/clickhouse-go

Golang driver for ClickHouse

Primary LanguageGoApache License 2.0Apache-2.0

ClickHouse run-tests Go Reference

Golang SQL database driver for ClickHouse.

Versions

There are two version of this driver, v1 and v2, available as separate branches.

v1 is now in a state of a maintenance - we will only accept PRs for bug and security fixes.

Users should use v2 which is production ready and significantly faster than v1.

Supported ClickHouse Versions

The driver is tested against the currently supported versions of ClickHouse

Key features

Support for the ClickHouse protocol advanced features using Context:

  • Query ID
  • Quota Key
  • Settings
  • OpenTelemetry
  • Execution events:
    • Logs
    • Progress
    • Profile info
    • Profile events

database/sql interface

OpenDB

conn := clickhouse.OpenDB(&clickhouse.Options{
	Addr: []string{"127.0.0.1:9999"},
	Auth: clickhouse.Auth{
		Database: "default",
		Username: "default",
		Password: "",
	},
	TLS: &tls.Config{
		InsecureSkipVerify: true,
	},
	Settings: clickhouse.Settings{
		"max_execution_time": 60,
	},
	DialTimeout: 5 * time.Second,
	Compression: &clickhouse.Compression{
		clickhouse.CompressionLZ4,
	},
	Debug: true,
})
conn.SetMaxIdleConns(5)
conn.SetMaxOpenConns(10)
conn.SetConnMaxLifetime(time.Hour)

DSN

  • hosts - comma-separated list of single address hosts for load-balancing and failover
  • username/password - auth credentials
  • database - select the current default database
  • dial_timeout - a duration string is a possibly signed sequence of decimal numbers, each with optional fraction and a unit suffix such as "300ms", "1s". Valid time units are "ms", "s", "m".
  • connection_open_strategy - random/in_order (default random).
    • round-robin - choose a round-robin server from the set
    • in_order - first live server is chosen in specified order
  • debug - enable debug output (boolean value)
  • compress - enable lz4 compression (boolean value)

SSL/TLS parameters:

  • secure - establish secure connection (default is false)
  • skip_verify - skip certificate verification (default is false)

Example:

clickhouse://username:password@host1:9000,host2:9000/database?dial_timeout=200ms&max_execution_time=60

Benchmark

V1 (READ) V2 (READ) std V2 (READ) native
1.218s 924.390ms 675.721ms
V1 (WRITE) V2 (WRITE) std V2 (WRITE) native V2 (WRITE) by column
1.899s 1.177s 699.203ms 661.973ms

Install

go get -u github.com/ClickHouse/clickhouse-go/v2

Examples

native interface

std database/sql interface

A Note on TLS/SSL

At a low level all driver connect methods (DSN/OpenDB/Open) will use the Go tls package to establish a secure connection. The driver knows to use TLS if the Options struct contains a non-nil tls.Config pointer.

Setting secure in the DSN creates a minimal tls.Config struct with only the InsecureSkipVerify field set (either true or false). It is equivalent to this code:

conn := clickhouse.OpenDB(&clickhouse.Options{
	...
    TLS: &tls.Config{
            InsecureSkipVerify: false
	}
	...
    })

This minimal tls.Config is normally all that is necessary to connect to the secure native port (normally 9440) on a ClickHouse server. If the ClickHouse server does not have a valid certificate (expired, wrong host name, not signed by a publicly recognized root Certificate Authority), InsecureSkipVerify can be to true, but that is strongly discouraged.

If additional TLS parameters are necessary the application code should set the desired fields in the tls.Config struct. That can include specific cipher suites, forcing a particular TLS version (like 1.2 or 1.3), adding an internal CA certificate chain, adding a client certificate (and private key) if required by the ClickHouse server, and most of the other options that come with a more specialized security setup.

Third-party alternatives