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https://issues.apache.org/jira/browse/DRILL-4287?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15146849#comment-15146849
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ASF GitHub Bot commented on DRILL-4287:
---------------------------------------

Github user jacques-n commented on a diff in the pull request:

    https://github.com/apache/drill/pull/376#discussion_r52854912
  
    --- Diff: 
exec/java-exec/src/main/java/org/apache/drill/exec/store/dfs/FileSelection.java 
---
    @@ -45,6 +48,10 @@
       public List<String> files;
       public final String selectionRoot;
     
    +  private boolean checkedForDirectories = false; // whether we have 
already checked for directories
    --- End diff --
    
    Can we move from three separate boolean states to one state enumeration?


> Do lazy reading of parquet metadata cache file
> ----------------------------------------------
>
>                 Key: DRILL-4287
>                 URL: https://issues.apache.org/jira/browse/DRILL-4287
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization
>    Affects Versions: 1.4.0
>            Reporter: Aman Sinha
>            Assignee: Jinfeng Ni
>
> Currently, the parquet metadata cache file is read eagerly during creation of 
> the DrillTable (as part of ParquetFormatMatcher.isReadable()).  This is not 
> desirable from performance standpoint since there are scenarios where we want 
> to do some up-front optimizations - e.g. directory-based partition pruning 
> (see DRILL-2517) or potential limit 0 optimization etc. - and in such 
> situations it is better to do lazy reading of the metadata cache file.   
> This is a placeholder to perform such delayed reading since it is needed for 
> the aforementioned optimizations.  



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