mysql-otp

MySQL/OTP

MySQL/OTP is a driver for connecting Erlang/OTP applications to MySQL databases. It is a native implementation of the MySQL protocol in Erlang.

Features:

• Nestable Mnesia style transactions.
  • Nested transactions are implemented using savepoints (since 0.6.0).
  • Currenly transactions are not automatically retried when deadlocks are detected but there are plans to implement that too. See #7.)
• Uses the binary protocol for prepared statements.
• Each connection is a gen_server, which makes it compatible with Poolboy (for connection pooling) and ordinary OTP supervisors.
• No records in the public API.
• Query timeouts don't kill the connection (MySQL version ≥ 5.0.0).

See also:

• API documenation (Edoc)
• Test coverage (EUnit)
• Why another MySQL driver? in the wiki

This is a work in progress. Use a tagged version to make sure nothing breaks.

Todo:

• Ping regularily when inactive
• Retry transactions when deadlocks are detected

Synopsis

Opts = [{host, "localhost"}, {user, "foo"}, {password, "hello"},
        {database, "test"}],

%% Connect
{ok, Pid} = mysql:start_link(Opts),

%% Select
{ok, ColumnNames, Rows} =
    mysql:query(Pid, <<"SELECT * FROM mytable WHERE id = ?">>, [1]),

%% Manipulate data
ok = mysql:query(Pid, "INSERT INTO mytable (id, bar) VALUES (?, ?)", [1, 42]),

%% Separate calls to fetch more info about the last query
LastInsertId = mysql:insert_id(Pid),
AffectedRows = mysql:affected_rows(Pid),
WarningCount = mysql:warning_count(Pid),

%% Mnesia style transaction (nestable)
Result = mysql:transaction(Pid, fun () ->
    ok = mysql:query(Pid, "INSERT INTO mytable (foo) VALUES (1)"),
    throw(foo),
    ok = mysql:query(Pid, "INSERT INTO mytable (foo) VALUES (1)")
end),
case Result of
    {atomic, ResultOfFun} ->
        io:format("Inserted 2 rows.~n");
    {aborted, Reason} ->
        io:format("Inserted 0 rows.~n")
end

%% Graceful timeout handling: SLEEP() returns 1 when interrupted
{ok, [<<"SLEEP(5)">>], [[1]]} =
    mysql:query(Pid, <<"SELECT SLEEP(5)">>, 1000),

Tests

Run the eunit tests with rebar eunit. For the suite mysql_tests you need MySQL running on localhost and give privileges to the otptest user:

grant all privileges on otptest.* to otptest@localhost identified by 'otptest';

Contributing

Pull request and feature requests are welcome. If you're looking for something to do, pick one of the issues and solve it. Remember to include test cases.

License

GNU Lesser General Public License (LGPL) version 3 or any later version. Since the LGPL is a set of additional permissions on top of the GPL, both license texts are included in the files COPYING and COPYING.LESSER respectively.

We hope this license should be permissive enough while remaining copyleft. If you're having issues with this license, please create an issue in the issue tracker!