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https://issues.apache.org/jira/browse/HIVE-24262?focusedWorklogId=511166&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-511166
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ASF GitHub Bot logged work on HIVE-24262:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 13/Nov/20 01:42
Start Date: 13/Nov/20 01:42
Worklog Time Spent: 10m
Work Description: mustafaiman closed pull request #1627:
URL: https://github.com/apache/hive/pull/1627
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Issue Time Tracking
-------------------
Worklog Id: (was: 511166)
Remaining Estimate: 0h
Time Spent: 10m
> Optimise NullScanTaskDispatcher for cloud storage
> -------------------------------------------------
>
> Key: HIVE-24262
> URL: https://issues.apache.org/jira/browse/HIVE-24262
> Project: Hive
> Issue Type: Improvement
> Reporter: Rajesh Balamohan
> Assignee: Mustafa İman
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> {noformat}
> select count(DISTINCT ss_sold_date_sk) from store_sales;
> ----------------------------------------------------------------------------------------------
> VERTICES MODE STATUS TOTAL COMPLETED RUNNING PENDING
> FAILED KILLED
> ----------------------------------------------------------------------------------------------
> Map 1 .......... container SUCCEEDED 1 1 0 0
> 0 0
> Reducer 2 ...... container SUCCEEDED 1 1 0 0
> 0 0
> ----------------------------------------------------------------------------------------------
> VERTICES: 02/02 [==========================>>] 100% ELAPSED TIME: 5.55 s
> ----------------------------------------------------------------------------------------------
> INFO : Status: DAG finished successfully in 5.44 seconds
> INFO :
> INFO : Query Execution Summary
> INFO :
> ----------------------------------------------------------------------------------------------
> INFO : OPERATION DURATION
> INFO :
> ----------------------------------------------------------------------------------------------
> INFO : Compile Query 102.02s
> INFO : Prepare Plan 0.51s
> INFO : Get Query Coordinator (AM) 0.01s
> INFO : Submit Plan 0.33s
> INFO : Start DAG 0.56s
> INFO : Run DAG 5.44s
> INFO :
> ----------------------------------------------------------------------------------------------
> {noformat}
> Reason for "102 seconds" compilation time is that, it ends up doing
> "isEmptyPath" check for every partition path and takes lot of time in
> compilation phase.
> If the parent directory of all paths belong to the same path, we could just
> do a recursive listing just once (instead of listing each directory one at a
> time sequentially) in cloud storage systems.
> https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/NullScanTaskDispatcher.java#L158
> https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/NullScanTaskDispatcher.java#L121
> https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/NullScanTaskDispatcher.java#L101
> With a temp hacky fix, it comes down to 2 seconds from 100+ seconds.
> {noformat}
> INFO : Dag name: select count(DISTINCT ss_sold_...store_sales (Stage-1)
> INFO : Status: Running (Executing on YARN cluster with App id
> application_1602500203747_0003)
> ----------------------------------------------------------------------------------------------
> VERTICES MODE STATUS TOTAL COMPLETED RUNNING PENDING
> FAILED KILLED
> ----------------------------------------------------------------------------------------------
> Map 1 .......... container SUCCEEDED 1 1 0 0
> 0 0
> Reducer 2 ...... container SUCCEEDED 1 1 0 0
> 0 0
> ----------------------------------------------------------------------------------------------
> VERTICES: 02/02 [==========================>>] 100% ELAPSED TIME: 1.23 s
> ----------------------------------------------------------------------------------------------
> INFO : Status: DAG finished successfully in 1.20 seconds
> INFO :
> INFO : Query Execution Summary
> INFO :
> ----------------------------------------------------------------------------------------------
> INFO : OPERATION DURATION
> INFO :
> ----------------------------------------------------------------------------------------------
> INFO : Compile Query 0.85s
> INFO : Prepare Plan 0.17s
> INFO : Get Query Coordinator (AM) 0.00s
> INFO : Submit Plan 0.03s
> INFO : Start DAG 0.03s
> INFO : Run DAG 1.20s
> INFO :
> ----------------------------------------------------------------------------------------------
> {noformat}
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