aggregation_* session settings

These settings are available in system.settings and are autogenerated from source.

aggregation_in_order_max_block_bytes

Maximal size of block in bytes accumulated during aggregation in order of primary key. Lower block size allows to parallelize more final merge stage of aggregation.

aggregation_memory_efficient_merge_threads

Number of threads to use for merge intermediate aggregation results in memory efficient mode. When bigger, then more memory is consumed. 0 means - same as ‘max_threads’.