Clickhouse allows high performance writes but only if they are done in bulk and with intervals (recommended is at least 1 second interval between inserts). In the documentation to JDBC connector for Clickhouse batchSize option exists but there is nothing about intervals between inserts and I didn't manage to find insertion logic in the code (I am not a Java guy though).
Does it mean there are no intervals and Pulsar simply does inserts as frequently as it can?
I know nothing about Pulsar.
recommended is at least 1 second interval between inserts
That recommendation is "one insert per second". Nothing about 1 second to sleep.
This recommendation is too basic and very vague.
Every project is unique, has own environment and requirements.
In one project I insert 10mil. very wide rows per minute with RAID 10 with HDD disks.
In another project I do 1000 inserts with ~100 narrow rows each per second using In-memory parts with single NVME disk.