(Marco from Citus Data) Pre-aggregation is less common in data warehouses use-cases than it is in real-time use-cases. Data warehouses are generally used by a

(Marco from Citus Data) Pre-aggregation is less common in data warehouses use-cases than it is in real-time use-cases. Data warehouses are generally used by a small number of users that run ad-hoc reporting queries and can take anywhere from several seconds to a day to complete. With queries changing frequently and high query times being acceptable, pre-aggregation does not provide that much benefit. Citus is meant for applications with a large number of users (e.g. dashboards [1]). Investing in pre-aggregation is often worth doing because it makes for more responsive applications and lower hardware cost. > It's fragile: in this example, it depends on your data coming in exactly-once, in-order. The solution proposed in the blog post does allow out-of-order writes since it only looks at the database clock. Exactly-once delivery depends on a) the database clock not going backwards, b) writes taking less than a minute. However, it is also possible to guarantee exactly-once delivery with a more complex solutions (e.g. create staging table, or use a version number that gets increased atomically through some locks). [1] https://blog.cloudflare.com/scaling-out-postgresql-for-cloudflare-analytics-using-citusdb/ https://blog.cloudflare.com/scaling-out-postgresql-for-cloud...