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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-1328) Support table statistics
Date Wed, 18 May 2016 23:19:12 GMT

    [ https://issues.apache.org/jira/browse/DRILL-1328?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15290068#comment-15290068
] 

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

Github user sudheeshkatkam commented on a diff in the pull request:

    https://github.com/apache/drill/pull/425#discussion_r63799874
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/store/dfs/FormatPlugin.java
---
    @@ -48,7 +48,7 @@
     
       public FormatMatcher getMatcher();
     
    -  public AbstractWriter getWriter(PhysicalOperator child, String location, List<String>
partitionColumns) throws IOException;
    +  public AbstractWriter getWriter(PhysicalOperator child, String location, boolean append,
List<String> partitionColumns) throws IOException;
    --- End diff --
    
    Could pass a map of options, when "append" is an option?


> 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)



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