kpeng1 opened a new issue #11758:
URL: https://github.com/apache/druid/issues/11758


   Please provide a detailed title (e.g. "Broker crashes when using TopN query 
with Bound filter" instead of just "Broker crashes").
   
   ### Affected Version
   
   This happens during an upgrade process and we have so far seen this happen 
when upgrading to .21.1 and when downgrade and upgrading to .20.2
   
   ### Description
   
   After we upgraded our cluster from .20.1 to .21.1, we noticed an issue where 
if we were running a query with a limit, that the aggregates values were coming 
back with inconsistent values.  We would run the exact same queries back to 
back and each time they would return with wildly different values (they could 
be differing by factor of 100s).  What we observed:
   
   - If limit was removed from the query (including turning off auto limit) the 
result would be consistent
   - If we have limit in place but the group by is on values that are 
characters/strings the result would be consistent
   - If we have limit in place but the group by is on numeric values, as long 
as if there is an order by statement and in the order by statement we include 
the numeric field that is in the group by the result would be consistent
   - If we do a fresh install in an environment that hasn't had druid installed 
before or has been wiped clean we were not able to reproduce this issue
   - If we have an environment where the is a mismatch of versions in the 
historical nodes we see this issue.  Ex:  We spin up a cluster where one 
historical node is on version .21.1 and one is on .20.2
   - When we were testing upgrading process again, we see this issue on our on 
premises environment, but were not able to reproduce in EC2 environment.
   - We have ensure that on the environments where we are seeing this issue 
that all the services are on version .21.1 using the status endpoint.
   
   Before filing this ticket, I asked around in the druid forum and I was 
suggested to bring the discussion here.  Here is the druid forum thread: 
https://www.druidforum.org/t/querying-with-a-limit-and-grouping-by-a-numeric-field-returns-inconsistent-results/6680/7
   


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