[cherry-pick](branch-30)fix date_floor function return wrong result (#41948) (#43588)

cherry-pick from master (#41948)

Author: zhangstar333

be/src/vec/functions/function_datetime_floor_ceil.cpp

@@ -21,6 +21,7 @@
 #include <boost/iterator/iterator_facade.hpp>
 #include <cstddef>
 #include <cstdint>
+#include <cstring>
 #include <memory>
 #include <type_traits>
 #include <utility>
@@ -293,7 +294,7 @@ struct FloorCeilImpl {
                                       PaddedPODArray<NativeType>& res, NullMap& null_map) {
         // time_round(datetime,const(period))
         if (period < 1) {
-            null_map.resize_fill(dates.size(), true);
+            memset(null_map.data(), 1, sizeof(UInt8) * dates.size());
             return;
         }
         for (int i = 0; i < dates.size(); ++i) {
@@ -337,7 +338,7 @@ struct FloorCeilImpl {
                                    NativeType origin_date, PaddedPODArray<NativeType>& res,
                                    NullMap& null_map) {
         if (period < 1) {
-            null_map.resize_fill(dates.size(), true);
+            memset(null_map.data(), 1, sizeof(UInt8) * dates.size());
             return;
         }
         switch (period) {
@@ -424,7 +425,7 @@ struct FloorCeilImpl {
                                     const PaddedPODArray<NativeType>& origin_dates,
                                     PaddedPODArray<NativeType>& res, NullMap& null_map) {
         if (period < 1) {
-            null_map.resize_fill(dates.size(), true);
+            memset(null_map.data(), 1, sizeof(UInt8) * dates.size());
             return;
         }
         for (int i = 0; i < dates.size(); ++i) {

regression-test/data/correctness_p0/test_time_round.out

@@ -123,3 +123,8 @@
 2020-02-02T11:45:14
 2020-02-02T11:45:14
 
+-- !select_1 --
+2020-02-02T13:09:20	\N
+2020-02-02T13:09:20	\N
+2020-02-02T13:09:20	\N
+

regression-test/suites/correctness_p0/test_time_round.groovy

@@ -89,4 +89,5 @@ suite("test_time_round") {
     qt_select "select hour_floor(dt,2,o) from dbround order by id;"
     qt_select "select hour_floor(dt,p,'1919-08-10 11:45:14') from dbround order by id;"
     qt_select "select hour_floor(dt,2,'1919-08-10 11:45:14') from dbround order by id;"
+    qt_select_1 "select dt,hour_floor(dt,0) from dbround order by id;"
 }