Materialized Views and Projections Under the Hood

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This video looks under the hood of Materialized Views and Projections in ClickHouse and explains how automatic incremental data transformation works in ClickHouse. For more like this, go take our free training in ClickHouse Academy: learn.clickhou....

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2 окт 2024

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Комментарии : 12

@zingsting9595 10 месяцев назад

This should be one of the first videos to be presented to clickhouse noobs as it contains the very basic concept of parts and merges that are not very well introduced in the written documentation. Either update the docs or change the title of the video to intro to clickhouse.

@joesligo1516 Год назад

Extremely helpful video, particularly explaining the concepts on agg mergetrees in theory never merging to a single file. It was very counterintuitive for me at first.

@mayankpant5376 Год назад

Projection is great. if you have very defined use-case, it abstracts away all the complexity of materialized view. Will we be able to create separate indexes on projection queries too?

@belferman Год назад

Fantastic explanation, made it very simple. Thanks!

@karthikv2k Год назад

If i create a projection on a table that has data, will the project process both existing and new data to that table or just only new inserts?

@ClickHouseDB Год назад

Sorry for delay. I will ask and let you know. You can also, always, join our Slack to chat in realtime.

@ClickHouseDB Год назад

If you just create the projection (ALTER TABLE ... ADD PROJECTION ...) then only new inserts are processed also by the projection. But if you create + materialize (ALTER TABLE ... ADD PROJECTION ... + ALTER TABLE ... MATERIALIZE PROJECTION ...), then also all existing data is transformed. You can see an example in this tutorial: clickhouse.com/docs/en/getting-started/example-datasets/uk-price-paid#speedup-with-projections