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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (PHOENIX-5116) DistinctPrefixFilterIT fails.
Date Thu, 31 Jan 2019 05:50:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-5116?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16756898#comment-16756898
] 

Lars Hofhansl edited comment on PHOENIX-5116 at 1/31/19 5:49 AM:
-----------------------------------------------------------------

Instead of the table, I had to check the plan whether it has salted key-ranges, and in that
case remove those from consideration in choosing a plan. I think it's fine to leak a bit of
internals to the plan chooser due to the nature of heuristic plan selection.

The change as such should be very uncontroversial. I can LocalIndexIT and DistinctPrefixFilterIT,
both pass now.


was (Author: lhofhansl):
Instead of the table, I had to check the plan whether it has salted key-ranges, and in that
case remove those from consideration in choosing a plan.

The change as such should be very uncontroversial. I can LocalIndexIT and DistinctPrefixFilterIT,
both pass now.

> DistinctPrefixFilterIT fails.
> -----------------------------
>
>                 Key: PHOENIX-5116
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-5116
>             Project: Phoenix
>          Issue Type: Task
>            Reporter: Lars Hofhansl
>            Priority: Major
>         Attachments: 5116.txt
>
>
> Caused by this scenario outlined on PHOENIX-5109:
> {quote}
> This just does not end. Now there's a special case for the following:
> *     compound key of VARCHAR
> *     SELECT DISTINCT <prefix of the key>
> *     Salting is enabled
> *     There is a local index on an unrelated column
> Now Phoenix selects a full local index scan, which is heuristically less efficient...
I think.
> The problem is that there are cases where a plan for a salted table nonetheless gets
a key range that is not salted - does not have the salt range in it. That throws the logic
off in this case.
> {quote}



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