Adding CONVERT_TZ and DATETIME functions to SQL and PPL

[MitchellGale]

Description

PR adds support for convert_tz and Datetime for PPL and SQL languages.

convert_tz

Syntax for convert_tz:
convert_tz(datetime string, from timezone, to timezone)
It converts the datetime string from the from timezone to the to timezone. Converts from negative to positive timezone, from positive to negative, from positive to positive or negative to negative time zones. Works across year roll-over and leap years.
Example:

opensearchsql> SELECT convert_tz('2021-05-12 00:00:00','-12:00','+13:00'); 
fetched rows / total rows = 1/1
+-------------------------------------------------------+
| convert_tz('2021-05-12 00:00:00','-12:00','+13:00')   |
|-------------------------------------------------------|
| 2021-05-13 01:00:00                                   |
+-------------------------------------------------------+

opensearchsql> SELECT convert_tz('2021-05-12 12:34:56','-00:00','+01:00');
fetched rows / total rows = 1/1
+-------------------------------------------------------+
| convert_tz('2021-05-12 12:34:56','-00:00','+01:00')   |
|-------------------------------------------------------|
| 2021-05-12 13:34:56                                   |
+-------------------------------------------------------+

nulls

It returns null for time zones outside of the allowed range (allow range is -13:59 -> +14:00)

opensearchsql> SELECT convert_tz('2021-05-12 12:34:56','-00:00','+15:00');
fetched rows / total rows = 1/1
+-------------------------------------------------------+
| convert_tz('2021-05-12 12:34:56','-00:00','+14:01')   |
|-------------------------------------------------------|
| null                                                  |
+-------------------------------------------------------+

opensearchsql> SELECT convert_tz('2021-05-12 12:34:56','-13:00','+10:00');
fetched rows / total rows = 1/1
+-------------------------------------------------------+
| convert_tz('2021-05-12 12:34:56','-14:00','+10:00')   |
|-------------------------------------------------------|
| null                                                  |
+-------------------------------------------------------+

Leap year

opensearchsql> SELECT convert_tz('2005-02-28 20:00:00','-10:00','+10:00');
fetched rows / total rows = 1/1
+-------------------------------------------------------+
| convert_tz('2005-02-28 20:00:00','-10:00','+10:00')   |
|-------------------------------------------------------|
| 2005-03-01 16:00:00                                   |
+-------------------------------------------------------+

opensearchsql> SELECT convert_tz('2004-02-28 20:00:00','-10:00','+10:00');
fetched rows / total rows = 1/1
+-------------------------------------------------------+
| convert_tz('2004-02-28 20:00:00','-10:00','+10:00')   |
|-------------------------------------------------------|
| 2004-02-29 16:00:00                                   |
+-------------------------------------------------------+

DateTime

DATETIME(timestamp_expression [, time_zone])

fetched rows / total rows = 1/1
+---------------------------------------------------+
| DATETIME('2008-12-25 05:30:00-05:00', '+05:00')   |
|---------------------------------------------------|
| 2008-12-25 15:30:00                               |
+---------------------------------------------------+

opensearchsql> SELECT DATETIME('2008-12-25 05:30:00', '+05:00');
fetched rows / total rows = 1/1
+---------------------------------------------+
| DATETIME('2008-12-25 05:30:00', '+05:00')   |
|---------------------------------------------|
| 2008-12-25 10:30:00                         |
+---------------------------------------------+

opensearchsql> SELECT DATETIME('2008-12-25 05:30:00+10:00'); 
fetched rows / total rows = 1/1
+-----------------------------------------+
| DATETIME('2008-12-25 05:30:00+10:00')   |
|-----------------------------------------|
| 2008-12-25 05:30:00                     |
+-----------------------------------------+

opensearchsql> SELECT DATETIME('2008-12-25 05:30:00');
fetched rows / total rows = 1/1
+-----------------------------------+
| DATETIME('2008-12-25 05:30:00')   |
|-----------------------------------|
| 2008-12-25 05:30:00               |
+-----------------------------------+

Issues Resolved

#703
#46

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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For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[dai-chen]

Could you point me to the documentation for DATETIME function? For some reason I didn't find it in MySQL...

[MitchellGale]

@dai-chen DATETIME doesn't exist in MySQL, but it's implemented like a constructor, similar to the TIMESTATMP but for datetime.
Also listed here #722.

[dai-chen]

LGTM. Thanks for the changes!