[jira] [Commented] (DRILL-7723) Add Excel Metadata as Implicit Fields

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-7723?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17134318#comment-17134318 ] 

ASF GitHub Bot commented on DRILL-7723:
---------------------------------------

cgivre commented on a change in pull request #2069:
URL: https://github.com/apache/drill/pull/2069#discussion_r439499328



##########
File path: contrib/format-excel/src/main/java/org/apache/drill/exec/store/excel/ExcelBatchReader.java
##########
@@ -56,60 +61,70 @@
   private static final Logger logger = org.slf4j.LoggerFactory.getLogger(ExcelBatchReader.class);
 
   private static final String SAFE_WILDCARD = "_$";
-
   private static final String SAFE_SEPARATOR = "_";
-
   private static final String PARSER_WILDCARD = ".*";
-
   private static final String HEADER_NEW_LINE_REPLACEMENT = "__";
-
   private static final String MISSING_FIELD_NAME_HEADER = "field_";
 
-  private static final int ROW_CACHE_SIZE = 100;
+  private enum IMPLICIT_STRING_COLUMNS {
+    _category,

Review comment:
       @vvysotskyi 
   To clarify, the fields here are metadata fields and I wanted to make sure that they do not conflict with fields that might actually be in the users' data.  It is a fairly standard practice to begin metadata fields with an `_`.  I've seen this done in many other platforms.  
   
   In any event, how would you like me to proceed with this?
   




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> Add Excel Metadata as Implicit Fields
> -------------------------------------
>
>                 Key: DRILL-7723
>                 URL: https://issues.apache.org/jira/browse/DRILL-7723
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Metadata, Storage - Text & CSV
>    Affects Versions: 1.17.0
>            Reporter: Charles Givre
>            Assignee: Charles Givre
>            Priority: Major
>             Fix For: 1.18.0
>
>
> Excel files contain a significant number of metadata fields in them. This PR adds the ability to access these fields via implicit columns. The columns are:
> _category
> _content_status
> _content_type;
> _creator
> _description
> _identifier
> _keywords
> _last_modified_by_user
> _revision
> _subject
> _title
> _created
> _last_printed
> _modified
> These fields are not projected in star queries so there is no effect on existing queries.
>  



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