(PECL mongo >=1.5.0) Returns the current element

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

(PECL mongo >=0.9.3) Runs JavaScript code on the database server [deprecated]

(PECL mongo >=1.5.0) Checks if there are results that have not yet been sent from the database

(PECL mongo >= 1.5.0) Executes a batch of write operations

(PECL mongo >=1.6.0) Set the read preference for this query