Zhangshunyu commented on issue #3701: [WIP]  improve pure partition count star 
performance
URL: https://github.com/apache/carbondata/pull/3701#issuecomment-612715844
 
 
   @ajantha-bhat 
   We find that select count() for some partitons is time costly and worse than 
parquet, as currently the count() with filter whose culumns are all partition 
columns will load all datamaps of these partitions including block info/minmax 
info, but it is no need to load them ,we can just read it from valid index 
files directly using partition prune as the rowCount stored inside index files, 
and we can cache these info. For no-sort partition table, minmax is almost no 
using but cost time.

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