Re: Num Rows computed by EXPLAIN - Hive

[Pengcheng Xiong]

Did u run "analyze table emp compute statistics" before you run the
explain? thanks.

Pengcheng

On Wed, Feb 8, 2017 at 9:29 PM, Vivek Sharma  wrote:

> Hi,
>
>
> I am new to Hive (just few days of learning).
>
>
> I am an Oracle Performance Expert and am comparing the Explain feature of
> Hive with Oracle Explain Plan command. I have an Internal Table with around
> 100 Rows in it. However, the Explain command in Hive computes this as 33,
> which looks to be huge discrepancy and cause a performance issues (for a
> larger table). Wanted to know the internal calculations of Hive to come out
> with the NUM ROWS. The output is pasted below (The table actually has 100
> Rows) :
>
>
> hive (vivek)> explain select country, empno from emp;
> OK
> Explain
> STAGE DEPENDENCIES:
>   Stage-0 is a root stage
>
> STAGE PLANS:
>   Stage: Stage-0
> Fetch Operator
>   limit: -1
>   Processor Tree:
> TableScan
>   alias: emp
>   Statistics: Num rows: 33 Data size: 3501 Basic stats: COMPLETE
> Column stats: NONE
>   Select Operator
> expressions: country (type: string), empno (type: int)
> outputColumnNames: _col0, _col1
> Statistics: Num rows: 33 Data size: 3501 Basic stats: COMPLETE
> Column stats: NONE
> ListSink
>
> Regards
> Vivek
>
>

Num Rows computed by EXPLAIN - Hive

[Vivek Sharma]

Hi,


I am new to Hive (just few days of learning).


I am an Oracle Performance Expert and am comparing the Explain feature of Hive 
with Oracle Explain Plan command. I have an Internal Table with around 100 Rows 
in it. However, the Explain command in Hive computes this as 33, which looks to 
be huge discrepancy and cause a performance issues (for a larger table). Wanted 
to know the internal calculations of Hive to come out with the NUM ROWS. The 
output is pasted below (The table actually has 100 Rows) :


hive (vivek)> explain select country, empno from emp;
OK
Explain
STAGE DEPENDENCIES:
  Stage-0 is a root stage

STAGE PLANS:
  Stage: Stage-0
Fetch Operator
  limit: -1
  Processor Tree:
TableScan
  alias: emp
  Statistics: Num rows: 33 Data size: 3501 Basic stats: COMPLETE Column 
stats: NONE
  Select Operator
expressions: country (type: string), empno (type: int)
outputColumnNames: _col0, _col1
Statistics: Num rows: 33 Data size: 3501 Basic stats: COMPLETE 
Column stats: NONE
ListSink

Regards
Vivek

Re: Request for write access to the Hive wiki

[Lefty Leverenz]

You've got it.  Welcome to the Hive wiki team, Nanda!

-- Lefty


On Wed, Feb 8, 2017 at 8:31 PM, Nandakumar Vadivelu <
nvadiv...@hortonworks.com> wrote:

> Hi All,
>
>
>
> As part of HIVE-15792 ,
> Hive wiki has to be updated. Requesting write access to update the wiki.
>
>
>
> Confluence username: nandakumar131
>
>
>
>
>
> Thanks,
>
> Nanda
>
>
>

Request for write access to the Hive wiki

[Nandakumar Vadivelu]

Hi All,

As part of HIVE-15792, Hive 
wiki has to be updated. Requesting write access to update the wiki.

Confluence username: nandakumar131


Thanks,
Nanda

FINAL REMINDER: CFP for ApacheCon closes February 11th

[Rich Bowen]

Dear Apache Enthusiast,

This is your FINAL reminder that the Call for Papers (CFP) for ApacheCon
Miami is closing this weekend - February 11th. This is your final
opportunity to submit a talk for consideration at this event.

This year, we are running several mini conferences in conjunction with
the main event, so if you're submitting for one of those events, please
pay attention to the instructions below.

Apache: Big Data
* Event information:
http://events.linuxfoundation.org/events/apache-big-data-north-america
* CFP:
http://events.linuxfoundation.org/events/apache-big-data-north-america/program/cfp

Apache: IoT (Internet of Things)
* Event Information: http://us.apacheiot.org/
* CFP -
http://events.linuxfoundation.org/events/apachecon-north-america/program/cfp
(Indicate 'IoT' in the Target Audience field)

CloudStack Collaboration Conference
* Event information: http://us.cloudstackcollab.org/
* CFP -
http://events.linuxfoundation.org/events/apachecon-north-america/program/cfp
(Indicate 'CloudStack' in the Target Audience field)

FlexJS Summit
* Event information - http://us.apacheflexjs.org/
* CFP -
http://events.linuxfoundation.org/events/apachecon-north-america/program/cfp
(Indicate 'Flex' in the Target Audience field)

TomcatCon
* Event information - https://tomcat.apache.org/conference.html
* CFP -
http://events.linuxfoundation.org/events/apachecon-north-america/program/cfp
(Indicate 'Tomcat' in the Target Audience field)

All other topics and projects
* Event information -
http://events.linuxfoundation.org/events/apachecon-north-america/program/about
* CFP -
http://events.linuxfoundation.org/events/apachecon-north-america/program/cfp

Admission to any of these events also grants you access to all of the
others.

Thanks, and we look forward to seeing you in Miami!

-- 
Rich Bowen
VP Conferences, Apache Software Foundation
rbo...@apache.org
Twitter: @apachecon



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