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ClickHouse Handler

Overview​

Databend is ClickHouse wire protocol-compatible, allow you to connect to Databend server with Clickhouse client, make it easier for users/developers to use Databend.

ClickHouse Protocol(TCP)​

Databend supports ClickHouse client to connect(Default port is 9000), it is same as you connect to a ClickHouse server.

clickhouse-client --host 127.0.0.1 --port 9000

ClickHouse REST API​

tip

Databend ClickHouse HTTP handler is a simplified version of the implementation, it only providers:

  • Heath check
  • Insert with JSONEachRow format

Health Check​

query=SELECT 1
curl '127.0.0.1:8000/clickhouse/?query=select%201'
Response
1

Insert with JSONEachRow(ndjson)​

note

Databend ClickHouse HTTP handler only supports put ndjson(JSONEachRow in ClickHouse) format values.

ndjson is a newline delimited JSON format:

  • Line Separator is '\n'
  • Each Line is a Valid JSON Value

For example, we have a table:

table t1
CREATE TABLE t1(a TINYINT UNSIGNED);

Insert into t1:

insert into t1 format JSONEachRow
echo -e '{"a": 1}\n{"a": 2}' | curl '127.0.0.1:8000/clickhouse/?query=INSERT%20INTO%20t1%20FORMAT%20JSONEachRow' --data-binary @-

Insert with Authentication​

Use HTTP basic authentication:

echo -e '{"a": 1}\n{"a": 2}' | curl 'user:password@127.0.0.1:8000/clickhouse/?query=INSERT%20INTO%20t1%20FORMAT%20JSONEachRow' --data-binary @-

Compression​

Databend ClickHouse HTTP handler supports the following compression methods:

  • BR
  • DEFLATE
  • GZIP