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https://issues.apache.org/jira/browse/PHOENIX-1560?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14279503#comment-14279503
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Maryann Xue commented on PHOENIX-1560:
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For this case, we can clearly tell that the distinct can be omitted, but it's
just hard for the SubqueryRewriter to know in general. There has to be a way to
let the SubqueryRewriter know. Another way is to post-fix the inner query if we
find out it will be a SKIP-SCAN-JOIN instead of a regular SEMI-JOIN. I'll
quickly check if it's feasible.
> Join between global index and data table if INDEX hint used
> -----------------------------------------------------------
>
> Key: PHOENIX-1560
> URL: https://issues.apache.org/jira/browse/PHOENIX-1560
> Project: Phoenix
> Issue Type: Bug
> Reporter: James Taylor
> Assignee: Maryann Xue
> Attachments: 1560.patch, 1560.v2.patch
>
>
> We already have an INDEX hint, and we already have a mechanism to collect
> referenced columns in the data table that are not in the index table (used
> only for local indexes currently). Instead of not using the global index when
> a referenced data column is not found in the index, we should rewrite the
> query to join back to the data table when the INDEX hint is present. This is
> always possible, as we always have the data PK columns in the index table,
> and our join optimization would kick in as well.
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