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https://issues.apache.org/jira/browse/SPARK-28068?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16925540#comment-16925540
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Gengliang Wang commented on SPARK-28068:
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Is this ANSI SQL? From the specification 4.16 Data analysis operations
(involving tables):
> The lead and lag functions each take three arguments, a <value expression>
> VE, an <exact numeric literal> OFFSET, and a <value expression> DEFAULT.
> `lag` second argument must be a literal
> ---------------------------------------
>
> Key: SPARK-28068
> URL: https://issues.apache.org/jira/browse/SPARK-28068
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: Dylan Guedes
> Priority: Major
>
> Currently in Spark, `lag` (and, possible, some other window functions)
> requires the 2nd argument to be a literal.
> For example, this is not allowed:
> {code:sql}
> SELECT lag(ten, four) OVER (PARTITION BY four ORDER BY ten), ten, four FROM
> tenk1 WHERE unique2 < 10;
> {code}
> However, this one works:
> {code:sql}
> SELECT lag(ten, 2) OVER (PARTITION BY four ORDER BY ten), ten, four FROM
> tenk1 WHERE unique2 < 10;
> {code}
> In comparison, Postgres accepts a literal as a 2nd argument. I found this
> issue while porting `window.sql` tests from Postgres to Spark
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