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From "Anoop Sam John (JIRA)" <>
Subject [jira] [Commented] (PHOENIX-1278) Performance degradation for salted tables with guideposts
Date Tue, 23 Sep 2014 05:17:33 GMT


Anoop Sam John commented on PHOENIX-1278:

Np Ram.  Pls take it.

> Performance degradation for salted tables with guideposts
> ---------------------------------------------------------
>                 Key: PHOENIX-1278
>                 URL:
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: James Taylor
>            Assignee: Anoop Sam John
> When a table is salted, we're seeing a degradation in performance using our new guidepost-based
parallelization. With salted tables, we do a merge sort with the results from all the parallel
scans. I suspect the cause here is that we're doing a merge sort now between more chunks than
before (since we chunk everything up more now than we used to). We should group the scans
we're doing for the same bucket together and do a concat with those results and then do a
merge sort only with the concatenated batches.
> Pls revert PHOENIX-1279 when we implement this.

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