drill-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jacques Nadeau (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DRILL-2192) DrillScanRel should differentiate skip-all & scan-all & scan-some semantics while creating a GroupScan [umbrella]
Date Tue, 05 May 2015 13:38:23 GMT

     [ https://issues.apache.org/jira/browse/DRILL-2192?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jacques Nadeau updated DRILL-2192:
----------------------------------
    Fix Version/s:     (was: 1.0.0)
                   1.2.0

> DrillScanRel should differentiate skip-all & scan-all & scan-some semantics while
creating a GroupScan [umbrella]
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: DRILL-2192
>                 URL: https://issues.apache.org/jira/browse/DRILL-2192
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Query Planning & Optimization
>            Reporter: Hanifi Gunes
>            Assignee: Steven Phillips
>             Fix For: 1.2.0
>
>
> DrillScanRel passes a list of columns to be read into GroupScan. Currently the logic
here is to scan all of the columns even if planner asks to skip them all. Skipping all of
the columns is particularly beneficial for the case of count(star) that is translated to count(constant)
where we just need row count but not the actual data.
> The idea is to distinguish three separate states depending on the output coming from
planner as follows:
> | list of columns from planner | scan semantics |
> | null | scan-all |
> | empty list of columns | skip-all |
> | non-empty list of columns w/o star | scan-some |
> | list of columns with star | scan-all |
> As part this umbrella, we should make readers understand skip-all semantics.



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

Mime
View raw message