ClickHouse | ClickHouse® is a free analytics DBMS for big data | Database library

I'm playing with Kafka engine on ClickHouse cluster. At the moment ClickHouse 22.1 cluster and Kafka are run in Docker. Here are configurations: https://github.com/apanasevich/clickhouse-etl-cluster

Here are DDL for Kafka integration:

I've a python script that outputs the input:

I want to use Clickhouse as an OLAP and PostgreSQL as an OLTP database.

The problem is that queries to Clickhouse run slower than on Postgres. The query is as below:

I have a table like:

create table test (id String, timestamp DateTime, somestring String) ENGINE = MergeTree ORDER BY (id, timestamp)

i inserted 100 records then inserted another 100 records and i run select query select * from test clickhouse returning with 2 parts their lengths are 100 and they are ordered in themselves. Then i run the query optimize table test and it started to return with 1 part and its length is 200 and ordered. So should i run optimize query after all insert and does it increase select query performance like select count(*) from test where id = 'foo' ?

I'm setting up clickhouse-backup utility locally. I go through the installation steps and now I'm stuck on the step with changing settings for '.config.yml' file.

I ran sudo ./clickhouse-backup create from the folder where I decompressed the utility and could found created backup in /var/lib/clickhouse/backup

When I execute:

In clickhouse, how can I separate number by comma?

I'm running ClickHouse Docker image on MacBook M1 and getting the following error.

I have a table with products names in PostgreSql database. Total rows is ~30M. And I have history of prices in ClickHouse. I want to join names to prices. DDL to create dictionary:

From the documentation, you have to put a NOT NULL modifier in the column definition to mark it as such, just like for other SQL databases.

Consider this table: