[jira] [Resolved] (PHOENIX-2167) Add new interface in QueryPlan for pushing down a limit value.

["Maryann Xue (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PHOENIX-2167?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Maryann Xue resolved PHOENIX-2167.
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    Resolution: Fixed

> Add new interface in QueryPlan for pushing down a limit value.
> --------------------------------------------------------------
>
>                 Key: PHOENIX-2167
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-2167
>             Project: Phoenix
>          Issue Type: Sub-task
>            Reporter: Maryann Xue
>            Assignee: Maryann Xue
>         Attachments: PHOENIX-2167.patch
>
>   Original Estimate: 48h
>  Remaining Estimate: 48h
>
> Calcite rel trees are compiled bottom-up into Phoenix QueryPlans, the easiest way to implement a Limit RelNode in the tree is to create a ClientScanPlan with the limit value and wrap it around the inner plan. However, oftentimes this may not be efficient.
> For example, select * from T limit 10, the original Phoenix compiler would generate a ScanPlan with limit 10, apply a PageFilter and avoid using sophisticated or expensive ResultIterators.
> So it would make sense to push down the limit to a QueryPlan as low as possible and create a new copy of the plan based on this rule.



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