The MongoDB\BSON\ObjectId class
Guide
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BSON type for an ObjectId. The value consists of 12 bytes, where the first four bytes are a timestamp that reflect the ObjectId's creation. Specifically, the value consists of:
Intro
BSON type for an ObjectId. The value consists of 12 bytes, where the first four bytes are a timestamp that reflect the ObjectId's creation. Specifically, the value consists of:
- a 4-byte value representing the seconds since the Unix epoch,
- a 5-byte random number unique to a machine and process, and
- a 3-byte counter, starting with a random value.
In MongoDB, each document stored in a collection requires a unique _id field that acts as a primary key. If an inserted document omits the _id field, the extension automatically generates an ObjectId for the _id field.
Using ObjectIds for the _id field provides the following additional benefits:
- The creation time of the ObjectId may be accessed using the
MongoDB\BSON\ObjectId::getTimestampmethod. - Sorting on an
_idfield that stores ObjectId values is roughly equivalent to sorting by creation time.
Class synopsis
class MongoDB\BSON\ObjectId { }
Changelog
| Version | Description |
|---|---|
| PECL mongodb 1.12.0 | Implements Stringable for PHP 8.0+. |
| PECL mongodb 1.3.0 | Renamed from MongoDB\BSON\ObjectID to MongoDB\BSON\ObjectId.Implements MongoDB\BSON\ObjectIdInterface. |
| PECL mongodb 1.2.0 | Implements Serializable and JsonSerializable. |
Objectid