProvider extends CreatableRelationProvider
+  with RelationProvider with DataSourceRegister {
 
   override def shortName(): String = "jdbc"
 
-  /** Returns a new base relation with the given parameters. */
   override def createRelation(
       sqlContext: SQLContext,
       parameters: Map[String, String]): BaseRelation = {
     val jdbcOptions = new JDBCOptions(parameters)
-    if (jdbcOptions.partitionColumn != null
-      && (jdbcOptions.lowerBound == null
-        || jdbcOptions.upperBound == null
-        || jdbcOptions.numPartitions == null)) {
-      sys.error("Partitioning incompletely specified")
-    }
+    val partitionColumn = jdbcOptions.partitionColumn
+    val lowerBound = jdbcOptions.lowerBound
+    val upperBound = jdbcOptions.upperBound
+    val numPartitions = jdbcOptions.numPartitions
 
-    val partitionInfo = if (jdbcOptions.partitionColumn == null) {
+    val partitionInfo = if (partitionColumn == null) {
       null
     } else {
       JDBCPartitioningInfo(
-        jdbcOptions.partitionColumn,
-        jdbcOptions.lowerBound.toLong,
-        jdbcOptions.upperBound.toLong,
-        jdbcOptions.numPartitions.toInt)
+        partitionColumn, lowerBound.toLong, upperBound.toLong, numPartitions.toInt)
     }
     val parts = JDBCRelation.columnPartition(partitionInfo)
     val properties = new Properties() // Additional properties that we will pass to getConnection
     parameters.foreach(kv => properties.setProperty(kv._1, kv._2))
     JDBCRelation(jdbcOptions.url, jdbcOptions.table, parts, properties)(sqlContext.sparkSession)
   }
+
+  /*
+   * The following structure applies to this code:
+   *                 |    tableExists            |          !tableExists
+   *------------------------------------------------------------------------------------
+   * Ignore          | BaseRelation              | CreateTable, saveTable, BaseRelation
+   * ErrorIfExists   | ERROR                     | CreateTable, saveTable, BaseRelation
+   * Overwrite*      | (DropTable, CreateTable,) | CreateTable, saveTable, BaseRelation
+   *                 | saveTable, BaseRelation   |
+   * Append          | saveTable, BaseRelation   | CreateTable, saveTable, BaseRelation
+   *
+   * *Overwrite & tableExists with truncate, will not drop & create, but instead truncate
+   */
+  override def createRelation(
+      sqlContext: SQLContext,
+      mode: SaveMode,
+      parameters: Map[String, String],
+      data: DataFrame): BaseRelation = {
+    val jdbcOptions = new JDBCOptions(parameters)
+    val url = jdbcOptions.url
+    val table = jdbcOptions.table
+
+    val props = new Properties()
+    props.putAll(parameters.asJava)
+    val conn = JdbcUtils.createConnectionFactory(url, props)()
+
+    try {
+      val tableExists = JdbcUtils.tableExists(conn, url, table)
+
+      val (doCreate, doSave) = (mode, tableExists) match {
+        case (SaveMode.Ignore, true) => (false, false)
+        case (SaveMode.ErrorIfExists, true) => throw new AnalysisException(
+          s"Table or view '$table' already exists, and SaveMode is set to ErrorIfExists.")
+        case (SaveMode.Overwrite, true) =>
+          if (jdbcOptions.isTruncate && JdbcUtils.isCascadingTruncateTable(url) == Some(false)) {
+            JdbcUtils.truncateTable(conn, table)
+            (false, true)
+          } else {
+            JdbcUtils.dropTable(conn, table)
+            (true, true)
+          }
+        case (SaveMode.Append, true) => (false, true)
+        case (_, true) => throw new IllegalArgumentException(s"Unexpected SaveMode, '$mode'," +
+          " for handling existing tables.")
+        case (_, false) => (true, true)
+      }
+
+      if (doCreate) {
+        val schema = JdbcUtils.schemaString(data, url)
+        // To allow certain options to append when create a new table, which can be
+        // table_options or partition_options.
+        // E.g., "CREATE TABLE t (name string) ENGINE=InnoDB DEFAULT CHARSET=utf8"
+        val createtblOptions = jdbcOptions.createTableOptions
+        val sql = s"CREATE TABLE $table ($schema) $createtblOptions"
+        val statement = conn.createStatement
+        try {
+          statement.executeUpdate(sql)
+        } finally {
+          statement.close()
+        }
+      }
+      if (doSave) JdbcUtils.saveTable(data, url, table, props)
+    } finally {
+      conn.close()
+    }
+
+    createRelation(sqlContext, parameters)
+  }
 }