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https://github.com/ClickHouse/ch-go
Low-level Go Client for ClickHouse
https://github.com/ClickHouse/ch-go
binary clickhouse driver go golang protocol
Last synced: 30 days ago
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Low-level Go Client for ClickHouse
- Host: GitHub
- URL: https://github.com/ClickHouse/ch-go
- Owner: ClickHouse
- License: apache-2.0
- Created: 2021-11-14T21:37:40.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2024-10-21T12:21:27.000Z (about 2 months ago)
- Last Synced: 2024-10-21T18:13:30.313Z (about 2 months ago)
- Topics: binary, clickhouse, driver, go, golang, protocol
- Language: Go
- Homepage:
- Size: 2.06 MB
- Stars: 322
- Watchers: 11
- Forks: 50
- Open Issues: 18
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Authors: AUTHORS
Awesome Lists containing this project
- awesome-clickhouse - ClickHouse/ch-go - A low-level TCP client for the ClickHouse database implemented in Go. (Language bindings / Golang)
README
# ch [](https://pkg.go.dev/github.com/ClickHouse/ch-go#section-documentation)
Low level TCP [ClickHouse](https://clickhouse.com/) client and protocol implementation in Go. Designed for very fast data block streaming with low network, cpu and memory overhead.
NB: **No pooling, reconnects** and **not** goroutine-safe by default, only single connection.
Use [clickhouse-go](https://github.com/ClickHouse/clickhouse-go) for high-level `database/sql`-compatible client,
pooling for ch-go is available as [chpool](https://pkg.go.dev/github.com/ClickHouse/ch-go/chpool) package.
* [Feedback](https://github.com/ClickHouse/ch-go/discussions/6)
* [Benchmarks](https://github.com/go-faster/ch-bench#benchmarks)
* [Protocol reference](https://go-faster.org/docs/clickhouse)
*[ClickHouse](https://clickhouse.com/) is an open-source, high performance columnar OLAP database management system for real-time analytics using SQL.*
```console
go get github.com/ClickHouse/ch-go@latest
```
## Example
```go
package main
import (
"context"
"fmt"
"github.com/ClickHouse/ch-go"
"github.com/ClickHouse/ch-go/proto"
)
func main() {
ctx := context.Background()
c, err := ch.Dial(ctx, ch.Options{Address: "localhost:9000"})
if err != nil {
panic(err)
}
var (
numbers int
data proto.ColUInt64
)
if err := c.Do(ctx, ch.Query{
Body: "SELECT number FROM system.numbers LIMIT 500000000",
Result: proto.Results{
{Name: "number", Data: &data},
},
// OnResult will be called on next received data block.
OnResult: func(ctx context.Context, b proto.Block) error {
numbers += len(data)
return nil
},
}); err != nil {
panic(err)
}
fmt.Println("numbers:", numbers)
}
```
```
393ms 0.5B rows 4GB 10GB/s 1 job
874ms 2.0B rows 16GB 18GB/s 4 jobs
```
### Results
To stream query results, set `Result` and `OnResult` fields of [Query](https://pkg.go.dev/github.com/ClickHouse/ch-go#Query).
The `OnResult` will be called after `Result` is filled with received data block.
The `OnResult` is optional, but query will fail if more than single block is received, so it is ok to solely set the `Result`
if only one row is expected.
#### Automatic result inference
```go
var result proto.Results
q := ch.Query{
Body: "SELECT * FROM table",
Result: result.Auto(),
}
```
#### Single result with column name inference
```go
var res proto.ColBool
q := ch.Query{
Body: "SELECT v FROM test_table",
Result: proto.ResultColumn{Data: &res},
}
```
### Writing data
See [examples/insert](./examples/insert).
For table
```sql
CREATE TABLE test_table_insert
(
ts DateTime64(9),
severity_text Enum8('INFO'=1, 'DEBUG'=2),
severity_number UInt8,
body String,
name String,
arr Array(String)
) ENGINE = Memory
```
We prepare data block for insertion as follows:
```go
var (
body proto.ColStr
name proto.ColStr
sevText proto.ColEnum
sevNumber proto.ColUInt8
ts = new(proto.ColDateTime64).WithPrecision(proto.PrecisionNano) // DateTime64(9)
arr = new(proto.ColStr).Array() // Array(String)
now = time.Date(2010, 1, 1, 10, 22, 33, 345678, time.UTC)
)
// Append 10 rows to initial data block.
for i := 0; i < 10; i++ {
body.AppendBytes([]byte("Hello"))
ts.Append(now)
name.Append("name")
sevText.Append("INFO")
sevNumber.Append(10)
arr.Append([]string{"foo", "bar", "baz"})
}
input := proto.Input{
{Name: "ts", Data: ts},
{Name: "severity_text", Data: &sevText},
{Name: "severity_number", Data: sevNumber},
{Name: "body", Data: body},
{Name: "name", Data: name},
{Name: "arr", Data: arr},
}
```
#### Single data block
```go
if err := conn.Do(ctx, ch.Query{
// Or "INSERT INTO test_table_insert (ts, severity_text, severity_number, body, name, arr) VALUES"
// Or input.Into("test_table_insert")
Body: "INSERT INTO test_table_insert VALUES",
Input: input,
}); err != nil {
panic(err)
}
```
### Stream data
```go
// Stream data to ClickHouse server in multiple data blocks.
var blocks int
if err := conn.Do(ctx, ch.Query{
Body: input.Into("test_table_insert"), // helper that generates INSERT INTO query with all columns
Input: input,
// OnInput is called to prepare Input data before encoding and sending
// to ClickHouse server.
OnInput: func(ctx context.Context) error {
// On OnInput call, you should fill the input data.
//
// NB: You should reset the input columns, they are
// not reset automatically.
//
// That is, we are re-using the same input columns and
// if we will return nil without doing anything, data will be
// just duplicated.
input.Reset() // calls "Reset" on each column
if blocks >= 10 {
// Stop streaming.
//
// This will also write tailing input data if any,
// but we just reset the input, so it is currently blank.
return io.EOF
}
// Append new values:
for i := 0; i < 10; i++ {
body.AppendBytes([]byte("Hello"))
ts.Append(now)
name.Append("name")
sevText.Append("DEBUG")
sevNumber.Append(10)
arr.Append([]string{"foo", "bar", "baz"})
}
// Data will be encoded and sent to ClickHouse server after returning nil.
// The Do method will return error if any.
blocks++
return nil
},
}); err != nil {
panic(err)
}
```
### Writing dumps in Native format
You can use `ch-go` to write ClickHouse dumps in [Native][native] format:
> The most efficient format. Data is written and read by blocks in binary format. For each block, the number of rows,
> number of columns, column names and types, and parts of columns in this block are recorded one after another.
> In other words, this format is “columnar” – it does not convert columns to rows.
> This is the format used in the native interface for interaction between servers,
> for using the command-line client, and for C++ clients.
[native]: https://clickhouse.com/docs/en/interfaces/formats/#native
See [./internal/cmd/ch-native-dump](./internal/cmd/ch-native-dump/main.go) for more sophisticated example.
Example:
```go
var (
colK proto.ColInt64
colV proto.ColInt64
)
// Generate some data.
for i := 0; i < 100; i++ {
colK.Append(int64(i))
colV.Append(int64(i) + 1000)
}
// Write data to buffer.
var buf proto.Buffer
input := proto.Input{
{"k", colK},
{"v", colV},
}
b := proto.Block{
Rows: colK.Rows(),
Columns: len(input),
}
// Note that we are using version 54451, proto.Version will fail.
if err := b.EncodeRawBlock(&buf, 54451, input); err != nil {
panic(err)
}
// You can write buf.Buf to io.Writer, e.g. os.Stdout or file.
var out bytes.Buffer
_, _ = out.Write(buf.Buf)
// You can encode multiple buffers in sequence.
//
// To do this, reset buf and all columns, append new values
// to columns and call EncodeRawBlock again.
buf.Reset()
colK.Reset()
colV.Reset()
```
## Features
* OpenTelemetry support
* No reflection or `interface{}`
* Generics (go1.18) for `Array[T]`, `LowCardinaliy[T]`, `Map[K, V]`, `Nullable[T]`
* [Reading or writing](#dumps) ClickHouse dumps in `Native` format
* **Column**-oriented design that operates directly with **blocks** of data
* [Dramatically more efficient](https://github.com/ClickHouse/ch-bench)
* Up to 100x faster than row-first design around `sql`
* Up to 700x faster than HTTP API
* Low memory overhead (data blocks are slices, i.e. continuous memory)
* Highly efficient input and output block streaming
* As close to ClickHouse as possible
* Structured query execution telemetry streaming
* Query progress
* Profiles
* Logs
* [Profile events](https://github.com/ClickHouse/ClickHouse/issues/26177)
* LZ4, ZSTD or *None* (just checksums for integrity check) compression
* [External data](https://clickhouse.com/docs/en/engines/table-engines/special/external-data/) support
* Rigorously tested
* Windows, Mac, Linux (also x86)
* Unit tests for encoding and decoding
* ClickHouse **Server** in **Go** for faster tests
* Golden files for all packets, columns
* Both server and client structures
* Ensuring that partial read leads to failure
* End-to-end [tests](.github/workflows/e2e.yml) on multiple LTS and stable versions
* Fuzzing
## Supported types
* UInt8, UInt16, UInt32, UInt64, UInt128, UInt256
* Int8, Int16, Int32, Int64, Int128, Int256
* Date, Date32, DateTime, DateTime64
* Decimal32, Decimal64, Decimal128, Decimal256 (only low-level raw values)
* IPv4, IPv6
* String, FixedString(N)
* UUID
* Array(T)
* Enum8, Enum16
* LowCardinality(T)
* Map(K, V)
* Bool
* Tuple(T1, T2, ..., Tn)
* Nullable(T)
* Point
* Nothing, Interval
## Enums
You can use automatic enum inference in `proto.ColEnum`, this will come with some performance penalty.
To use `proto.ColEnum8` and `proto.ColEnum16`, you need to explicitly provide DDL for them via `proto.Wrap`:
```go
var v proto.ColEnum8
const ddl = `'Foo'=1, 'Bar'=2, 'Baz'=3`
input := []proto.InputColumn{
{Name: "v", Data: proto.Wrap(&v, ddl)},
}
```
## Generics
Most columns implement [proto.ColumnOf\[T\]](https://pkg.go.dev/github.com/ClickHouse/ch-go/proto#ColumnOf) generic constraint:
```go
type ColumnOf[T any] interface {
Column
Append(v T)
AppendArr(vs []T)
Row(i int) T
}
```
For example, [ColStr](https://pkg.go.dev/github.com/ClickHouse/ch-go/proto#ColStr) (and [ColStr.LowCardinality](https://pkg.go.dev/github.com/ClickHouse/ch-go/proto#ColStr.LowCardinality)) implements `ColumnOf[string]`.
Same for arrays: `new(proto.ColStr).Array()` implements `ColumnOf[[]string]`, column of `[]string` values.
### Array
Generic for `Array(T)`
```go
// Array(String)
arr := proto.NewArray[string](new(proto.ColStr))
// Or
arr := new(proto.ColStr).Array()
q := ch.Query{
Body: "SELECT ['foo', 'bar', 'baz']::Array(String) as v",
Result: arr.Results("v"),
}
// Do ...
arr.Row(0) // ["foo", "bar", "baz"]
```
## Dumps
### Reading
Use `proto.Block.DecodeRawBlock` on `proto.NewReader`:
```go
func TestDump(t *testing.T) {
// Testing decoding of Native format dump.
//
// CREATE TABLE test_dump (id Int8, v String)
// ENGINE = MergeTree()
// ORDER BY id;
//
// SELECT * FROM test_dump
// ORDER BY id
// INTO OUTFILE 'test_dump_native.raw' FORMAT Native;
data, err := os.ReadFile(filepath.Join("_testdata", "test_dump_native.raw"))
require.NoError(t, err)
var (
dec proto.Block
ids proto.ColInt8
values proto.ColStr
)
require.NoError(t, dec.DecodeRawBlock(
proto.NewReader(bytes.NewReader(data)),
proto.Results{
{Name: "id", Data: &ids},
{Name: "v", Data: &values},
}),
)
}
```
### Writing
Use `proto.Block.EncodeRawBlock` with version `54451` on `proto.Buffer` with `Rows` and `Columns` set:
```go
func TestLocalNativeDump(t *testing.T) {
ctx := context.Background()
// Testing clickhouse-local.
var v proto.ColStr
for _, s := range data {
v.Append(s)
}
buf := new(proto.Buffer)
b := proto.Block{Rows: 2, Columns: 2}
require.NoError(t, b.EncodeRawBlock(buf, 54451, []proto.InputColumn{
{Name: "title", Data: v},
{Name: "data", Data: proto.ColInt64{1, 2}},
}), "encode")
dir := t.TempDir()
inFile := filepath.Join(dir, "data.native")
require.NoError(t, os.WriteFile(inFile, buf.Buf, 0600), "write file")
cmd := exec.Command("clickhouse-local", "local",
"--logger.console",
"--log-level", "trace",
"--file", inFile,
"--input-format", "Native",
"--output-format", "JSON",
"--query", "SELECT * FROM table",
)
out := new(bytes.Buffer)
errOut := new(bytes.Buffer)
cmd.Stdout = out
cmd.Stderr = errOut
t.Log(cmd.Args)
require.NoError(t, cmd.Run(), "run: %s", errOut)
t.Log(errOut)
v := struct {
Rows int `json:"rows"`
Data []struct {
Title string `json:"title"`
Data int `json:"data,string"`
}
}{}
require.NoError(t, json.Unmarshal(out.Bytes(), &v), "json")
assert.Equal(t, 2, v.Rows)
if assert.Len(t, v.Data, 2) {
for i, r := range []struct {
Title string `json:"title"`
Data int `json:"data,string"`
}{
{"Foo", 1},
{"Bar", 2},
} {
assert.Equal(t, r, v.Data[i])
}
}
}
```
## TODO
- [ ] Types
- [ ] [Decimal(P, S)](https://clickhouse.com/docs/en/sql-reference/data-types/decimal/) API
- [ ] JSON
- [ ] SimpleAggregateFunction
- [ ] AggregateFunction
- [x] Nothing
- [x] Interval
- [ ] Nested
- [ ] [Geo types](https://clickhouse.com/docs/en/sql-reference/data-types/geo/)
- [x] Point
- [ ] Ring
- [ ] Polygon
- [ ] MultiPolygon
- [ ] Improved i/o timeout handling for reading packets from server
- [ ] Close connection on context cancellation in all cases
- [ ] Ensure that reads can't block forever
## Reference
* [clickhouse-cpp](https://github.com/ClickHouse/clickhouse-cpp)
* [clickhouse-go](https://github.com/ClickHouse/clickhouse-go)
* [python driver](https://github.com/mymarilyn/clickhouse-driver)
## License
Apache License 2.0