From e69dffc6f3ea752b8a3a7a3035317598e9280750 Mon Sep 17 00:00:00 2001
From: Denis Khalikov <dennis.khalikov@gmail.com>
Date: Mon, 17 Jun 2024 16:58:11 +0300
Subject: [PATCH] MCOL-5237 Proper handle DATETIME column for "ifnull"
 function. (#3201)

---
 .../columnstore/bugfixes/mcol-5237.result     | 16 ++++++++++++
 .../columnstore/bugfixes/mcol-5237.test       | 26 +++++++++++++++++++
 utils/funcexp/func_ifnull.cpp                 | 10 ++++++-
 3 files changed, 51 insertions(+), 1 deletion(-)
 create mode 100644 mysql-test/columnstore/bugfixes/mcol-5237.result
 create mode 100644 mysql-test/columnstore/bugfixes/mcol-5237.test

diff --git a/mysql-test/columnstore/bugfixes/mcol-5237.result b/mysql-test/columnstore/bugfixes/mcol-5237.result
new file mode 100644
index 000000000..89741efac
--- /dev/null
+++ b/mysql-test/columnstore/bugfixes/mcol-5237.result
@@ -0,0 +1,16 @@
+DROP DATABASE IF EXISTS mcol_5237;
+CREATE DATABASE mcol_5237;
+USE mcol_5237;
+create table t1 (a varchar(1000), b datetime, c int) ENGINE=Columnstore DEFAULT CHARSET=utf8;
+insert into t1 values
+('abc', null, 1),
+('xyz', str_to_date('2022-09-22 00:00:00', '%Y-%m-%d %H:%i:%s'), 1);
+create view v1 as
+select a, NVL(b, str_to_date('1970-01-01 00:00:00', '%Y-%m-%d %H:%i:%s')) as b, c from t1;
+select count(*) from v1 where YEAR(b) = 2022;
+count(*)
+1
+select count(*) from v1 where YEAR(b) = 1970;
+count(*)
+1
+DROP DATABASE mcol_5237;
diff --git a/mysql-test/columnstore/bugfixes/mcol-5237.test b/mysql-test/columnstore/bugfixes/mcol-5237.test
new file mode 100644
index 000000000..05e3458d4
--- /dev/null
+++ b/mysql-test/columnstore/bugfixes/mcol-5237.test
@@ -0,0 +1,26 @@
+#
+# MCOL-5237
+#
+
+--source ../include/have_columnstore.inc
+
+--disable_warnings
+DROP DATABASE IF EXISTS mcol_5237;
+--enable_warnings
+CREATE DATABASE mcol_5237;
+USE mcol_5237;
+create table t1 (a varchar(1000), b datetime, c int) ENGINE=Columnstore DEFAULT CHARSET=utf8;
+
+insert into t1 values
+('abc', null, 1),
+('xyz', str_to_date('2022-09-22 00:00:00', '%Y-%m-%d %H:%i:%s'), 1);
+
+create view v1 as
+select a, NVL(b, str_to_date('1970-01-01 00:00:00', '%Y-%m-%d %H:%i:%s')) as b, c from t1;
+
+select count(*) from v1 where YEAR(b) = 2022;
+select count(*) from v1 where YEAR(b) = 1970;
+
+--disable_warnings
+DROP DATABASE mcol_5237;
+--enable_warnings
diff --git a/utils/funcexp/func_ifnull.cpp b/utils/funcexp/func_ifnull.cpp
index 7cb5ebebc..2dcb67736 100644
--- a/utils/funcexp/func_ifnull.cpp
+++ b/utils/funcexp/func_ifnull.cpp
@@ -25,6 +25,7 @@
 #include <string>
 using namespace std;
 
+#include "constantcolumn.h"
 #include "functor_all.h"
 #include "functioncolumn.h"
 using namespace execplan;
@@ -60,7 +61,14 @@ int64_t Func_ifnull::getIntVal(Row& row, FunctionParm& parm, bool& isNull, Calpo
   if (isNull)
   {
     isNull = false;
-    return parm[1]->data()->getIntVal(row, isNull);
+    r = parm[1]->data()->getIntVal(row, isNull);
+    // MCOL-5237 In case we substitude a null value for `DATETIME` column with a value from `ConstantColumn`
+    // we have to convert the value into the `DATETIME` format for `int64_t` type.
+    if (parm[0]->data()->resultType().colDataType == CalpontSystemCatalog::DATETIME &&
+        dynamic_cast<ConstantColumn*>(parm[1]->data()))
+    {
+      r = r << 48;
+    }
   }
 
   return r;