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https://issues.apache.org/jira/browse/CALCITE-5955?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17768926#comment-17768926
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Oliver Lee commented on CALCITE-5955:
-------------------------------------
I'm trying to catch up on the current development and PR for this Jira ticket.
After reading the BQ docs on window functions, I do have to say that what
BigQuery syntax shows is deceivingly similar to what a "window function" is.
The docs point `percentile_cont` to window functions and meets what the window
function documentation defines as the requirement for being a window function.
It says
{quote}{{PERCENTILE_CONT (value_expression, percentile [{RESPECT | IGNORE}
NULLS])
OVER over_clause}}
{{}}
To learn more about the {{OVER}} clause and how to use it, see [Window function
calls|https://cloud.google.com/bigquery/docs/reference/standard-sql/window-function-calls].
{{...-> A window function includes an {{OVER}} clause }}
{quote}
Going off of this Oracle diagram [here
|https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/PERCENTILE_CONT.html#GUID-CA259452-A565-41B3-A4F4-DD74B66CEDE0]I
can also see Julians point about it not being a window function, it just
happens to swap out the words {{WITHIN GROUP}} with {{OVER}}
> BigQuery PERCENTILE functions are unparsed incorrectly
> ------------------------------------------------------
>
> Key: CALCITE-5955
> URL: https://issues.apache.org/jira/browse/CALCITE-5955
> Project: Calcite
> Issue Type: Bug
> Reporter: Tanner Clary
> Assignee: Tanner Clary
> Priority: Major
> Labels: pull-request-available
>
> Currently if you have a query like:
> {{SELECT PERCENTILE_CONT(x, .5) OVER() FROM x;}} the {{OVER()}} clause gets
> unparsed with a {{window frame clause}} which BigQuery defines
> [here|https://cloud.google.com/bigquery/docs/reference/standard-sql/window-function-calls#def_window_frame].
>
> From the docs: "Only aggregate analytic functions can use a window frame
> clause."
> This causes BigQuery to fail with the following error: {{Window framing
> clause is not allowed for analytic function percentile_cont}}
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