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https://issues.apache.org/jira/browse/FLINK-36123?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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lincoln lee closed FLINK-36123.
-------------------------------
Assignee: Dylan He
Resolution: Fixed
fixed in master: c749a1b61c9c154f32cb877b96274804a950bfd0
> Add PERCENTILE function
> -----------------------
>
> Key: FLINK-36123
> URL: https://issues.apache.org/jira/browse/FLINK-36123
> Project: Flink
> Issue Type: Sub-task
> Components: Table SQL / API
> Reporter: Dylan He
> Assignee: Dylan He
> Priority: Major
> Labels: pull-request-available
> Fix For: 2.0-preview
>
> Attachments: image-2024-09-06-10-23-42-094.png
>
>
> Add PERCENTILE function.
> ----
> Return a percentile value based on a continuous distribution of the input
> column. If no input row lies exactly at the desired percentile, the result is
> calculated using linear interpolation of the two nearest input values. NULL
> values are ignored in the calculation.
> Example:
> {code:sql}
> > SELECT PERCENTILE(col, 0.3) FROM VALUES (0), (10), (10) AS tab(col);
> 6.0
> > SELECT PERCENTILE(col, 0.3, freq) FROM VALUES (0, 1), (10, 2) AS tab(col,
> > freq);
> 6.0
> > SELECT PERCENTILE(col, array(0.25, 0.75)) FROM VALUES (0), (10) AS tab(col);
> [2.5,7.5]
> {code}
> Syntax:
> {code:sql}
> PERCENTILE(expr, percentage[, frequency])
> {code}
> Arguments:
> * {{expr}}: A NUMERIC expression.
> * {{percentage}}: A NUMERIC expression between 0 and 1 or an ARRAY of
> NUMERIC expressions, each between 0 and 1.
> * {{frequency}}: An optional integral number greater than 0.
> Returns:
> DOUBLE if percentage is numeric, or an ARRAY of DOUBLE if percentage is an
> ARRAY.
> Frequency describes the number of times expr must be counted. The default
> value is 1.
> See also:
> *
> [Hive|https://cwiki.apache.org/confluence/display/hive/languagemanual+udf#LanguageManualUDF-Built-inAggregateFunctions(UDAF)]
> *
> [Spark|https://spark.apache.org/docs/3.5.1/sql-ref-functions-builtin.html#mathematical-functions]
> *
> [Databricks|https://docs.databricks.com/en/sql/language-manual/functions/percentile.html]
> * [PostgreSQL|https://www.postgresql.org/docs/16/functions-aggregate.html]
> percentile_cont
> *
> [Snowflake|https://docs.snowflake.com/en/sql-reference/functions/percentile_cont]
> *
> [Oracle|https://docs.oracle.com/en/database/oracle/oracle-database/23/sqlrf/PERCENTILE_CONT.html]
> * [Wiki|https://en.wikipedia.org/wiki/Percentile]
> ----
> Currently our implementation is inspired by PERCENTILE of Spark, which offers
> an additional parameter frequency compared to SQL standard function
> PERCENTILE_CONT.
> Based on this function, we can easily extend support fo PERCENTILE_CONT and
> PERCENTILE_DISC in SQL standard with a little modification in the future.
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