feat(query): function about convert_timezone #16177

[florann]

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Summary

The goal was to add a function that allow to convert a timestamp, with a timezone or not, to a specific timezone

• fixes: Feature: function about convert_timezone #16177

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test

Type of change

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe):

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This change is 

[b41sh]

Hi @florann
Thanks for your contribution, please add the convert_timezone function at this file https://github.com/datafuselabs/databend/blob/main/src/query/functions/src/scalars/datetime.rs
and add some unit tests for it https://github.com/datafuselabs/databend/tree/main/src/query/functions/tests/it/scalars/datetime.rs

[florann]

Hello !

@b41sh, I correct all the points you previously mentioned.

:^)

I'll try to watch a bit in depth how unit test configuration is working otherwise I'll ask for your help

[florann]

Okay, so I really don't get how I need to set up my unit test.
Even refering to the function to_timestamp isn't helping me

[b41sh]

The arguments are in the wrong order. They should be src_timezone, target_timezone, source_timestamp

[TCeason]

Yes.

Need support

CONVERT_TIMEZONE( <source_tz> , <target_tz> , <source_timestamp_ntz> )

and

CONVERT_TIMEZONE( <target_tz> , <source_timestamp> )

[b41sh]

ditto

[b41sh]

check validity here to handle NULL value

            if let Some(validity) = &ctx.validity {
                if !validity.get_bit(output.len()) {
                    output.push_default();
                    return;
                }
            }

[TCeason]

Please add test in https://github.com/datafuselabs/databend/blob/main/tests/sqllogictests/suites/query/functions/02_0012_function_datetimes_tz.test

[TCeason]

I think no need to create dummy timezone. You can use this https://docs.rs/chrono/latest/chrono/offset/trait.TimeZone.html#method.timestamp_opt to convert ts to source timezone.

Then convert the ts with src tz to target tz.

[TCeason]

e.g. https://github.com/datafuselabs/databend/blob/78d41aedc7f078485ee4ada10281d9f81a09caa5/src/common/io/src/cursor_ext/cursor_read_datetime_ext.rs#L194

[TCeason]

timestamp_micros()

[TCeason]

Cool.

SELECT CONVERT_TIMEZONE(
'America/Los_Angeles',
'America/New_York',
to_timestamp('2024-01-01 14:00:00')
) AS conv;

SELECT CONVERT_TIMEZONE(
'Europe/Warsaw',
'UTC',
'2024-01-01 00:00:00'::TIMESTAMP
) AS conv;

SELECT CONVERT_TIMEZONE(
'America/Los_Angeles',
'2024-04-05 12:00:00 +02:00'::TIMESTAMP
) AS time_in_la;

SELECT
CURRENT_TIMESTAMP() AS now_in_la,
CONVERT_TIMEZONE('America/New_York', CURRENT_TIMESTAMP()) AS now_in_nyc,
CONVERT_TIMEZONE('Europe/Paris', CURRENT_TIMESTAMP()) AS now_in_paris,
CONVERT_TIMEZONE('Asia/Tokyo', CURRENT_TIMESTAMP()) AS now_in_tokyo;

Need to add these tests in logical test.