adding partition option to SQL workload

cli/src/main/scala/com/ibm/sparktc/sparkbench/workload/sql/SQLWorkload.scala

@@ -39,7 +39,8 @@ object SQLWorkload extends WorkloadDefaults {
       output = m.get("output").map(_.asInstanceOf[String]),
       saveMode = getOrDefault[String](m, "save-mode", SaveModes.error),
       queryStr = getOrThrow(m, "query").asInstanceOf[String],
-      cache = getOrDefault[Boolean](m, "cache", false)
+      cache = getOrDefault[Boolean](m, "cache", false),
+      numPartitions = m.get("partitions").map(_.asInstanceOf[Int])
     )
 
 }
@@ -48,7 +49,9 @@ case class SQLWorkload (input: Option[String],
                         output: Option[String] = None,
                         saveMode: String,
                         queryStr: String,
-                        cache: Boolean) extends Workload {
+                        cache: Boolean,
+                        numPartitions: Option[Int] = None
+                       ) extends Workload {
 
   def loadFromDisk(spark: SparkSession): (Long, DataFrame) = time {
     val df = load(spark, input.get)
@@ -62,7 +65,12 @@ case class SQLWorkload (input: Option[String],
   }
 
   def save(res: DataFrame, where: String, spark: SparkSession): (Long, Unit) = time {
-    writeToDisk(where, saveMode, res, spark)
+    if(numPartitions.nonEmpty){
+      writeToDisk(where, saveMode, res.repartition(numPartitions.get), spark)
+    }
+    else {
+      writeToDisk(where, saveMode, res, spark)
+    }
   }
 
   override def doWorkload(df: Option[DataFrame] = None, spark: SparkSession): DataFrame = {

docs/_workloads/sql.md

@@ -26,6 +26,8 @@ select `0` from input where `0` < -0.9
 | save-mode | no | errorifexists | Options are "errorifexists", "ignore" (no-op if exists), and "overwrite" |
 | query    | yes      | --    | the sql query to perform. The table name must be "input" as shown in the examples above. |
 | cache       | no       | false | whether the dataset should be cached after being read from disk |
+| partitions | no| Natural partitioning | If users specify `output` for this workload, they can optionally repartion the dataset using this option.|
+
 
 #### Examples
 
@@ -45,4 +47,15 @@ select `0` from input where `0` < -0.9
   query = "select `0` from input where `0` < -0.9"
   cache = true
 }
+```
+
+```hocon
+{
+  name = "sql"
+  input = "/tmp/generated-kmeans-data.parquet"
+  query = "select `0` from input where `0` < -0.9"
+  cache = true
+  output = "hdfs:///query-output-in-three-partitions.csv"
+  partitions = 3 // will repartition the dataset before writing out
+}
 ```