From 065f5f9625030f12daa66aa096510e401bcd8e9a Mon Sep 17 00:00:00 2001
From: PHILO-HE <feilong.he@intel.com>
Date: Tue, 24 Dec 2024 17:13:56 +0800
Subject: [PATCH 1/4] Initial

---
 velox/functions/sparksql/registration/RegisterDatetime.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/velox/functions/sparksql/registration/RegisterDatetime.cpp b/velox/functions/sparksql/registration/RegisterDatetime.cpp
index 334a021457b0..e93daa887b04 100644
--- a/velox/functions/sparksql/registration/RegisterDatetime.cpp
+++ b/velox/functions/sparksql/registration/RegisterDatetime.cpp
@@ -52,6 +52,8 @@ void registerDatetimeFunctions(const std::string& prefix) {
   registerFunction<DateAddFunction, Date, Date, int8_t>({prefix + "date_add"});
   registerFunction<DateAddFunction, Date, Date, int16_t>({prefix + "date_add"});
   registerFunction<DateAddFunction, Date, Date, int32_t>({prefix + "date_add"});
+  registerFunction<FormatDateTimeFunction, Varchar, Timestamp, Varchar>(
+      {prefix + "date_format"});
   registerFunction<DateFromUnixDateFunction, Date, int32_t>(
       {prefix + "date_from_unix_date"});
   registerFunction<DateSubFunction, Date, Date, int8_t>({prefix + "date_sub"});

From 0fffe27c958c1b2ad41e74a8ed87a6604ed3646c Mon Sep 17 00:00:00 2001
From: PHILO-HE <feilong.he@intel.com>
Date: Wed, 25 Dec 2024 10:46:34 +0800
Subject: [PATCH 2/4] Add doc

---
 velox/docs/functions/spark/datetime.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/velox/docs/functions/spark/datetime.rst b/velox/docs/functions/spark/datetime.rst
index 254756aaa108..53ad6483281c 100644
--- a/velox/docs/functions/spark/datetime.rst
+++ b/velox/docs/functions/spark/datetime.rst
@@ -34,6 +34,13 @@ These functions support TIMESTAMP and DATE input types.
     deducted from ``start_date``.
     Supported types for ``num_days`` are: TINYINT, SMALLINT, INTEGER.
 
+.. spark:function:: date_format(timestamp, dateFormat) -> string
+
+    Converts `timestamp` to a string in the format specified by `dateFormat`.
+
+        SELECT date_format('2020-01-29', 'yyyy'); -- '2020'
+        SELECT date_format('2024-05-30 08:00:00', 'yyyy-MM-dd'); -- '2024-05-30'
+
 .. spark:function:: date_from_unix_date(integer) -> date
 
     Creates date from the number of days since 1970-01-01 in either direction. Returns null when input is null.

From 06a3b7e3267240facb9d2772d39f3204e0df46d0 Mon Sep 17 00:00:00 2001
From: PHILO-HE <feilong.he@intel.com>
Date: Fri, 27 Dec 2024 14:12:48 +0800
Subject: [PATCH 3/4] Update doc

---
 velox/docs/functions/spark/datetime.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/velox/docs/functions/spark/datetime.rst b/velox/docs/functions/spark/datetime.rst
index 53ad6483281c..df371441b878 100644
--- a/velox/docs/functions/spark/datetime.rst
+++ b/velox/docs/functions/spark/datetime.rst
@@ -37,6 +37,9 @@ These functions support TIMESTAMP and DATE input types.
 .. spark:function:: date_format(timestamp, dateFormat) -> string
 
     Converts `timestamp` to a string in the format specified by `dateFormat`.
+    The format follows Spark's
+    `Datetime patterns
+    <https://spark.apache.org/docs/latest/sql-ref-datetime-pattern.html>`_.
 
         SELECT date_format('2020-01-29', 'yyyy'); -- '2020'
         SELECT date_format('2024-05-30 08:00:00', 'yyyy-MM-dd'); -- '2024-05-30'

From e543f543319ac0a1386ee61a8ab1c26b6a6d3459 Mon Sep 17 00:00:00 2001
From: PHILO-HE <feilong.he@intel.com>
Date: Fri, 27 Dec 2024 15:36:05 +0800
Subject: [PATCH 4/4] Fix comment

---
 velox/docs/functions/spark/datetime.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/velox/docs/functions/spark/datetime.rst b/velox/docs/functions/spark/datetime.rst
index df371441b878..650056aee28b 100644
--- a/velox/docs/functions/spark/datetime.rst
+++ b/velox/docs/functions/spark/datetime.rst
@@ -36,7 +36,7 @@ These functions support TIMESTAMP and DATE input types.
 
 .. spark:function:: date_format(timestamp, dateFormat) -> string
 
-    Converts `timestamp` to a string in the format specified by `dateFormat`.
+    Converts ``timestamp`` to a string in the format specified by ``dateFormat``.
     The format follows Spark's
     `Datetime patterns
     <https://spark.apache.org/docs/latest/sql-ref-datetime-pattern.html>`_.