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https://issues.apache.org/jira/browse/DRILL-5885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16208623#comment-16208623
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Paul Rogers commented on DRILL-5885:
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Note that this ticket describes the underlying behavior in Drill that triggered
DRILL-5670. That is, why does Drill need to allocate a buffer 2x the data size
in order to deserialize from disk? This is wasteful and inefficient. This
ticket asks to find a way to allocate data no more inefficiently than the
original vectors. Since Drill uses power-of-two rounding for allocations, the
average internal fragmentation should be 25%, meaning that we generally need 1
1/3 more memory than data size, on average. We don't want to use 2x when
reading from spill files.
> Drill consumes 2x memory when sorting and reading a spilled batch from disk.
> ----------------------------------------------------------------------------
>
> Key: DRILL-5885
> URL: https://issues.apache.org/jira/browse/DRILL-5885
> Project: Apache Drill
> Issue Type: Bug
> Components: Execution - Relational Operators
> Affects Versions: 1.11.0
> Reporter: Robert Hou
>
> The query is:
> {noformat}
> select count(*) from (select * from
> dfs.`/drill/testdata/resource-manager/3500cols.tbl` order by
> columns[450],columns[330],columns[230],columns[220],columns[110],columns[90],columns[80],columns[70],columns[40],columns[10],columns[20],columns[30],columns[40],columns[50],
>
> columns[454],columns[413],columns[940],columns[834],columns[73],columns[140],columns[104],columns[2222],columns[30],columns[2420],columns[1520],
> columns[1410],
> columns[1110],columns[1290],columns[2380],columns[705],columns[45],columns[1054],columns[2430],columns[420],columns[404],columns[3350],
>
> columns[3333],columns[153],columns[356],columns[84],columns[745],columns[1450],columns[103],columns[2065],columns[343],columns[3420],columns[530],
> columns[3210] ) d where d.col433 = 'sjka skjf';
> {noformat}
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