Clickhouse Cheatsheet

Clickhouse is a OLAP database that stores data in column for fast analytics. There are many advantages to this database as they are using zookeeper management for the cluster. This is very similar in design as the Apache Cassandra.

Delete in Clickhouse

When you delete record in clickhouse, it is not instantaneous and it also does not have explicit commit function. Therefore, the deletes are at leisure of zookeeper and clickhouse.

If you are doing delete and doing pipeline right after, you need to put a sleep to ensure that delete is completed before doing any operation on the table. The records deleted are still visible until it is committed by the system.