Materialized views in ClickHouse: The data transformation Swiss Army knife

propeldata.com

17 pointsacossta2 comments

Basically like a persistent view of data which gets modified when the original table changes? Glad to see more data science friendly features being added. Been watching Clickhouse for a while now and I am very impressed.

Correct. Under the hood, they work as insert triggers that automatically update the target whenever the source table changes.

But it's more than that. One neat thing is that it can handle incremental aggregations, such as AVG, SUM, and Percentiles, which would not be doable just with insert triggers. ClickHouse can do this because it stores the intermediate state of the aggregations in special Aggregate Function data types.

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