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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