# go-mysql

A pure go library to handle MySQL network protocol and replication.

## Replication

Replication package handles MySQL replication protocol like [python-mysql-replication](https://github.com/noplay/python-mysql-replication).

You can use it as a MySQL slave to sync binlog from master then do something, like updating cache, etc...

### Example

```go
import (
    "github.com/siddontang/go-mysql/replication"
    "os"
)
// Create a binlog syncer with a unique server id, the server id must be different from other MySQL's.
// flavor is mysql or mariadb
cfg := replication.BinlogSyncerConfig {
    ServerID: 100,
    Flavor:   "mysql",
    Host:     "127.0.0.1",
    Port:     3306,
    User:     "root",
    Password: "",
}
syncer := replication.NewBinlogSyncer(cfg)

// Start sync with sepcified binlog file and position
streamer, _ := syncer.StartSync(mysql.Position{binlogFile, binlogPos})

// or you can start a gtid replication like
// streamer, _ := syncer.StartSyncGTID(gtidSet)
// the mysql GTID set likes this "de278ad0-2106-11e4-9f8e-6edd0ca20947:1-2"
// the mariadb GTID set likes this "0-1-100"

for {
    ev, _ := streamer.GetEvent(context.Background())
    // Dump event
    ev.Dump(os.Stdout)
}

// or we can use a timeout context
for {
    ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
    e, _ := s.GetEvent(ctx)
    cancel()

    if err == context.DeadlineExceeded {
        // meet timeout
        continue
    }

    ev.Dump(os.Stdout)
}
```

The output looks:

```
=== RotateEvent ===
Date: 1970-01-01 08:00:00
Log position: 0
Event size: 43
Position: 4
Next log name: mysql.000002

=== FormatDescriptionEvent ===
Date: 2014-12-18 16:36:09
Log position: 120
Event size: 116
Version: 4
Server version: 5.6.19-log
Create date: 2014-12-18 16:36:09

=== QueryEvent ===
Date: 2014-12-18 16:38:24
Log position: 259
Event size: 139
Salve proxy ID: 1
Execution time: 0
Error code: 0
Schema: test
Query: DROP TABLE IF EXISTS `test_replication` /* generated by server */
```

## Canal

Canal is a package that can sync your MySQL into everywhere, like Redis, Elasticsearch.

First, canal will dump your MySQL data then sync changed data using binlog incrementally.

You must use ROW format for binlog, full binlog row image is preferred, because we may meet some errors when primary key changed in update for minimal or noblob row image.

A simple example:

```
cfg := NewDefaultConfig()
cfg.Addr = "127.0.0.1:3306"
cfg.User = "root"
// We only care table canal_test in test db
cfg.Dump.TableDB = "test"
cfg.Dump.Tables = []string{"canal_test"}

c, err := NewCanal(cfg)

type myRowsEventHandler struct {
}

func (h *myRowsEventHandler) Do(e *RowsEvent) error {
    log.Infof("%s %v\n", e.Action, e.Rows)
    return nil
}

func (h *myRowsEventHandler) String() string {
    return "myRowsEventHandler"
}

// Register a handler to handle RowsEvent
c.RegRowsEventHandler(&MyRowsEventHandler{})

// Start canal
c.Start()
```

You can see [go-mysql-elasticsearch](https://github.com/siddontang/go-mysql-elasticsearch) for how to sync MySQL data into Elasticsearch.

## Client

Client package supports a simple MySQL connection driver which you can use it to communicate with MySQL server.

### Example

```go
import (
    "github.com/siddontang/go-mysql/client"
)

// Connect MySQL at 127.0.0.1:3306, with user root, an empty passowrd and database test
conn, _ := client.Connect("127.0.0.1:3306", "root", "", "test")

conn.Ping()

// Insert
r, _ := conn.Execute(`insert into table (id, name) values (1, "abc")`)

// Get last insert id
println(r.InsertId)

// Select
r, _ := conn.Execute(`select id, name from table where id = 1`)

// Handle resultset
v, _ := r.GetInt(0, 0)
v, _ = r.GetIntByName(0, "id")
```

## Server

Server package supplies a framework to implement a simple MySQL server which can handle the packets from the MySQL client.
You can use it to build your own MySQL proxy.

### Example

```go
import (
    "github.com/siddontang/go-mysql/server"
    "net"
)

l, _ := net.Listen("tcp", "127.0.0.1:4000")

c, _ := l.Accept()

// Create a connection with user root and an empty passowrd
// We only an empty handler to handle command too
conn, _ := server.NewConn(c, "root", "", server.EmptyHandler{})

for {
    conn.HandleCommand()
}
```

Another shell

```
mysql -h127.0.0.1 -P4000 -uroot -p
//Becuase empty handler does nothing, so here the MySQL client can only connect the proxy server. :-)
```

## Failover

Failover supports to promote a new master and let other slaves replicate from it automatically when the old master was down.

Failover supports MySQL >= 5.6.9 with GTID mode, if you use lower version, e.g, MySQL 5.0 - 5.5, please use [MHA](http://code.google.com/p/mysql-master-ha/) or [orchestrator](https://github.com/outbrain/orchestrator).

At the same time, Failover supports MariaDB >= 10.0.9 with GTID mode too.

Why only GTID? Supporting failover with no GTID mode is very hard, because slave can not find the proper binlog filename and position with the new master.
Although there are many companies use MySQL 5.0 - 5.5, I think upgrade MySQL to 5.6 or higher is easy.

## Driver

Driver is the package that you can use go-mysql with go database/sql like other drivers. A simple example:

```
import (
    "database/sql"

    - "github.com/siddontang/go-mysql/driver"
)

func main() {
    // dsn format: "user:password@addr?dbname"
    dsn := "root@127.0.0.1:3306?test"
    db, _ := sql.Open(dsn)
    db.Close()
}
```

We pass all tests in https://github.com/bradfitz/go-sql-test using go-mysql driver. :-)

## Feedback

go-mysql is still in development, your feedback is very welcome.


Gmail: siddontang@gmail.com
