[GitHub] drill issue #671: DRILL-4347: Propagate distinct row count for joins from lo...

[jinfengni <gi...@git.apache.org>]

Github user jinfengni commented on the issue:

    https://github.com/apache/drill/pull/671
  
    @jacques-n , CachingRelMetadataProvider provides caching capability per meta-method / rel node [1]. Since Drill logical rel (DrillJoinRel) and Drill physical rel (JoinPrel) are different rels, CachingRelMetadataProvider probably would not help avoiding the first meta data call for the physical rel nodes, even the meta data for logical rels are in the cache. 
    
    @julianhyde , I probably once tried to cherry-pick CALCITE-604 to Drill's calcite fork, and I aborted that effort after seeing many merging conflicts (If I remember correctly).  Since there has been ongoing effort to rebase Drill onto latest Calcite,  it might make sense to see if the rebase work could be done shortly. At that time, Drill will benefit from CALCITE-604.
    
     
    1. https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rel/metadata/CachingRelMetadataProvider.java#L113-L120



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