Add utc_timestamp function (#1456)

be/src/exprs/timestamp_functions.cpp

@@ -243,6 +243,18 @@ DateTimeVal TimestampFunctions::curtime(FunctionContext* context) {
     return return_val;
 }
 
+DateTimeVal TimestampFunctions::utc_timestamp(FunctionContext* context) {
+    TimeInterval interval;
+    // TODO(liuhy): we only support Beijing Timezone, so minus 28800
+    interval.second = -28800;
+    DateTimeValue dtv = *(context->impl()->state()->now());
+    dtv.date_add_interval(interval, SECOND);
+    
+    DateTimeVal return_val;
+    dtv.to_datetime_val(&return_val);
+    return return_val;
+}
+
 DateTimeVal TimestampFunctions::to_date(
         FunctionContext* ctx, const DateTimeVal& ts_val) {
     if (ts_val.is_null) {

be/src/exprs/timestamp_functions.h

@@ -78,6 +78,7 @@ public:
     // Date/time functions.
     static doris_udf::DateTimeVal now(doris_udf::FunctionContext* context);
     static doris_udf::DateTimeVal curtime(doris_udf::FunctionContext* context);
+    static doris_udf::DateTimeVal utc_timestamp(doris_udf::FunctionContext* context);
     static doris_udf::DateTimeVal to_date(
         doris_udf::FunctionContext* ctx, const doris_udf::DateTimeVal& ts_val);
     static doris_udf::IntVal date_diff(

docs/documentation/cn/sql-reference/sql-functions/date-time-functions/utc_timestamp.md

@@ -0,0 +1,24 @@
+# utc_timestamp
+
+## Syntax
+
+`DATETIME UTC_TIMESTAMP()`
+
+## Description
+
+返回当前UTC日期和时间在 "YYYY-MM-DD HH:MM:SS" 或
+
+"YYYYMMDDHHMMSS"格式的一个值
+
+根据该函数是否用在字符串或数字语境中
+
+## Examples
+
+```
+mysql> select utc_timestamp(),utc_timestamp() + 1;
++---------------------+---------------------+
+| utc_timestamp()     | utc_timestamp() + 1 |
++---------------------+---------------------+
+| 2019-07-10 12:31:18 |      20190710123119 |
++---------------------+---------------------+
+```

gensrc/script/doris_builtins_functions.py

@@ -112,6 +112,8 @@ visible_functions = [
         '_ZN5doris18TimestampFunctions3nowEPN9doris_udf15FunctionContextE'],
     [['curtime', 'current_time'], 'DATETIME', [],
         '_ZN5doris18TimestampFunctions7curtimeEPN9doris_udf15FunctionContextE'],
+    [['utc_timestamp'], 'DATETIME', [],
+        '_ZN5doris18TimestampFunctions13utc_timestampEPN9doris_udf15FunctionContextE'],
     [['timestamp'], 'DATETIME', ['DATETIME'],
         '_ZN5doris18TimestampFunctions9timestampEPN9doris_udf15FunctionContextERKNS1_11DateTimeValE'],