kfaraz commented on PR #19685:
URL: https://github.com/apache/druid/pull/19685#issuecomment-4980740267

   > I saw some improvements if I reduce the limit of number of intervals from 
10000 to 100 which I feel would also improve this query in general and hit the 
indexes since the number of rows scans would reduce with a data source filters.
   This is all on mysql 8.0 though.
   
   Yeah, please hold off on reducing the limit, as it will drastically reduce 
the efficiency of the kill duty.
   
   I have been running the queries on MySQL 8 (with GROUP BY columns reversed 
and changing limits) on a druid_segments table with more than 15M unused 
segments for a single datasource and the results for that datasource have been 
consistently the same irrespective of the query (i.e. the GROUP BY order and 
the limit does not really affect the query perf).
   I got the same results as you with the EXPLAIN query, but the actual SELECT 
query took the same time.
   
   > the number of rows scans would reduce with a data source filters
   
   Yes, but changing the limit will not affect this.


-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: [email protected]

For queries about this service, please contact Infrastructure at:
[email protected]


---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]

Reply via email to