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https://issues.apache.org/jira/browse/CALCITE-6045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17774265#comment-17774265
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Julian Hyde commented on CALCITE-6045:
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This all sounds right. I have been feeling guilty for several years that
{{CURRENT_TIMESTAMP}} returns a {{TIMESTAMP}} rather than the {{TIMESTAMP WITH
TIME ZONE}} as required by the SQL standard.
We should fix it, but it will be a breaking change. Also, do you think the
{{TIMESTAMP WITH TIME ZONE}} data type is in good enough shape to support it?
Note that there is also {{LOCAL_TIMESTAMP}}, which I believe is of type
{{TIMESTAMP}} and is in the session time zone. I believe that its type and
value are correct.
Should we add a new function that returns a {{TIMESTAMP WITH LOCAL TIME ZONE}}?
> CURRENT_TIMESTAMP has incorrect return type
> -------------------------------------------
>
> Key: CALCITE-6045
> URL: https://issues.apache.org/jira/browse/CALCITE-6045
> Project: Calcite
> Issue Type: Bug
> Reporter: Tanner Clary
> Priority: Major
>
> When trying to work on CALCITE-6021, I noticed that {{CURRENT_TIMESTAMP}}
> currently returns type {{TIMESTAMP}} when it should be
> {{TIMESTAMP_WITH_LOCAL_TIME_ZONE}}.
> After modifying it, I noticed function was returning the time from (UTC -
> System TZ) hours ago. For example, I am in {{America/Los_Angeles}} and if I
> called the function at {{2023-10-10 13:28:00 America/Los_Angeles}}, it would
> return {{2023-10-10 06:28:00 America/Los_Angeles}}.
> I think this is because the DataContext {{CURRENT_TIMESTAMP}} variable, which
> is meant to represent milliseconds since epoch UTC, actually has the timezone
> offset applied in {{CalciteConnectionImpl#DataContextImpl}}
> [here|https://github.com/apache/calcite/blob/main/core/src/main/java/org/apache/calcite/jdbc/CalciteConnectionImpl.java#L442].
> To be clear: it is meant to represent millis since epoch UTC, but instead it
> is millis since epoch [system tz], as I understand it.
> Additionally, I believe the {{getString()}} method for timestamps in
> AvaticaResultSet should behave similarly to
> [{{SqlFunctions#timestampWithLocalTimezoneToString()}}|https://github.com/apache/calcite/blob/main/core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java#L4021]
> when dealing with a {{TIMESTAMP WITH LOCAL TIME ZONE}}. Right now, it does
> not take the timezone into consideration so although it represents the
> accurate instant in time, it displays differently than
> {{CAST(CURRENT_TIMESTAMP AS VARCHAR)}}.
> For example, {{SELECT CURRENT_TIMESTAMP, CAST(CURRENT_TIMESTAMP AS
> VARCHAR)}}, with the correct return type, returns something like:
> {{2023-10-10 13:28:00 | 2023-10-10 06:28:00.000 America/Los_Angeles}}
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