chclient

package module

v1.0.0 Latest Latest Go to latest Published: Oct 20, 2018 License: MIT Imports: 9 Imported by: 0

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Repository

github.com/valyala/chclient

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README ¶

chclient - fast http client for `ClickHouse`

Features

Optimized for reading large responses.
May read more than 20M rows per second on a single CPU core thanks to tsvreader.
Easily reads responses with billion rows thanks to response streaming. There is no need to fit the whole response in memory.
Works ideally with chproxy.
Sends requests to fallback address if requests to primary clickhouse address fail.

Documentation

See these docs.

Documentation ¶

Constants ¶

This section is empty.

Variables ¶

View Source

var DefaultTimeout = 30 * time.Second

DefaultTimeout is the default timeout for Client.

Functions ¶

This section is empty.

Types ¶

type Client ¶

type Client struct {
	// Addr is clickhouse address to connect to.
	//
	// localhost:8123 is used by default.
	Addr string

	// FallbackAddr is a fallback clickhouse address that is used
	// if request to Addr fails.
	//
	// By default there is no fallback address.
	FallbackAddr string

	// User to use when connecting to clickhouse.
	//
	// User is `default` if not set.
	User string

	// Password to use when connecting to clickhouse.
	//
	// Password is empty if not set.
	Password string

	// Database to use.
	//
	// Database is `default` if not set.
	Database string

	// Whether to send requests over https.
	//
	// Requests are sent over http by default.
	UseHTTPS bool

	// Whether to request compressed responses from clickhouse.
	//
	// Response compression may reduce network usage.
	//
	// Response compression is disabled by default.
	CompressResponse bool

	// Timeout is the maximum duration for the query.
	//
	// DefaultTimeout is used by default.
	Timeout time.Duration

	// URLParams to add to URL before requesting clickhouse.
	//
	// For instance,
	//
	//     Client.URLParams = []string{
	//         "default_format=Pretty",
	//         "no_cache=1",
	//     }
	URLParams []string
}

Client is http client for clickhouse.

The client is optimized for SELECT queries.

Best used with github.com/Vertamedia/chproxy.

func (*Client) Do ¶

func (c *Client) Do(query string, f ReadRowsFunc) error

Do sends the given query to clickhouse and calls f for reading query results.

The maximum query duration is limited by Client.Timeout.

f may be nil if query result isn't needed.

func (*Client) DoContext ¶

func (c *Client) DoContext(ctx context.Context, query string, f ReadRowsFunc) error

DoContext sends the given query using the given ctx to clickhouse and calls f for reading query results.

The maximum query duration may be limited with the ctx.