Implementation of UTC_DATE, UTC_TIME, UTC_TIMESTAMP

[MitchellGale]

Description

UTC_DATE, UTC_TIME, UTC_TIMESTAMP are all implemented according to MySQL standard.

Issues Resolved

Support date and time functions for new engine · Issue #709 · opendistro-for-elasticsearch/sql

Date time query improvement · Issue #46 · opensearch-project/sql

opensearchsql> select utc_date();                                                                                                                                                  
fetched rows / total rows = 1/1
+--------------+
| utc_date()   |
|--------------|
| 2022-10-03   |
+--------------+
opensearchsql> select utc_time();                                                                                                                                                  
fetched rows / total rows = 1/1
+--------------+
| utc_time()   |
|--------------|
| 17:54:27     |
+--------------+
opensearchsql> select utc_timestamp();                                                                                                                                             
fetched rows / total rows = 1/1
+---------------------+
| utc_timestamp()     |
|---------------------|
| 2022-10-03 17:54:28 |
+---------------------+

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

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