pvary commented on pull request #3328:
URL: https://github.com/apache/iceberg/pull/3328#issuecomment-949532847


   Sorry for the many short comments (not too much time today), but let me 
summarise:
   - We should double check everything which I am stating here for Hive 
2.3.8/9, and 3.1.2 - We were working on Hive 4.0.0 when considered stats.
   - We found that the estimation causes issues for tables with plenty of 
files. If we turn off `hive.stats.estimate` then we do not end up listing the 
directories recursively, so that could fix the planning performance issue
   - We found that if the `hive.stats.autogather` is true, then the statistics 
are collected, but there was problem with the `rowDataSize`. We fixed this in 
HIVE-24928 using the Iceberg table statistics where we propagate the Iceberg 
statistics to use as Hive statistics.
   - For automatic Column statistics we need: HIVE-25276
   - We still has to consider other engines writing these tables, and we have 
to invalidate column statistics, if other engine is update the table. For this 
we created this change: HIVE-25286
   
   I hope this finally helps 😄 


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