PHP Manual: Creates a collection

Description

public MongoCollection MongoDB::createCollection ( string $name [, array $options ] )

This method is used to create capped collections and other collections requiring special options. It is identical to running:


<?php

$collection = $db->command(array(
    "create" => $name,
    "capped" => $options["capped"],
    "size" => $options["size"],
    "max" => $options["max"],
    "autoIndexId" => $options["autoIndexId"],
));

?>

See MongoDB::command for more information about database commands.

Parameters

name

The name of the collection.

options

An array containing options for the collections. Each option is its own element in the options array, with the option name listed below being the key of the element. The supported options depend on the MongoDB server version and storage engine, and the driver passes any option that you give it straight to the server. A few of the supported options are, but you can find a full list in the MongoDB core docs on » createCollection:

capped: If the collection should be a fixed size.
size: If the collection is fixed size, its size in bytes.
max: If the collection is fixed size, the maximum number of elements to store in the collection.
autoIndexId: If capped is TRUE you can specify FALSE to disable the automatic index created on the _id field. Before MongoDB 2.2, the default value for autoIndexId was FALSE.

Return Values

Returns a collection object representing the new collection.

Examples

Example #1 MongoDB::createCollection capped collection example

A capped collection is a special type of collection that has either a fixed or a fixed number of elements. Once the collection is "full," the oldest elements will be removed when new elements are added. Capped collections can be very useful for applications like logging, where you may want to reserve a certain amount of space for logs and not worry about them getting too big.

This example creates a very tiny log collection that will keep a maximum of 10 documents.


<?php

$log = $db->createCollection(
    "logger",
    array(
        'capped' => true,
        'size' => 10*1024,
        'max' => 10
    )
);

for ($i = 0; $i < 100; $i++) {
    $log->insert(array("level" => WARN, "msg" => "sample log message #$i", "ts" => new MongoDate()));
}

$msgs = $log->find();

foreach ($msgs as $msg) {
    echo $msg['msg']."\n";
}

?>

The above example will output something similar to:

sample log message #90
sample log message #91
sample log message #92
sample log message #93
sample log message #94
sample log message #95
sample log message #96
sample log message #97
sample log message #98
sample log message #99

Changelog

Version Description

1.4.0

In versions before 1.4.0, the options were all arguments to the method. The function synopsis in those older versions is:

public MongoCollection MongoDB::createCollection ( string $name [, bool $capped = FALSE [, int $size = 0 [, int $max = 0 ]]] )

The meaning of the options is the same as described under the options argument above.