update docs and comments

docs/sql-data-sources-csv.md

@@ -168,6 +168,12 @@ Data source options of CSV can be set via:
     <td>Sets the string that indicates a timestamp without timezone format. Custom date formats follow the formats at <a href="https://spark.apache.org/docs/latest/sql-ref-datetime-pattern.html">Datetime Patterns</a>. This applies to timestamp without timezone type, note that zone-offset and time-zone components are not supported when writing or reading this data type.</td>
     <td>read/write</td>
   </tr>
+  <tr>
+    <td><code>enableDateTimeParsingFallback</code></td>
+    <td>Enabled if the time parser policy is legacy or no custom date or timestamp pattern was provided</td>
+    <td>Allows to fall back to the backward compatible (Spark 1.x and 2.0) behavior of parsing dates and timestamps if values do not match the set patterns.</td>
+    <td>read</td>
+  </tr>
   <tr>
     <td><code>maxColumns</code></td>
     <td>20480</td>

docs/sql-data-sources-json.md

@@ -202,6 +202,12 @@ Data source options of JSON can be set via:
     <td>Sets the string that indicates a timestamp without timezone format. Custom date formats follow the formats at <a href="https://spark.apache.org/docs/latest/sql-ref-datetime-pattern.html">Datetime Patterns</a>. This applies to timestamp without timezone type, note that zone-offset and time-zone components are not supported when writing or reading this data type.</td>
     <td>read/write</td>
   </tr>
+  <tr>
+    <td><code>enableDateTimeParsingFallback</code></td>
+    <td>Enabled if the time parser policy is legacy or no custom date or timestamp pattern was provided</td>
+    <td>Allows to fall back to the backward compatible (Spark 1.x and 2.0) behavior of parsing dates and timestamps if values do not match the set patterns.</td>
+    <td>read</td>
+  </tr>
   <tr>
     <td><code>multiLine</code></td>
     <td><code>false</code></td>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/csv/CSVOptions.scala

@@ -175,7 +175,8 @@ class CSVOptions(
   //
   // If enabled and the date cannot be parsed, we will fall back to `DateTimeUtils.stringToDate`.
   // If enabled and the timestamp cannot be parsed, `DateTimeUtils.stringToTimestamp` will be used.
-  // Otherwise, depending on the parser policy and a custom pattern, an exception may be thrown.
+  // Otherwise, depending on the parser policy and a custom pattern, an exception may be thrown and
+  // the value will be parsed as null.
   val enableDateTimeParsingFallback: Option[Boolean] =
     parameters.get("enableDateTimeParsingFallback").map(_.toBoolean)
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/json/JSONOptions.scala

@@ -117,7 +117,8 @@ private[sql] class JSONOptions(
   //
   // If enabled and the date cannot be parsed, we will fall back to `DateTimeUtils.stringToDate`.
   // If enabled and the timestamp cannot be parsed, `DateTimeUtils.stringToTimestamp` will be used.
-  // Otherwise, depending on the parser policy and a custom pattern, an exception may be thrown.
+  // Otherwise, depending on the parser policy and a custom pattern, an exception may be thrown and
+  // the value will be parsed as null.
   val enableDateTimeParsingFallback: Option[Boolean] =
     parameters.get("enableDateTimeParsingFallback").map(_.toBoolean)