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Subject [GitHub] [drill] amansinha100 commented on a change in pull request #1728: DRILL-7089: Implement caching for TableMetadataProvider at query level and adapt statistics to use Drill metastore API
Date Sun, 07 Apr 2019 19:06:16 GMT
amansinha100 commented on a change in pull request #1728: DRILL-7089: Implement caching for
TableMetadataProvider at query level and adapt statistics to use Drill metastore API
URL: https://github.com/apache/drill/pull/1728#discussion_r272846760
 
 

 ##########
 File path: exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/DrillTable.java
 ##########
 @@ -49,9 +50,7 @@
   private final String userName;
   private GroupScan scan;
   private SessionOptionManager options;
-  // Stores the statistics(rowcount, NDV etc.) associated with the table
-  private DrillStatsTable statsTable;
-  private TupleMetadata schema;
+  private MetadataProviderManager metadataProviderManager;
 
 Review comment:
   The fact that the DrillTable has a reference to the `MetadataProviderManager` rather than
the `MetadataProvider` itself is significant..I suppose you are following a particular Design
Pattern .. probably the Facade Pattern [1] ?  The MetadataProvider also follows the Builder
pattern, so there's 2 levels of indirection:  Manager --> Provider --> Builder.   My
initial thought was that 'do we need both or could a Provider be able to create instances
for multiple tables, so a Provider --> Builder be sufficient ?  Your approach is that there's
a  1-to-many relationship between Manager-->Provider and a 1-to-1 relationship between
a Provider and its associated DrillTable.  Is that correct ?   
   
   [1] https://en.wikipedia.org/wiki/Facade_pattern

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