[jira] [Assigned] (IMPALA-5004) Switch to sorting node for large TopN queries

["Lars Volker (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-5004?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Lars Volker reassigned IMPALA-5004:
-----------------------------------

    Assignee: Sahil Takiar

> Switch to sorting node for large TopN queries
> ---------------------------------------------
>
>                 Key: IMPALA-5004
>                 URL: https://issues.apache.org/jira/browse/IMPALA-5004
>             Project: IMPALA
>          Issue Type: Improvement
>          Components: Frontend
>    Affects Versions: Impala 2.9.0
>            Reporter: Lars Volker
>            Assignee: Sahil Takiar
>            Priority: Major
>
> As explained by [~tarmstrong] in IMPALA-4995:
> bq. We should also consider switching to the sort operator for large limits. This allows it to spill. The memory requirements for TopN also are problematic for large limits, since it would allocate large vectors that are untracked and also require a large amount of contiguous memory.
> There's already logic to select TopN vs. Sort: [planner/SingleNodePlanner.java#L289|https://github.com/apache/incubator-impala/blob/master/fe/src/main/java/org/apache/impala/planner/SingleNodePlanner.java#L289]



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