Refactor timestamp2timestamptz_opt_error()

akorotkov · akorotkov · commit a6888fde7f0d · 2019-10-21T23:07:07.000+03:00
While casting from timestamp to timestamptz we do timestamp2tm() then tm2timestamp(). This commit eliminates call to tm2timestamp(). Instead, it directly applies timezone offset to the original timestamp value. That makes upcoming datetime overflow handling in jsonpath easier. That should also save us some CPU cycles. Discussion: https://postgr.es/m/CAPpHfdvRPRh_mTGar5WmDeRZ%3DU5dOXHdxspYYD%3D76m3knNGjXA%40mail.gmail.com Author: Alexander Korotkov Reviewed-by: Tom Lane
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
@@ -5210,8 +5210,17 @@ timestamp2timestamptz_opt_error(Timestamp timestamp, bool *have_error)
 	{
 		tz = DetermineTimeZoneOffset(tm, session_timezone);
 
-		if (!tm2timestamp(tm, fsec, &tz, &result))
+		result = dt2local(timestamp, -tz);
+
+		if (IS_VALID_TIMESTAMP(result))
+		{
 			return result;
+		}
+		else if (have_error)
+		{
+			*have_error = true;
+			return (TimestampTz) 0;
+		}
 	}
 
 	if (have_error)
