drill-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-1328) Support table statistics
Date Wed, 18 May 2016 17:36:12 GMT

    [ https://issues.apache.org/jira/browse/DRILL-1328?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15289403#comment-15289403
] 

ASF GitHub Bot commented on DRILL-1328:
---------------------------------------

Github user vkorukanti commented on the pull request:

    https://github.com/apache/drill/pull/425#issuecomment-220101853
  
    Tested with parquet metadata cache. Currently if you do a count(*) on parquet table having
metadata cache, we get that count from cache. For rowcount in planning: if a stats table exists
we get the count from stats table, otherwise we get it from groupscan which in parquet case
gets it from the metadata cache if exists.


> Support table statistics
> ------------------------
>
>                 Key: DRILL-1328
>                 URL: https://issues.apache.org/jira/browse/DRILL-1328
>             Project: Apache Drill
>          Issue Type: Improvement
>            Reporter: Cliff Buchanan
>             Fix For: Future
>
>         Attachments: 0001-PRE-Set-value-count-in-splitAndTransfer.patch
>
>
> This consists of several subtasks
> * implement operators to generate statistics
> * add "analyze table" support to parser/planner
> * create a metadata provider to allow statistics to be used by optiq in planning optimization
> * implement statistics functions
> Right now, the bulk of this functionality is implemented, but it hasn't been rigorously
tested and needs to have some definite answers for some of the parts "around the edges" (how
analyze table figures out where the table statistics are located, how a table "append" should
work in a read only file system)
> Also, here are a few known caveats:
> * table statistics are collected by creating a sql query based on the string path of
the table. This should probably be done with a Table reference.
> * Case sensitivity for column statistics is probably iffy
> * Math for combining two column NDVs into a joint NDV should be checked.
> * Schema changes aren't really being considered yet.
> * adding getDrillTable is probably unnecessary; it might be better to do getTable().unwrap(DrillTable.class)



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

Mime
View raw message