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https://issues.apache.org/jira/browse/CALCITE-6045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17775977#comment-17775977
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Julian Hyde commented on CALCITE-6045:
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I think that Calcite's {{CURRENT_TIMESTAMP}} function should have type
{{TIMESTAMP WITH LOCAL TIME ZONE}}, which means that (after type alias
translation) it will have the requisite type for BigQuery (what BigQuery calls
{{TIMESTAMP}}). (That is a change to current behavior, and a departure from the
ISO standard, but still the best type, in my opinion.)
If people want a {{TIMESTAMP}} (what BigQuery calls {{DATETIME}}) they can call
{{LOCALTIMESTAMP}}, whose behavior will be unchanged.
> 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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