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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

database mysql mysql-server query-engine relational-database sql sql-engine sql-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 a reference implementation. Or, hop into the Dolt Discord server
[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 (
"context"
"fmt"
"time"

"github.com/dolthub/vitess/go/vt/proto/query"

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"
)

// This is an example of how to implement a MySQL server.
// After running the example, you may connect to it using the following:
//
// > 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 |
// +----------+-------------------+-------------------------------+----------------------------+
//
// The included MySQL client is used in this example, however any MySQL-compatible client will work.

var (
dbName = "mydb"
tableName = "mytable"
address = "localhost"
port = 3306
)

func main() {
pro := createTestDatabase()
engine := sqle.NewDefault(pro)

session := memory.NewSession(sql.NewBaseSession(), pro)
ctx := sql.NewContext(context.Background(), sql.WithSession(session))
ctx.SetCurrentDatabase(dbName)

// 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.NewServer(config, engine, memory.NewSessionBuilder(pro), nil)
if err != nil {
panic(err)
}
if err = s.Start(); err != nil {
panic(err)
}
}

func createTestDatabase() *memory.DbProvider {
db := memory.NewDatabase(dbName)
db.BaseDatabase.EnablePrimaryKeyIndexes()

pro := memory.NewDBProvider(db)
session := memory.NewSession(sql.NewBaseSession(), pro)
ctx := sql.NewContext(context.Background(), sql.WithSession(session))

table := memory.NewTable(db, 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.MustCreateDatetimeType(query.Type_DATETIME, 6), 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 pro
}
```

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)