Hi Druid community, it's great to be around. I am learning a lot about Druid lately. I am checking some tuning parameters and I am wondering, is there a direct correlation between these two parameters(recommendation):

druid_processing_numThreads=5
druid_processing_numMergeBuffers=2

i.e - I increased numThreads and worker capacity for example. Should I also increase numMergeBuffers. How is it affected? Any documentation pointers about this? Thanks in advance!

processing.numThreads

controls how many total threads are available for query processing.

numMergeBuffers

is only used when running

groupBy

queries. So, if you have a high percentage of

groupBy

queries, you may want to increase the

numMergeBuffers

Just keep in mind that if you increase the

numMergeBuffers

you may need to increase the

maxDirectMemory

size to accommodate the additional buffers .