Apache Druid

option a: use a approximation query if possible
option b: set a value to
```druid.query.groupBy.maxMergingDictionarySize=100000000
        druid.query.groupBy.maxOnDiskStorage=2147483648```
on historicals, brokers, and MM

eg: instead of count (distinct column)
use APPROX_COUNT_DISTINCT_DS_THETA(column)

but if you are using array_agg  or distinct array_agg maybe you should remodel your data, if the number of distinct is high you gonna need more memory

Hello Santos!! 
I did the same as you suggested.. but still I'm not getting the result.. instead I'm getting 504 error

504 is a timeout, this query might just be taking a really long time

i would first consider rethinking your approach as Renato has mentioned — maybe there is a more effective way to do the thing you are trying to do?

or if you want to hit it with the brute force hammer, if the result set is large or if the query processing is intense, you can raise various timeouts as described on <https://support.imply.io/hc/en-us/articles/360034310953-Tuning-Druid-for-Large-Result-Sets>. you would not hit these unless your query is taking ~minutes