asolimando commented on code in PR #3137:
URL: https://github.com/apache/hive/pull/3137#discussion_r1045927909


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ql/src/test/results/clientpositive/beeline/colstats_all_nulls.q.out:
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@@ -73,6 +74,7 @@ max_col_len
 num_trues      
 num_falses     
 bit_vector     HL
+histogram      

Review Comment:
   We have two config knobs for enabling histogram/KLL, one is 
`hive.stats.kll.enable` (for turning it on/off during statistics computation), 
the other is `metastore.stats.fetch.kll` (which turns on/off the retrieval from 
the metastore).
   
   If we were to implement this, would you show/hide the **histogram** line for 
the `DESCRIBE FORMATTED` command based on the value of 
`metastore.stats.fetch.kll` alone?
   
   I thought of this at some point, but the fact that it hasn't been done for 
HLL even in the first PR refrained me from implementing it.
   
   The reason is that we would end up having an inconsistent behaviour w.r.t. 
HLL which is always displayed, no matter what the configuration is for the 
corresponding `metastore.stats.fetch.bitvector` parameter.
   
   This said, I don't have strong feelings either way and I am fine 
implementing the hiding mechanism and it wouldn't take much, I just wanted to 
expose my reasoning so far to have all the pros/cons on the table.



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