When you send an insert statement (that should contain many rows - see section above) to a table in ClickHouse Cloud, and that table is not using a partitioning key then all row data from that insert is written into a new part on storage:
However, when you send an insert statement to a table in ClickHouse Cloud, and that table has a partitioning key, then ClickHouse:
- checks the partitioning key values of the rows contained in the insert
- creates one new part on storage per distinct partitioning key value
- places the rows in the corresponding parts by partitioning key value
Therefore, to minimize the number of write requests to the ClickHouse Cloud object storage, use a low cardinality partitioning key or avoid using any partitioning key for your table.