Update readme and register temp tables.

README.md

@@ -11,10 +11,19 @@ The rest of document will use TPC-DS benchmark as an example. We will add conten
 Before running any query, a dataset needs to be setup by creating a `Benchmark` object.   
 
 ```
-import org.apache.spark.sql.parquet.Tables
+import com.databricks.spark.sql.perf.tpcds.Tables
 // Tables in TPC-DS benchmark used by experiments.
-val tables = Tables(sqlContext)
+// dsdgenDir is the location of dsdgen tool installed in your machines.
+val tables = Tables(sqlContext, dsdgenDir, scaleFactor)
+// Generate data.
+tables.genData(location, format, overwrite)
+// Create metastore tables in a specified database for your data.
+// Once tables are created, the current database will be switched to the specified database.
+tables.createExternalTables(location, format, databaseName, overwrite)
+// Or, if you want to create temporary tables
+tables.createTemporaryTables(location, format)
 // Setup TPC-DS experiment
+import com.databricks.spark.sql.perf.tpcds.TPCDS
 val tpcds = new TPCDS (sqlContext = sqlContext)
 ```
 
@@ -31,11 +40,9 @@ For every experiment run (i.e.\ every call of `runExperiment`), Spark SQL Perf w
 While the experiment is running you can use `experiment.html` to list the status.  Once the experiment is complete, the results will be saved to the table sqlPerformance in json.
 
 ```
-// Get experiments results.
-import com.databricks.spark.sql.perf.Results
-val results = Results(resultsLocation = <the root location of performance results>, sqlContext = sqlContext)
-// Get the DataFrame representing all results stored in the dir specified by resultsLocation.
-val allResults = results.allResults
-// Use DataFrame API to get results of a single run.
-allResults.filter("timestamp = 1429132621024")
+// Get all experiments results.
+tpcds.createResultsTable()
+sqlContext.sql("sqlPerformance")
+// Get the result of a particular run by specifying the timestamp of that run.
+sqlContext.sql("sqlPerformance").filter("timestamp = 1429132621024")
 ```

src/main/scala/com/databricks/spark/sql/perf/tpcds/Tables.scala

@@ -100,17 +100,22 @@ class Tables(sqlContext: SQLContext, dsdgenDir: String, scaleFactor: Int) extend
       withPartitionColumns.save(location)
     }
 
-    def createExternalTables(location: String, format: String, databaseName: String, overwrite: Boolean): Unit = {
+    def createExternalTable(location: String, format: String, databaseName: String, overwrite: Boolean): Unit = {
       val qualifiedTableName = databaseName + "." + name
       val tableExists = sqlContext.tableNames(databaseName).contains(name)
       if (overwrite) {
         sqlContext.sql(s"DROP TABLE IF EXISTS $databaseName.$name")
       }
       if (!tableExists || overwrite) {
-        logInfo(s"Creating external table $name in database $databaseName.")
+        logInfo(s"Creating external table $name in database $databaseName using data stored in $location.")
         sqlContext.createExternalTable(qualifiedTableName, location, format)
       }
     }
+
+    def createTemporaryTable(location: String, format: String): Unit = {
+      logInfo(s"Creating temporary table $name using data stored in $location.")
+      sqlContext.read.format(format).load(location).registerTempTable(name)
+    }
   }
 
   def genData(location: String, format: String, overwrite: Boolean): Unit = {
@@ -126,7 +131,17 @@ class Tables(sqlContext: SQLContext, dsdgenDir: String, scaleFactor: Int) extend
     tables.foreach { table =>
       val tableLocation =
         location + File.separator + format + File.separator + "sf" + scaleFactor + File.separator + table.name
-      table.createExternalTables(tableLocation, format, databaseName, overwrite)
+      table.createExternalTable(tableLocation, format, databaseName, overwrite)
+    }
+    sqlContext.sql(s"USE $databaseName")
+    logInfo(s"The current database has been set to $databaseName.")
+  }
+
+  def createTemporaryTables(location: String, format: String): Unit = {
+    tables.foreach { table =>
+      val tableLocation =
+        location + File.separator + format + File.separator + "sf" + scaleFactor + File.separator + table.name
+      table.createTemporaryTable(tableLocation, format)
     }
   }