[
https://issues.apache.org/jira/browse/KUDU-2380?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16415861#comment-16415861
]
Todd Lipcon commented on KUDU-2380:
-----------------------------------
Attached pprof file from this server (viewable using the tool from 'go get
github.com/google/pprof')
> Selective predicates when selecting high number of columns burns CPU in
> SerializeRowBlock
> -----------------------------------------------------------------------------------------
>
> Key: KUDU-2380
> URL: https://issues.apache.org/jira/browse/KUDU-2380
> Project: Kudu
> Issue Type: Improvement
> Components: tserver
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Major
> Attachments: pprof.kudu-tserver.samples.cpu.001.pb.gz
>
>
> Testing a table with 280 columns, I found the following performance
> characteristic:
> - scanning all 280 columns with a selective non-key predicate which matches 0
> rows took 8.28s
> - scanning no columns (count query) with the same predicate which matches 0
> rows took 314ms.
> This suggests that we are burning 96% of our CPU doing useless work for this
> query.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
