Store 'mysql'

This module is compiled in when MySQL 3 or 4 is available. This store provides storage using the MySQL open source database including contexts. It was added in Redland 0.9.15. It has however been tested with several million triples and deployed.

There are several options required with the mysql storage in order to connect to the database. These are:

  • host for the database server hostname

  • port for the database server port (defaults to the MySQL port 3306 if not given)

  • database for the MySQL database name (not the storage name)

  • user for the database server user name

  • password for the database server password

NOTE: Take care exposing the password as for example, program arguments or environment variables. The rdfproc utility can with help this by reading the password from standard input. Inside programs, one way to prevent storing the password in a string is to construct a Redland hash of the storage options such as via librdf_hash_from_string and use librdf_new_storage_with_options to create a storage. The rdfproc utility source code demonstrates this.

The storage name parameter given to the storage constructor librdf_new_storage is used inside the mysql store to allow multiple stores inside one MySQL database instance as parameterised with the above options.

If boolean option new is given, any existing MySQL database named by the storage option database, say db will be dropped and the appropriate new tables created. The MySQL database db must already exist, such as made with the MySQL create database db command and the appropriate privileges set so that the user and password work.

If boolean option reconnect is given, MySQL reconnection will be enabled so that if the database connection is dropped, MySQL will attempt to reconnect.

This store always provides contexts; the boolean storage option contexts is not checked.

Examples:

  /* A new MySQL store */
  storage=librdf_new_storage(world, "mysql", "db1",
      "new='yes',host='localhost',database='red',user='foo','password='bar'");

  /* A different, existing MySQL store db2 in the same database as above */
  storage=librdf_new_storage(world, "mysql", "db2",
      "host='localhost',database='red',user='foo','password='bar'");

  /* An existing MySQL store on a different database server */
  storage=librdf_new_storage(world, "mysql", "db3",
      "host='db.example.org',database='abc',user='baz','password='blah'");

  /* Opening with an options hash */
  options=librdf_new_hash(world, NULL);
  librdf_hash_from_string(options, 
      "host='db.example.org',database='abc',user='baz'");
  librdf_hash_put_strings(options, "password", user_password);
  storage=librdf_new_storage_with_options(world, "mysql", "db4", options);

In PHP:

  # An existing store
  $storage=librdf_new_storage($world, 'mysql', 'db4', 
      "host='127.0.0.1',database='xyz',user='foo',password='blah'");

Summary:

  • Persistent

  • Suitable for very large models

  • Indexed but not optimized

  • Smaller disk usage than BDB

  • Possibility of free text searching

  • Contexts always provided



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