(PECL mongo >= 0.8.3) Creates a new code object

(PECL mongo >=1.1.0) Returns the address being used by this for slaveOkay reads

(PECL mongo >=0.9.0) The name of this database

(PECL mongo >=1.3.0) Perform an aggregation using the aggregation framework

(PECL mongo >=1.0.11) Limits the number of elements returned in one batch.

(PECL mongo >= 1.5.0) Adds a write operation to a batch