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https://issues.apache.org/jira/browse/OPTIQ-337?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14053405#comment-14053405
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Julian Hyde commented on OPTIQ-337:
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I don't have a strong opinion about {{supportsIgnoreNull}}, but my advice is to
write tests for the most important ones (e.g. whether {{COUNT(c) OVER w IGNORE
NULLS}} is supposed to work, or throw, or silently ignore), make sure they pass
before check-in, and leave it at that. The less important cases can be dealt
with as separate jiras.
> Support IGNORE NULLS in window aggregates
> -----------------------------------------
>
> Key: OPTIQ-337
> URL: https://issues.apache.org/jira/browse/OPTIQ-337
> Project: Optiq
> Issue Type: Improvement
> Reporter: Vladimir Sitnikov
> Assignee: Julian Hyde
>
> Some of the functions are a bit more useful when they support IGNORE/RESPECT
> NULLS clause.
> For instance, FIRST_VALUE, LAST_VALUE, LEAD, LAG run in RESPECT NULLS by
> default. In IGNORE NULLS mode FIRST_VALUE calculates first not null value in
> the partiton.
> [Ignore nulls behaviour can be
> simulated|http://rwijk.blogspot.ru/2010/06/simulating-laglead-ignore-nulls.html]
> however it makes sense to support it.
> Here's Oracle DB documentation on the subject:
> http://docs.oracle.com/cd/E16655_01/server.121/e17209/functions073.htm
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