(Ozgun from Citus Data) Yup, good point. This example shards the github_events table on user_id and then shows running count(distinct user_id). Since the shard

(Ozgun from Citus Data) Yup, good point. This example shards the github_events table on user_id and then shows running count(distinct user_id). Since the sharding and count(distinct) column is the same, Citus can push down the count(distinct user_id) to each shard and then sum up the results from those shards. In this case, reshuffles don't come into the picture. In this example, HLLs would be most useful if the user then issued count(distinct repo_id) for example. Citus would then ask for HLL sketches from each shard and add them up on the coordinator node.