From 5e050ea85eec9e662e5b7b49f483f3de32913931 Mon Sep 17 00:00:00 2001
From: Max Gekk <max.gekk@gmail.com>
Date: Sat, 30 May 2020 13:38:02 +0300
Subject: [PATCH] Use FAST_DATE_FORMAT as legacy frac formatter

---
 .../spark/sql/catalyst/util/TimestampFormatter.scala       | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TimestampFormatter.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TimestampFormatter.scala
index 8428964d45707..3e302e2170390 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TimestampFormatter.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TimestampFormatter.scala
@@ -121,6 +121,7 @@ class FractionTimestampFormatter(zoneId: ZoneId)
     TimestampFormatter.defaultPattern,
     zoneId,
     TimestampFormatter.defaultLocale,
+    LegacyDateFormats.FAST_DATE_FORMAT,
     needVarLengthSecondFraction = false) {
 
   @transient
@@ -224,7 +225,11 @@ class LegacyFastTimestampFormatter(
   }
 
   override def format(ts: Timestamp): String = {
-    format(fromJavaTimestamp(ts))
+    if (ts.getNanos == 0) {
+      fastDateFormat.format(ts)
+    } else {
+      format(fromJavaTimestamp(ts))
+    }
   }
 
   override def format(instant: Instant): String = {