Instances of this class are used to interact with a database. To get a database:
$m = new Mongo(); // connect
$db = $m->selectDB("example");
A few unusual, but valid, database names: "null", "[x,y]", "3", "\"", "/".
Unlike collection names, database names may contain "$".
The number of servers to replicate a change to before returning success. Inherited by instances of MongoCollection derived from this. w functionality is only available in version 1.5.1+ of the MongoDB server and 1.0.8+ of the driver.
w is used whenever you perform a "safe" operation (MongoCollection::insert(), MongoCollection::update(), MongoCollection::remove(), MongoCollection::save(), and MongoCollection::ensureIndex() all support safe options). With the default value (1), a safe operation will return once the database server has the operation. If the server goes down before the operation has been replicated to a slave, it is possible to lose the operation forever. Thus, you can specify w to be higher than one and guarantee that at least one slave has the operation before it is considered successful.
For example, if w is 2, the main server and one slave must have a record of the operation or the driver will throw a MongoCursorException. It is tempting to set w to the total number of slaves + master, but then if one slave is down the op will fail and an exception will be thrown, so usually w=2 is safest (master+1 slave).
The number of milliseconds to wait for MongoDB::$w replications to take place. Inherited by instances of MongoCollection derived from this. w functionality is only available in version 1.5.1+ of the MongoDB server and 1.0.8+ of the driver.
Unless wtimeout is set, the server waits forever for replicating to w servers to finish. The driver defaults to waiting for 10 seconds, you can change this value to alter its behavior.
MongoDB core docs on » databases.
Just a note that if you use selectDB() and only select it, the database will not be created. In PHPMongoDBAdmin(http://github.com/jwage/php-mongodb-admin) I wanted a way to create a database through a form so I needed to create a dummy collection and drop it in order for the database to be created. MongoDB has a drop() method but no create() method.
Any better way to do this?