drill-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Venki Korukanti (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (DRILL-3884) Hive native scan has lower parallelization leading to performance degradation
Date Fri, 02 Oct 2015 20:19:26 GMT

     [ https://issues.apache.org/jira/browse/DRILL-3884?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Venki Korukanti resolved DRILL-3884.
------------------------------------
    Resolution: Fixed

> Hive native scan has lower parallelization leading to performance degradation
> -----------------------------------------------------------------------------
>
>                 Key: DRILL-3884
>                 URL: https://issues.apache.org/jira/browse/DRILL-3884
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization, Storage - Hive
>    Affects Versions: 1.2.0
>            Reporter: Venki Korukanti
>            Assignee: Venki Korukanti
>            Priority: Critical
>             Fix For: 1.2.0
>
>
> Currently {{HiveDrillNativeParquetScan.getScanStats()}} divides the rowCount got from
{{HiveScan}} by a factor and returns that as cost. Problem is all cost calculations and parallelization
depends on the rowCount. Value {{cpuCost}} is not taken into consideration in current cost
calculations in {{ScanPrel}}. In order for the planner to choose {{HiveDrillNativeParquetScan}}
over {{HiveScan}}, rowCount has to be lowered for the former, but this leads to lower parallelization
and performance degradation.
> Temporary fix for Drill 1.2 before DRILL-3856 fully resolves considering CPU cost in
cost model:
> 1. Change ScanPrel to consider the CPU cost in given Stats from GroupScan
> 2. Have higher CPU cost for {{HiveScan}} (SerDe route)
> 3. Lower CPU cost for {{HiveDrillNativeParquetScan}}



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message