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https://issues.apache.org/jira/browse/ASTERIXDB-1500?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yingyi Bu reassigned ASTERIXDB-1500:
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Assignee: Dmitry Lychagin (was: Yingyi Bu)
> Inject filters to eliminate null/missing join keys for equality joins
> ---------------------------------------------------------------------
>
> Key: ASTERIXDB-1500
> URL: https://issues.apache.org/jira/browse/ASTERIXDB-1500
> Project: Apache AsterixDB
> Issue Type: Improvement
> Components: COMP - Compiler
> Reporter: Yingyi Bu
> Assignee: Dmitry Lychagin
> Labels: soon
>
> For the following query, there could be many tweets that has the field
> in_reply_to_status_id being null/missing. Therefore, that would skewness of
> for the hash join. Since this is an inner join and missing/null join keys
> anyway could not produce qualified join results, the optimizer should inject
> null/missing filters before the join.
> {noformat}
> FROM Tweets t2 JOIN Tweets t1 ON t2.in_reply_to_status_id = t1.id
> WHERE not(`is-unknown`(t2.in_reply_to_status_id))
> GROUP BY t1.id AS id, t1.user.name AS name, t1.text AS text
> SELECT id, name, text, COUNT(t2) AS num_retweets
> ORDER BY num_retweets DESC
> LIMIT 5;
> {noformat}
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