[jira] [Commented] (FLINK-8169) Document timestamp and timezone behavior for Table API & SQL

["sunjincheng (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-8169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16305527#comment-16305527 ] 

sunjincheng commented on FLINK-8169:
------------------------------------

Hi [~twalthr]  +1 to clear the processing of timezone in the flink.

Time zones not only affect Watermark, but also affect a large number of scalar function, such as DATE_FORMAT, TIMESTAMP, etc.

The calcite community is also gradually improving the processing of the time zone, such as  https://issues.apache.org/jira/browse/CALCITE-1947, So thanks for open this issue, And discuss in this issue.  

I think flink can be deployed in many country, i.e. flink well run in many timezone. Out of friendliness to the user，May be we can add a global query configuration item for timezne, e.g. in china's user can set UTC +8  as default timezone. 

What do you think? :)

Best, jincheng

> Document timestamp and timezone behavior for Table API & SQL
> ------------------------------------------------------------
>
>                 Key: FLINK-8169
>                 URL: https://issues.apache.org/jira/browse/FLINK-8169
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>            Reporter: Timo Walther
>
> {{java.sql.Date}}, {{java.sql.Time}}, and {{java.sql.Timestamp}} are timezone dependent. However, in Flink's Table & SQL API we remove this dependency and work with UTC timestamps internally. It should be documented how windows use the timestamps in different timezones for event-time. The behavior for processing-time should be explained as well. What is the result if I cast both timestamps to Long, String, or output them to a DataSet/DataStream?



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