Applying pre-partitioning to DataSources.

datasource/src/main/scala/org/locationtech/rasterframes/datasource/raster/RasterSourceRelation.scala

@@ -69,6 +69,9 @@ case class RasterSourceRelation(
     catalog.schema.fields.filter(f => !catalogTable.bandColumnNames.contains(f.name))
   }
 
+  protected def defaultNumPartitions: Int =
+    sqlContext.sparkSession.sessionState.conf.numShufflePartitions
+
   override def schema: StructType = {
     val tileSchema = schemaOf[ProjectedRasterTile]
     val paths = for {
@@ -84,10 +87,11 @@ case class RasterSourceRelation(
   override def buildScan(): RDD[Row] = {
     import sqlContext.implicits._
 
-    // The general transformaion is:
+    // The general transformation is:
     // input -> path -> src -> ref -> tile
     // Each step is broken down for readability
     val inputs: DataFrame = sqlContext.table(catalogTable.tableName)
+      .repartition(defaultNumPartitions)
 
     // Basically renames the input columns to have the '_path' suffix
     val pathsAliasing = for {
@@ -112,7 +116,7 @@ case class RasterSourceRelation(
 
     val df = if (lazyTiles) {
       // Expand RasterSource into multiple columns per band, and multiple rows per tile
-      // There's some unintentional fragililty here in that the structure of the expression
+      // There's some unintentional fragility here in that the structure of the expression
       // is expected to line up with our column structure here.
       val refs = RasterSourceToRasterRefs(subtileDims, bandIndexes, srcs: _*) as refColNames
 

experimental/src/main/scala/org/locationtech/rasterframes/experimental/datasource/CachedDatasetRelation.scala

@@ -33,6 +33,8 @@ import org.locationtech.rasterframes.util._
  * @since 8/24/18
  */
 trait CachedDatasetRelation extends ResourceCacheSupport { self: BaseRelation ⇒
+  protected def defaultNumPartitions: Int =
+    sqlContext.sparkSession.sessionState.conf.numShufflePartitions
   protected def cacheFile: HadoopPath
   protected def constructDataset: Dataset[Row]
 

experimental/src/main/scala/org/locationtech/rasterframes/experimental/datasource/awspds/L8CatalogRelation.scala

@@ -68,7 +68,9 @@ case class L8CatalogRelation(sqlContext: SQLContext, sceneListPath: HadoopPath)
       .select(schema.map(f ⇒ col(f.name)): _*)
       .orderBy(ACQUISITION_DATE.name, PATH.name, ROW.name)
       .distinct() // The scene file contains duplicates.
-      .repartition(8, col(PATH.name), col(ROW.name))
+      .repartition(defaultNumPartitions, col(PATH.name), col(ROW.name))
+
+
   }
 }
 

experimental/src/main/scala/org/locationtech/rasterframes/experimental/datasource/awspds/MODISCatalogRelation.scala

@@ -64,7 +64,7 @@ case class MODISCatalogRelation(sqlContext: SQLContext, sceneList: HadoopPath)
         $"${GID.name}") ++ bandCols: _*
       )
       .orderBy(ACQUISITION_DATE.name, GID.name)
-      .repartition(8, col(GRANULE_ID.name))
+      .repartition(defaultNumPartitions, col(GRANULE_ID.name))
   }
 }