ClickHouse provides two types of client APIs over HTTP and TCP protocols respectively.
HTTP is mainly used to support simple lightweight operations and suitable in cross-platform and cross-programming language scenarios. The
clickhouse-server process on the EMR cluster can start the HTTP service at port 8123 to send simple
GET requests in order to check whether the service is normal.
$ curl http://127.0.0.1:8123 Ok.
You can also send requests through
query parameters. For example, the following sample code is to query data in the
account table in
$ wget -q -O- 'http://127.0.0.1:8123/?query=SELECT * from testdb.account' 1 GHua WuHan Hubei 1990 2 SLiu ShenZhen Guangzhou 1991 3 JPong Chengdu Sichuan 1992
For other methods, please see HTTP Interface.
TCP is used mainly on
clickhouse-client. You can enter the
clickhouse-client command in the EMR cluster to get information such as the version information, address of the connected
clickhouse-server, and database used by default. You can run
q to exit.
$ clickhouse-client ClickHouse client version 126.96.36.199. Connecting to localhost:9000 as user default. Connected to ClickHouse server version 19.16.12 revision 54427.
Key parameters used by
For other parameters, please see Command-line Client.