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https://github.com/dolthub/go-mysql-server

A MySQL-compatible relational database with a storage agnostic query engine. Implemented in pure Go.
https://github.com/dolthub/go-mysql-server

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A MySQL-compatible relational database with a storage agnostic query engine. Implemented in pure Go.

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# A MySQL compatible database engine written in pure Go



**go-mysql-server** is a data-source agnostic SQL engine and server

which runs queries on data sources you provide, using the MySQL

dialect and wire protocol. A simple in-memory database implementation

is included, and you can query any data source you want by

implementing your own backend.



[Dolt](https://www.doltdb.com), a SQL database with Git-style

versioning, is the main production database implementation of this

package.  [Check

out](https://docs.dolthub.com/introduction/what-is-dolt) that project

for reference a implementation. Or, hop into the Dolt discord

[here](https://discord.com/invite/RFwfYpu) if you want to talk to the

[core developers](https://www.dolthub.com/team) behind

**go-mysql-server** and Dolt.



## Compatibility



With the exception of specific limitations (see below),

**go-mysql-server** is a drop-in replacement for MySQL. Any client

library, tool, query, SQL syntax, SQL function, etc. that works with

MySQL should also work with **go-mysql-server**. If you find a gap in

functionality, please file an issue.



For full MySQL compatibility documentation, see the [Dolt

docs](https://docs.dolthub.com/sql-reference/sql-support) on this

topic.



## Scope of this project



- SQL server and engine to query your data sources.

- In-memory database backend implementation suitable for use in tests.

- Interfaces you can use to implement new backends to query your own

  data sources.

- With a few caveats and using a full database implementation, a

  drop-in MySQL database replacement.



**go-mysql-server** has two primary uses case:



1. Stand-in for MySQL in a golang test environment, using the built-in

   `memory` database implementation.



2. Providing access to arbitrary data sources with SQL queries by

   implementing a handful of interfaces. The most complete real-world

   implementation is [Dolt](https://github.com/dolthub/dolt).



## Installation



Add **go-mysql-server** as a dependency to your project. In the

directory with the `go.mod` file, run:



```

go get github.com/dolthub/go-mysql-server@latest

```



## Using the in-memory test server



The in-memory test server can replace a real MySQL server in

tests. Start the server using the code in the [_example

directory](_example/main.go), also reproduced below.



```go



package main



import (

	"fmt"

	"time"



	sqle "github.com/dolthub/go-mysql-server"

	"github.com/dolthub/go-mysql-server/memory"

	"github.com/dolthub/go-mysql-server/server"

	"github.com/dolthub/go-mysql-server/sql"

	"github.com/dolthub/go-mysql-server/sql/types"

)



var (

	dbName    = "mydb"

	tableName = "mytable"

	address   = "localhost"

	port      = 3306

)



func main() {

	ctx := sql.NewEmptyContext()

	engine := sqle.NewDefault(

		memory.NewDBProvider(

			createTestDatabase(ctx),

		))



	// This variable may be found in the "users_example.go" file. Please refer to that file for a walkthrough on how to

	// set up the "mysql" database to allow user creation and user checking when establishing connections. This is set

	// to false for this example, but feel free to play around with it and see how it works.

	if enableUsers {

		if err := enableUserAccounts(ctx, engine); err != nil {

			panic(err)

		}

	}



	config := server.Config{

		Protocol: "tcp",

		Address:  fmt.Sprintf("%s:%d", address, port),

	}

	s, err := server.NewDefaultServer(config, engine)

	if err != nil {

		panic(err)

	}

	if err = s.Start(); err != nil {

		panic(err)

	}

}



func createTestDatabase(ctx *sql.Context) *memory.Database {

	db := memory.NewDatabase(dbName)

	db.EnablePrimaryKeyIndexes()

	table := memory.NewTable(tableName, sql.NewPrimaryKeySchema(sql.Schema{

		{Name: "name", Type: types.Text, Nullable: false, Source: tableName, PrimaryKey: true},

		{Name: "email", Type: types.Text, Nullable: false, Source: tableName, PrimaryKey: true},

		{Name: "phone_numbers", Type: types.JSON, Nullable: false, Source: tableName},

		{Name: "created_at", Type: types.Datetime, Nullable: false, Source: tableName},

	}), db.GetForeignKeyCollection())

	db.AddTable(tableName, table)



	creationTime := time.Unix(0, 1667304000000001000).UTC()

	_ = table.Insert(ctx, sql.NewRow("Jane Deo", "[email protected]", types.MustJSON(`["556-565-566", "777-777-777"]`), creationTime))

	_ = table.Insert(ctx, sql.NewRow("Jane Doe", "[email protected]", types.MustJSON(`[]`), creationTime))

	_ = table.Insert(ctx, sql.NewRow("John Doe", "[email protected]", types.MustJSON(`["555-555-555"]`), creationTime))

	_ = table.Insert(ctx, sql.NewRow("John Doe", "[email protected]", types.MustJSON(`[]`), creationTime))

	return db

}

```



This example populates the database by creating `memory.Database` and

`memory.Table` objects via golang code, but you can also populate it

by issuing `CREATE DATABASE`, `CREATE TABLE`, etc. statements to the

server once it's running.



Once the server is running, connect with any MySQL client, including

the golang MySQL connector and the `mysql` shell.



```bash

> mysql --host=localhost --port=3306 --user=root mydb --execute="SELECT * FROM mytable;"

+----------+-------------------+-------------------------------+----------------------------+

| name     | email             | phone_numbers                 | created_at                 |

+----------+-------------------+-------------------------------+----------------------------+

| Jane Deo | [email protected] | ["556-565-566","777-777-777"] | 2022-11-01 12:00:00.000001 |

| Jane Doe | [email protected]      | []                            | 2022-11-01 12:00:00.000001 |

| John Doe | [email protected]      | ["555-555-555"]               | 2022-11-01 12:00:00.000001 |

| John Doe | [email protected]   | []                            | 2022-11-01 12:00:00.000001 |

+----------+-------------------+-------------------------------+----------------------------+

```



## Limitations of the in-memory database implementation



The in-memory database implementation included with this package is

intended for use in tests. It has specific limitations that we know

of:



- [Not

  threadsafe](https://github.com/dolthub/go-mysql-server/issues/1306). To

  avoid concurrency issues, limit DDL and DML statements (`CREATE

  TABLE`, `INSERT`, etc.) to a single goroutine.

- [No transaction

  support](https://github.com/dolthub/go-mysql-server/issues/1506). Statements

  like `START TRANSACTION`, `ROLLBACK`, and `COMMIT` are no-ops.

- [Non-performant index

  implementation](https://github.com/dolthub/go-mysql-server/issues/1347). Indexed

  lookups and joins perform full table scans on the underlying tables.



## Custom backend implementations



You can create your own backend to query your own data sources by

implementing some interfaces. For detailed instructions, see the

[backend guide](./BACKEND.md).



## Technical documentation for contributors and backend developers



- [Architecture](./ARCHITECTURE.md) is an overview of the various

  packages of the project and how they fit together.

- [Contribution guide](./CONTRIBUTING.md) for new contributors,

  including instructions for how to get your PR merged.



## Powered by go-mysql-server



* [dolt](https://github.com/dolthub/dolt)

* [gitbase](https://github.com/src-d/gitbase) (defunct)



Are you building a database backend using **go-mysql-server**? We

would like to hear from you and include you in this list.



## Security Policy



[go-mysql-server's security

policy](https://github.com/dolthub/go-mysql-server/blob/main/SECURITY.md) is

maintained in this repository. Please follow the disclosure instructions there.

Please do not initially report security issues in this repository's public

GitHub issues.



## Acknowledgements



**go-mysql-server** was originally developed by the `{source-d}`

organzation, and this repository was originally forked from

[src-d](https://github.com/src-d/go-mysql-server). We want to thank

the entire `{source-d}` development team for their work on this

project, especially Miguel Molina (@erizocosmico) and Juanjo Álvarez

Martinez (@juanjux).



## License



Apache License 2.0, see [LICENSE](/LICENSE)