Casting timestamps

Results of applications that cast numerics to timestamps differ from Hive 2 to Hive 3. Apache Hive changed the behavior of CAST to comply with the SQL Standard, which does not associate a time zone with the TIMESTAMP type.

Before Upgrade

Casting a numeric type value into a timestamp could be used to produce a result that reflected the time zone of the cluster. For example, 1597217764557 is 2020-08-12 00:36:04 PDT. Running the following query casts the numeric to a timestamp in PDT:

> SELECT CAST(1597217764557 AS TIMESTAMP); 
| 2020-08-12 00:36:04 |

After Upgrade

Casting a numeric type value into a timestamp produces a result that reflects the UTC instead of the time zone of the cluster. Running the following query casts the numeric to a timestamp in UTC.

> SELECT CAST(1597217764557 AS TIMESTAMP); 
| 2020-08-12 07:36:04.557  |

Action Required

Change applications. Do not cast from a numeral to obtain a local time zone. Built-in functions from_utc_timestamp and to_utc_timestamp can be used to mimic behavior before the upgrade.