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.

Some of the features:

• Mnesia style transactions:
  • Nested transactions are implemented using savepoints.
  • Transactions are automatically retried when deadlocks are detected.
• 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.
• Slow queries are interrupted without killing 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.

Synopsis

%% Connect
{ok, Pid} = mysql:start_link([{host, "localhost"}, {user, "foo"},
                              {password, "hello"}, {database, "test"}]),

%% 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),

Usage as a dependency

With erlang.mk:

PROJECT = someproject
DEPS = mysql-otp
dep_mysql-otp = git https://github.com/mysql-otp/mysql-otp master
include erlang.mk

With rebar:

{deps, [
    {mysql, ".*", {git, "https://github.com/mysql-otp/mysql-otp",
                   {branch, "master"}}}
]}.

Tests

Run the eunit tests with make eunit. The tests need an executable rebar in the $PATH. 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!