DRILL-1132: WriterPrel should not care about collation trait of the child.

1 files changed, 6 insertions, 5 deletions

diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/WriterPrule.java b/exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/WriterPrule.java
index 15d94fb03..f3057e636 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/WriterPrule.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/WriterPrule.java
@@ -21,13 +21,10 @@ import org.apache.drill.exec.planner.common.DrillWriterRelBase;
 import org.apache.drill.exec.planner.logical.DrillRel;
 import org.apache.drill.exec.planner.logical.DrillWriterRel;
 import org.apache.drill.exec.planner.logical.RelOptHelper;
-import org.eigenbase.rel.RelCollation;
-import org.eigenbase.rel.RelCollationTraitDef;
 import org.eigenbase.rel.RelNode;
 import org.eigenbase.relopt.RelOptRule;
 import org.eigenbase.relopt.RelOptRuleCall;
 import org.eigenbase.relopt.RelTraitSet;
-import org.eigenbase.relopt.volcano.RelSubset;
 
 public class WriterPrule extends Prule{
   public static final RelOptRule INSTANCE = new WriterPrule();
@@ -62,10 +59,14 @@ public class WriterPrule extends Prule{
     @Override
     public RelNode convertChild(DrillWriterRelBase writer, RelNode rel) throws RuntimeException {
       DrillDistributionTrait childDist = rel.getTraitSet().getTrait(DrillDistributionTraitDef.INSTANCE);
-      RelCollation childCollation = rel.getTraitSet().getTrait(RelCollationTraitDef.INSTANCE);
 
+      // Create the Writer with the child's distribution because the degree of parallelism for the writer 
+      // should correspond to the number of child minor fragments. The Writer itself is not concerned with 
+      // the collation of the child.  Note that the Writer's output RowType consists of 
+      // {fragment_id varchar(255), number_of_records_written bigint} which are very different from the 
+      // child's output RowType. 
       return new WriterPrel(writer.getCluster(),
-          writer.getTraitSet().plus(childDist).plus(childCollation).plus(Prel.DRILL_PHYSICAL),
+          writer.getTraitSet().plus(childDist).plus(Prel.DRILL_PHYSICAL),
           rel, writer.getCreateTableEntry());
     }