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Subject [GitHub] [drill] paul-rogers commented on a change in pull request #2026: DRILL-7330: Implement metadata usage for all format plugins
Date Sun, 15 Mar 2020 05:10:48 GMT
paul-rogers commented on a change in pull request #2026: DRILL-7330: Implement metadata usage
for all format plugins
URL: https://github.com/apache/drill/pull/2026#discussion_r392631705
 
 

 ##########
 File path: exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/scan/file/ImplicitColumnManager.java
 ##########
 @@ -199,6 +192,21 @@ public ImplicitColumnManager(OptionSet optionManager,
     }
   }
 
+  /**
+   * Specifies whether to plan based on the legacy meaning of "*". See
+   * <a href="https://issues.apache.org/jira/browse/DRILL-5542">DRILL-5542</a>.
+   * If true, then the star column <i>includes</i> implicit and partition
+   * columns. If false, then star matches <i>only</i> table columns.
+   *
+   * @param optionManager access to the options for this query; used
+   *                      too look up custom names for the metadata columns
+   * @param config        implicit column options
+   */
+  public ImplicitColumnManager(OptionSet optionManager,
 
 Review comment:
   Help me understand your intent. Older Drill versions always expanded implicit columns in
wildcard queries. Then the project threw away those columns. We changed this so that the user
asks for the columns they want. We could do this because Calcite changed (as I understand
it) so that it will allow a projection list of the form `SELECT *, filename`.
   
   Does metadata need the implicit columns expanded for a wildcard query? Is this the behavior
for the other, non-EVF readers?
   
   If so, we'll need a way to identify a metadata query (which needs those columns) vs. other
queries (do not need them and don't want to pay the cost.)

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