feat(query): migrate real time functions to v2.

docs/doc/30-reference/20-functions/30-datetime-functions/now.md

@@ -12,15 +12,15 @@ NOW()
 
 ## Return Type
 
-Datetime object, returns date and time in “YYYY-MM-DD hh:mm:ss” format.
+Datetime object, returns date and time in “YYYY-MM-DD hh:mm:ss.ffffff” format.
 
 ## Examples
 
 ```sql
 SELECT NOW();
-+---------------------+
-| NOW()               |
-+---------------------+
-| 2021-09-03 01:26:07 |
-+---------------------+
++----------------------------+
+| NOW()                      |
++----------------------------+
+| 2022-10-17 08:13:58.751449 |
++----------------------------+
 ```

src/query/expression/src/date_helper.rs

@@ -19,6 +19,7 @@ use chrono::Duration;
 use chrono::NaiveDate;
 use chrono::NaiveDateTime;
 use chrono::TimeZone;
+use chrono::Utc;
 use chrono_tz::Tz;
 use num_traits::AsPrimitive;
 
@@ -161,3 +162,11 @@ impl AddTimesImpl {
         check_timestamp(ts.wrapping_add(delta.as_() * factor * 1_000_000))
     }
 }
+
+#[inline]
+pub fn today_date() -> i32 {
+    let now = Utc::now();
+    NaiveDate::from_ymd(now.year(), now.month(), now.day())
+        .signed_duration_since(NaiveDate::from_ymd(1970, 1, 1))
+        .num_days() as i32
+}

src/query/functions-v2/src/scalars/datetime.rs

@@ -13,7 +13,9 @@
 // limitations under the License.
 
 use chrono::Datelike;
+use chrono::Utc;
 use common_arrow::arrow::temporal_conversions::EPOCH_DAYS_FROM_CE;
+use common_expression::date_helper::today_date;
 use common_expression::date_helper::AddDaysImpl;
 use common_expression::date_helper::AddMonthsImpl;
 use common_expression::date_helper::AddTimesImpl;
@@ -41,13 +43,15 @@ use common_expression::vectorize_with_builder_1_arg;
 use common_expression::vectorize_with_builder_2_arg;
 use common_expression::FunctionProperty;
 use common_expression::FunctionRegistry;
+use common_expression::Value;
 use num_traits::AsPrimitive;
 
 pub fn register(registry: &mut FunctionRegistry) {
     register_cast_functions(registry);
     register_try_cast_functions(registry);
     register_add_functions(registry);
     register_sub_functions(registry);
+    register_real_time_functions(registry);
 }
 
 fn number_domain_to_timestamp_domain<T: AsPrimitive<i64>>(
@@ -401,3 +405,33 @@ macro_rules! impl_register_arith_functions {
 
 impl_register_arith_functions!(register_add_functions, "add", unsigned_ident);
 impl_register_arith_functions!(register_sub_functions, "subtract", signed_ident);
+
+fn register_real_time_functions(registry: &mut FunctionRegistry) {
+    registry.register_0_arg_core::<TimestampType, _, _>(
+        "now",
+        FunctionProperty::default(),
+        || None,
+        |_| Ok(Value::Scalar(Utc::now().timestamp_micros())),
+    );
+
+    registry.register_0_arg_core::<DateType, _, _>(
+        "today",
+        FunctionProperty::default(),
+        || None,
+        |_| Ok(Value::Scalar(today_date())),
+    );
+
+    registry.register_0_arg_core::<DateType, _, _>(
+        "yesterday",
+        FunctionProperty::default(),
+        || None,
+        |_| Ok(Value::Scalar(today_date() - 1)),
+    );
+
+    registry.register_0_arg_core::<DateType, _, _>(
+        "tomorrow",
+        FunctionProperty::default(),
+        || None,
+        |_| Ok(Value::Scalar(today_date() + 1)),
+    );
+}