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From "Pritesh Maker (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DRILL-5774) Excessive memory allocation
Date Fri, 23 Feb 2018 06:07:00 GMT

     [ https://issues.apache.org/jira/browse/DRILL-5774?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Pritesh Maker updated DRILL-5774:
---------------------------------
    Fix Version/s:     (was: 1.13.0)
                   1.14.0

> Excessive memory allocation
> ---------------------------
>
>                 Key: DRILL-5774
>                 URL: https://issues.apache.org/jira/browse/DRILL-5774
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Execution - Relational Operators
>    Affects Versions: 1.11.0
>            Reporter: Robert Hou
>            Assignee: Paul Rogers
>            Priority: Major
>             Fix For: 1.14.0
>
>
> This query exhibits excessive memory allocation:
> {noformat}
> ALTER SESSION SET `exec.sort.disable_managed` = false;
> alter session set `planner.width.max_per_node` = 1;
> alter session set `planner.disable_exchanges` = true;
> alter session set `planner.width.max_per_query` = 1;
> select count(*) from (select * from (select id, flatten(str_list) str from dfs.`/drill/testdata/resource-manager/flatten-large-small.json`)
d order by d.str) d1 where d1.id=0;
> {noformat}
> This query does a flatten on a large table.  The result is 160M records.  Half the records
have a one-byte string, and half have a 253-byte string.  And then there are 40K records with
223 byte strings.
> {noformat}
> select length(str), count(*) from (select id, flatten(str_list) str from dfs.`/drill/testdata/resource-manager/flatten-large-small.json`)
group by length(str);
> +---------+-----------+
> | EXPR$0  |  EXPR$1   |
> +---------+-----------+
> | 223     | 40000     |
> | 1       | 80042001  |
> | 253     | 80000000  |
> {noformat}
> From the drillbit.log:
> {noformat}
> 2017-09-02 11:43:44,598 [26550427-6adf-a52e-2ea8-dc52d8d8433f:frag:0:0] DEBUG o.a.d.e.p.i.x.m.ExternalSortBatch
- Actual batch schema & sizes {
>   str(type: REQUIRED VARCHAR, count: 4096, std size: 54, actual size: 134, data size:
548360)
>   id(type: OPTIONAL BIGINT, count: 4096, std size: 8, actual size: 9, data size: 36864)
>   Records: 4096, Total size: 1073819648, Data size: 585224, Gross row width: 262163,
Net row width: 143, Density: 1}
> {noformat}
> The data size is 585K, but the batch size is 1 GB.  The density is 1%.



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