[jira] [Created] (IGNITE-19371) Sql. Provide support for the TIME_WITH_LOCAL_TIME_ZONE and TIMESTAMP_WITH_LOCAL_TIME_ZONE data types.

["Pavel Pereslegin (Jira)" <ji...@apache.org>]

Pavel Pereslegin created IGNITE-19371:
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             Summary: Sql. Provide support for the TIME_WITH_LOCAL_TIME_ZONE and TIMESTAMP_WITH_LOCAL_TIME_ZONE data types.
                 Key: IGNITE-19371
                 URL: https://issues.apache.org/jira/browse/IGNITE-19371
             Project: Ignite
          Issue Type: Improvement
            Reporter: Pavel Pereslegin


Apache Calcite supports the following "timezone aware" datatypes.

* TIMESTAMP WITH LOCAL TIME ZONE
* TIME WITH LOCAL TIME ZONE

The implementation is similar to Oracle "TIMESTAMP WITH LOCAL TIME ZONE" and PostgreSQL "TIMESTAMP WITH TIME ZONE".

From Oracle documentation:
"The TIMESTAMP WITH LOCAL TIME ZONE data type is a variant of TIMESTAMP that includes a time zone offset in its value. Data stored in the database is normalized to the database time zone (UTC) and time zone offset is not stored as part of the column data. "

The issue described in the task is one of the problems in terms of supporting work with the client's timezone.

Currently we have the following types:
||Calcite type||JDBC Type||Current Ignite type||Type contains timezone info||
|TIME|java.sql.Time|java.time.LocalTime|no|
|TIME_WITH_LOCAL_TIME_ZONE|java.sql.Time|java.time.LocalTime|no|
|TIMESTAMP|java.sql.Timestamp|java.time.LocalDateTime|no|
|TIMESTAMP_WITH_LOCAL_TIME_ZONE|java.sql.Timestamp|java.time.Instant|yea|

 

*_WITH_LOCAL_TIME_ZONE types must take into account the client's local time zone. Those. if the client is in the "GMT+3" time zone and is passing the value "14:00", the value must be converted from GMT+3 to UTC and the value "11:00" must be stored in the database.

Currently we do not take into account the client's/initiator's timezone in any way.
h2. Proposal.

There are two implementation options, it all depends on when we will transfer the client's time zone.
h2. 1. Transfer TimeZone from client per connection.

 In this case the timezone from client will be stored per connection.
{code:java}
 connect()
   // save client's time zone to context/session
   
 insert (time with local time zone '14:00')
   // store: value - timezone_offset = '11:00' (UTC)
   
 select time with local time zone
   // read: value from DB '11:00' UTC
   // transfer: value + timezone_offset
   // returns: LocalTime
   
 getTime()
   // return value{code}
In this case all offsets will be applied on the server side, those timestamp_with_time_zone we'll need to be LocalDateTime.
Since the timezone will only be set for each connection. Changing the client's time zone during connection will have no effect.
E,g,
{code:java}
set timeZone='GMT+1'
connect()
insert (time with local time zone '14:00') // db stores '13:00'
select time -> returns '14:00'
set timeZone='GMT+2'
select time -> returns '14:00'
reconnect()
select time -> returns '15:00'{code}
As a result we'll have the following data types.
||Calcite type||JDBC Type||Current Ignite type||Type contains timezone info||
|TIME|java.sql.Time|java.time.LocalTime|no|
|TIME_WITH_LOCAL_TIME_ZONE|java.sql.Time|java.time.LocalTime|no|
|TIMESTAMP|java.sql.Timestamp|java.time.LocalDateTime|no|
|TIMESTAMP_WITH_LOCAL_TIME_ZONE|java.sql.Timestamp|java.time.LocalDateTime|no|
h2. 2. Transfer TimeZone from client per query.

In this case, we will need to add some special type instead of LocalTime because it does not store timezone information.
Since we will have time zone information on the client, we will simply translate the value to the local ghb time zone when it is displayed.
 
Those. the scheme of work is approximately the following.
{code:java}
 connect()
 
 insert (time with local time zone '14:00')
   // put client's timezone from the request to execution context.
   // store: value - timezone_offset = '11:00' (UTC)
 
 select time with local time zone
   // read: value from DB '11:00' UTC
   // returns: LocalTimeTz
   
 getTime()
   // if (value instanceof LocalTimeTz)
   //    read UTC '11:00' + local_timezone_offset{code}
 But usually no one does this, the time zone is transmitted when connected to the server.
 And we need to separately discover how it will work with a Ignite thin client.



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