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From r...@apache.org
Subject spark git commit: [SPARK-17494][SQL] changePrecision() on compact decimal should respect rounding mode
Date Thu, 22 Sep 2016 04:02:45 GMT
Repository: spark
Updated Branches:
  refs/heads/branch-2.0 966abd6af -> ec377e773


[SPARK-17494][SQL] changePrecision() on compact decimal should respect rounding mode

## What changes were proposed in this pull request?

Floor()/Ceil() of decimal is implemented using changePrecision() by passing a rounding mode,
but the rounding mode is not respected when the decimal is in compact mode (could fit within
a Long).

This Update the changePrecision() to respect rounding mode, which could be ROUND_FLOOR, ROUND_CEIL,
ROUND_HALF_UP, ROUND_HALF_EVEN.

## How was this patch tested?

Added regression tests.

Author: Davies Liu <davies@databricks.com>

Closes #15154 from davies/decimal_round.

(cherry picked from commit 8bde03bf9a0896ea59ceaa699df7700351a130fb)
Signed-off-by: Reynold Xin <rxin@databricks.com>


Project: http://git-wip-us.apache.org/repos/asf/spark/repo
Commit: http://git-wip-us.apache.org/repos/asf/spark/commit/ec377e77
Tree: http://git-wip-us.apache.org/repos/asf/spark/tree/ec377e77
Diff: http://git-wip-us.apache.org/repos/asf/spark/diff/ec377e77

Branch: refs/heads/branch-2.0
Commit: ec377e77307b477d20a642edcd5ad5e26b989de6
Parents: 966abd6
Author: Davies Liu <davies@databricks.com>
Authored: Wed Sep 21 21:02:30 2016 -0700
Committer: Reynold Xin <rxin@databricks.com>
Committed: Wed Sep 21 21:02:42 2016 -0700

----------------------------------------------------------------------
 .../org/apache/spark/sql/types/Decimal.scala    | 28 +++++++++++++++++---
 .../apache/spark/sql/types/DecimalSuite.scala   | 15 +++++++++++
 2 files changed, 39 insertions(+), 4 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/spark/blob/ec377e77/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
----------------------------------------------------------------------
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
index cc8175c..7085905 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
@@ -242,10 +242,30 @@ final class Decimal extends Ordered[Decimal] with Serializable {
       if (scale < _scale) {
         // Easier case: we just need to divide our scale down
         val diff = _scale - scale
-        val droppedDigits = longVal % POW_10(diff)
-        longVal /= POW_10(diff)
-        if (math.abs(droppedDigits) * 2 >= POW_10(diff)) {
-          longVal += (if (longVal < 0) -1L else 1L)
+        val pow10diff = POW_10(diff)
+        // % and / always round to 0
+        val droppedDigits = longVal % pow10diff
+        longVal /= pow10diff
+        roundMode match {
+          case ROUND_FLOOR =>
+            if (droppedDigits < 0) {
+              longVal += -1L
+            }
+          case ROUND_CEILING =>
+            if (droppedDigits > 0) {
+              longVal += 1L
+            }
+          case ROUND_HALF_UP =>
+            if (math.abs(droppedDigits) * 2 >= pow10diff) {
+              longVal += (if (droppedDigits < 0) -1L else 1L)
+            }
+          case ROUND_HALF_EVEN =>
+            val doubled = math.abs(droppedDigits) * 2
+            if (doubled > pow10diff || doubled == pow10diff && longVal % 2 !=
0) {
+              longVal += (if (droppedDigits < 0) -1L else 1L)
+            }
+          case _ =>
+            sys.error(s"Not supported rounding mode: $roundMode")
         }
       } else if (scale > _scale) {
         // We might be able to multiply longVal by a power of 10 and not overflow, but if
not,

http://git-wip-us.apache.org/repos/asf/spark/blob/ec377e77/sql/catalyst/src/test/scala/org/apache/spark/sql/types/DecimalSuite.scala
----------------------------------------------------------------------
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/types/DecimalSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/types/DecimalSuite.scala
index e1675c9..4cf329d 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/types/DecimalSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/types/DecimalSuite.scala
@@ -22,6 +22,7 @@ import scala.language.postfixOps
 import org.scalatest.PrivateMethodTester
 
 import org.apache.spark.SparkFunSuite
+import org.apache.spark.sql.types.Decimal._
 
 class DecimalSuite extends SparkFunSuite with PrivateMethodTester {
   /** Check that a Decimal has the given string representation, precision and scale */
@@ -193,4 +194,18 @@ class DecimalSuite extends SparkFunSuite with PrivateMethodTester {
     assert(new Decimal().set(100L, 10, 0).toUnscaledLong === 100L)
     assert(Decimal(Long.MaxValue, 100, 0).toUnscaledLong === Long.MaxValue)
   }
+
+  test("changePrecision() on compact decimal should respect rounding mode") {
+    Seq(ROUND_FLOOR, ROUND_CEILING, ROUND_HALF_UP, ROUND_HALF_EVEN).foreach { mode =>
+      Seq("0.4", "0.5", "0.6", "1.0", "1.1", "1.6", "2.5", "5.5").foreach { n =>
+        Seq("", "-").foreach { sign =>
+          val bd = BigDecimal(sign + n)
+          val unscaled = (bd * 10).toLongExact
+          val d = Decimal(unscaled, 8, 1)
+          assert(d.changePrecision(10, 0, mode))
+          assert(d.toString === bd.setScale(0, mode).toString(), s"num: $sign$n, mode: $mode")
+        }
+      }
+    }
+  }
 }


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