[jira] [Closed] (DRILL-5267) Managed external sort spills too often with Parquet data

["Dechang Gu (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DRILL-5267?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dechang Gu closed DRILL-5267.
-----------------------------

Verified and added test case to perf framework. Here are the numbers:

Drill version (gitid)	Query tm (ms)	Max Batches	note
41ffed5	44596	159	1.11.0 current master
8cded5a	37869	159	commit with the fix
33fc25c	77857	1271	commit prior the fix
33fc25c	1277695	1271	without setting "sort.external.disable_managed:false" in drill-override.conf

> Managed external sort spills too often with Parquet data
> --------------------------------------------------------
>
>                 Key: DRILL-5267
>                 URL: https://issues.apache.org/jira/browse/DRILL-5267
>             Project: Apache Drill
>          Issue Type: Sub-task
>    Affects Versions: 1.10.0
>            Reporter: Paul Rogers
>            Assignee: Paul Rogers
>             Fix For: 1.10.0
>
>
> DRILL-5266 describes how Parquet produces low-density record batches. The result of these batches is that the external sort spills more frequently than it should because it sizes spill files based on batch size, not data content of the batch. Since Parquet batches are 95% empty space, the spill files end up far too small.
> Adjust the spill calculations based on actual data content, not the size of the overall record batch.



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