harnish / go-mysql-server

An extensible MySQL server implementation in Go.

go-mysql-server

go-mysql-server is a standard SQL parser based on MySQL syntax, that is able to resolve and optimize queries. It provides simple interfaces to allow you to implement any tabular data source.

go-mysql-server also provides a server implementation compatible with the MySQL wire protocol. That means it is compatible with MySQL ODBC, JDBC, or the default MySQL client shell interface.

Installation

The import path for the package is gopkg.in/src-d/go-mysql-server.v0.

To install it, run:

go get gopkg.in/src-d/go-mysql-server.v0

Documentation

• go-mysql-server godoc

SQL syntax

We are continuously adding more functionality to go-mysql-server. We support a subset of what is supported in MySQL, currently including:

	Supported
Comparison expressions	!=, ==, >, <, >=,<=, BETWEEN, REGEXP, IN, NOT IN
Null check expressions	IS NULL, IS NOT NULL
Grouping expressions	COUNT, MIN, MAX ,AVG
Standard expressions	ALIAS, LITERAL, STAR (*)
Statements	CROSS JOIN, INNER JOIN, DESCRIBE, FILTER (WHERE), GROUP BY, LIMIT/OFFSET, SELECT, SHOW TABLES, SORT, DISTINCT, CREATE TABLE, INSERT
Functions	SUBSTRING, ARRAY_LENGTH
Time functions	YEAR, MONTH, DAY, HOUR, MINUTE, SECOND, DAYOFYEAR

Custom functions

• IS_BINARY(blob): returns whether a BLOB is a binary file or not.
• SUBSTRING(str,pos), SUBSTRING(str,pos,len): return a substring from the provided string.
• Date and Timestamp functions: YEAR(date), MONTH(date), DAY(date), HOUR(date), MINUTE(date), SECOND(date), DAYOFYEAR(date).
• ARRAY_LENGTH(json): If the json representation is an array, this function returns its size.

Example

go-mysql-server contains a SQL engine and server implementation. So, if you want to start a server, first instantiate the engine and pass your sql.Database implementation.

It will be in charge of handling all the logic to retrieve the data from your source. Here you can see an example using the in-memory database implementation:

...

func main() {
    driver := sqle.New()
    driver.AddDatabase(createTestDatabase())

    auth := mysql.NewAuthServerStatic()
    auth.Entries["user"] = []*mysql.AuthServerStaticEntry{{
        Password: "pass",
    }}

    config := server.Config{
        Protocol: "tcp",
        Address:  "localhost:3306",
        Auth:     auth,
    }

    s, err := server.NewDefaultServer(config, driver)
    if err != nil {
        panic(err)
    }

    s.Start()
}

func createTestDatabase() *mem.Database {
    const (
        dbName    = "test"
        tableName = "mytable"
    )

    db := mem.NewDatabase(dbName)
    table := mem.NewTable(tableName, sql.Schema{
        {Name: "name", Type: sql.Text, Nullable: false, Source: tableName},
        {Name: "email", Type: sql.Text, Nullable: false, Source: tableName},
        {Name: "phone_numbers", Type: sql.JSON, Nullable: false, Source: tableName},
        {Name: "created_at", Type: sql.Timestamp, Nullable: false, Source: tableName},
    })

    db.AddTable(tableName, table)
    table.Insert(sql.NewRow("John Doe", "[email protected]", []string{"555-555-555"}, time.Now()))
    table.Insert(sql.NewRow("John Doe", "[email protected]", []string{}, time.Now()))
    table.Insert(sql.NewRow("Jane Doe", "[email protected]", []string{}, time.Now()))
    table.Insert(sql.NewRow("Evil Bob", "[email protected]", []string{"555-666-555", "666-666-666"}, time.Now()))
    return db
}

...

Then, you can connect to the server with any MySQL client:

> mysql --host=127.0.0.1 --port=3306 -u user -ppass db -e "SELECT * FROM mytable"
+----------+-------------------+-------------------------------+---------------------+
| name     | email             | phone_numbers                 | created_at          |
+----------+-------------------+-------------------------------+---------------------+
| John Doe | [email protected]      | ["555-555-555"]               | 2018-04-18 10:42:58 |
| John Doe | [email protected]   | []                            | 2018-04-18 10:42:58 |
| Jane Doe | [email protected]      | []                            | 2018-04-18 10:42:58 |
| Evil Bob | [email protected] | ["555-666-555","666-666-666"] | 2018-04-18 10:42:58 |
+----------+-------------------+-------------------------------+---------------------+

See the complete example here.

Queries examples

SELECT count(name) FROM mytable
+---------------------+
| COUNT(mytable.name) |
+---------------------+
|                   4 |
+---------------------+

SELECT name,year(created_at) FROM mytable
+----------+--------------------------+
| name     | YEAR(mytable.created_at) |
+----------+--------------------------+
| John Doe |                     2018 |
| John Doe |                     2018 |
| Jane Doe |                     2018 |
| Evil Bob |                     2018 |
+----------+--------------------------+

SELECT email FROM mytable WHERE name = 'Evil Bob'
+-------------------+
| email             |
+-------------------+
| [email protected] |
+-------------------+

Custom data source implementation

To be able to create your own data source implementation you need to implement the following interfaces:

• sql.Database interface. This interface will provide tables from your data source.

  • If your database implementation supports adding more tables, you might want to add support for sql.Alterable interface

• sql.Table interface. It will be in charge of transforming any kind of data into an iterator of Rows. Depending on how much you want to optimize the queries, you also can implement other interfaces on your tables:

  • sql.PushdownProjectionTable interface will provide a way to get only the columns needed for the executed query.
  • sql.PushdownProjectionAndFiltersTable interface will provide the same functionality described before, but also will push down the filters used in the executed query. It allows to filter data in advance, and speed up queries.
  • sql.Indexable add index capabilities to your table. By implementing this interface you can create and use indexes on this table.
  • sql.Inserter can be implemented if your data source tables allow insertions.

• If you need some custom tree modifications, you can also implement your own analyzer.Rules.

You can see a really simple data source implementation on our mem package.

Powered by go-mysql-server

• gitbase

License

Apache License 2.0, see LICENSE