Dandandan commented on issue #18411: URL: https://github.com/apache/datafusion/issues/18411#issuecomment-3707073395
Looking at the the query and profiling, I think there is a nice optimization we can do for optimizing `AVG` that we don't yet do. Quite a bit of time is spent in the (sum/avg/count) accumulators: <img width="1570" height="144" alt="Image" src="https://github.com/user-attachments/assets/3d6ffdd5-0414-4355-8397-f527226c3b5d"; /> ``` select l_returnflag, l_linestatus, sum(l_quantity) as sum_qty, sum(l_extendedprice) as sum_base_price, sum(l_extendedprice * (1 - l_discount)) as sum_disc_price, sum(l_extendedprice * (1 - l_discount) * (1 + l_tax)) as sum_charge, avg(l_quantity) as avg_qty, avg(l_extendedprice) as avg_price, avg(l_discount) as avg_disc, count(*) as count_order from lineitem where l_shipdate <= date '1998-09-02' group by l_returnflag, l_linestatus order by l_returnflag, l_linestatus; ``` Zooming in on the avg: ``` avg(l_quantity) as avg_qty, avg(l_extendedprice) as avg_price, avg(l_discount) as avg_disc, count(*) as count_order ``` Those accumulators will all (redundantly) compute the count. We should be able to rewrite it to use a shared count (and thus faster accumulators): ``` sum(l_quantity) / count_order, sum(l_extendedprice) / count_order, sum(l_discount) as avg_disc, count_order ``` -- 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]
