TAJO-1234: Rearrange timezone in date/time types.

[hyunsik]

See the jira (https://issues.apache.org/jira/browse/TAJO-1234). I explained there.

[hyunsik]

I've updated the patch.

[hyunsik]

This is an urgent issue. So, I would be happy if anyone reviews it as soon as possible.

[hyunsik]

I've updated the documentation.

[hyunsik]

I found that some unit tests are sensitive to local time zone. I'll update the patch soon

[hyunsik]

I've updated the patch.

[hyunsik]

Java 6 does not recognize 'UTC+9' or some location-based time zone like 'Asia/Seoul' because it has scarce time zone databases.

I fixed the problematic unit tests to use the prefix 'GMT' instead of 'UTC'.

[hyunsik]

In addition, I added the table property 'timezone'. You can use it in your CREATE TABLE statement as follows:

CREATE EXTERNAL TABLE table1 (
 t_timestamp  TIMESTAMP,
 t_time    TIME,
 t_date    DATE
) USING TEXTFILE WITH('text.delimiter'='|', 'timezone'='ASIA/Seoul') LOCATION '/path-to-table/'

It will translate timestamp and time value by a specified time zone. I also added the detailed documentation about time zone property.

[jihoonson]

How about using TajoConstants.UTC_TIMEZONE?

[blrunner]

Thanks @hyunsik

+1 for the patch.

All unit test cases finished successfully on three timezones such as Asia/Seoul, America/Toronto,Europe/Paris.

After considering @jihoonson's comment, push it. :)

[jihoonson]

@blrunner, thanks for your testing.
In my computer, unit tests failed due to another problem of my machine, so I couldn't verify the patch.
The patch looks good to me, too.

[hyunsik]

Thank you all guys for the quick review.

@jihoonson TajoConstants.UTC_TIMEZONE is used for a system default config. In contrast, the unit tests were written to test the behavior of different time zones. So, I'll change the constant name to DEFAULT_SYSTEM_TIMEZONE.

I'll commit it shortly due to unit test failure. If there are further feedback, I'll reflect them later in another jira.