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Ethan Wang commented on CALCITE-1588: ------------------------------------- regarding syntax {code}COUNT(DISTINCT customerId) APPROXIMATE (WITHIN 10 PERCENT)){code} Seems to me Druid implemented the approx distinct count using HyperLogLog. In HyperLogLog, I don't think it's common for user to specify the accuracy, since the accuracy is implied in the algorithm and only related to a constant. So the goal is always "as most accurate as possible". Is that true in Druid? [~gian] > Add SQL syntax to allow approximate LIMIT and distinct-COUNT > ------------------------------------------------------------ > > Key: CALCITE-1588 > URL: https://issues.apache.org/jira/browse/CALCITE-1588 > Project: Calcite > Issue Type: Bug > Reporter: Julian Hyde > Assignee: Julian Hyde > > Add SQL syntax to allow approximate LIMIT and distinct-COUNT. These will set > the properties specified in CALCITE-1587. By default the properties are > false, so the query will return exact results. > Exact syntax is to be decided. It could be at the top of the query (therefore > affecting every LIMIT or aggregate in the query) or it could be more > localized (e.g. {{COUNT(DISTINCT customerId) APPROXIMATE (WITHIN 10 > PERCENT)}}). -- This message was sent by Atlassian JIRA (v6.4.14#64029)