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MongoDB Inc
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BSON::OID - BSON type wrapper for Object IDs


version v1.6.4


    use BSON::Types ':all';

    my $oid  = bson_oid();
    my $oid  = bson_oid->from_epoch(1467543496, 0); # for queries only

    my $bytes = $oid->oid;
    my $hex   = $oid->hex;


This module provides a wrapper around a BSON Object ID.



A 12-byte (packed) Object ID (OID) string. If not provided, a new OID will be generated.



    my $oid = BSON::OID->new;

    my $oid = BSON::OID->new( oid => $twelve_bytes );

This is the preferred way to generate an OID. Without arguments, a unique OID will be generated. With a 12-byte string, an object can be created around an existing OID byte-string.


    # generate a new OID

    my $oid = BSON::OID->from_epoch( $epoch, 0); # other bytes zeroed
    my $oid = BSON::OID->from_epoch( $epoch, $eight_more_bytes );

    # reset an existing OID

    $oid->from_epoch( $new_epoch, 0 );
    $oid->from_epoch( $new_epoch, $eight_more_bytes );

Warning! You should not rely on this method for a source of unique IDs. Use this method for query boundaries, only.

An OID is a twelve-byte string. Typically, the first four bytes represent integer seconds since the Unix epoch in big-endian format. The remaining bytes ensure uniqueness.

With this method, the first argument to this method is an epoch time (in integer seconds). The second argument is the remaining eight-bytes to append to the string.

When called as a class method, it returns a new BSON::OID object. When called as an object method, it mutates the existing internal OID value.

As a special case, if the second argument is defined and zero ("0"), then the remaining bytes will be zeroed.

    my $oid = BSON::OID->from_epoch(1467545180, 0);

This is particularly useful when looking for documents by their insertion date: you can simply look for OIDs which are greater or lower than the one generated with this method.

For backwards compatibility with Mango, if called without a second argument, the method generates the remainder of the fields "like usual". This is equivalent to calling BSON::OID->new and replacing the first four bytes with the packed epoch value.

    # UNSAFE: don't do this unless you have to

    my $oid = BSON::OID->from_epoch(1467545180);

If you insist on creating a unique OID with from_epoch, set the remaining eight bytes in a way that guarantees thread-safe uniqueness, such as from a reliable source of randomness (see Crypt::URandom).

  use Crypt::Random 'urandom';
  my $oid = BSON::OID->from_epoch(1467545180, urandom(8));


Returns the oid attributes as 24-byte hexadecimal value


Returns a number corresponding to the portion of the oid value that represents seconds since the epoch.


Returns a string for this OID, with the OID given as 24 hex digits.

If the BSON_EXTJSON option is true, it will instead be compatible with MongoDB's extended JSON format, which represents it as a document as follows:

    {"$oid" : "012345678901234567890123"}


The string operator is overloaded so any string operations will actually use the 24-character hex value of the OID. Fallback overloading is enabled.

Both numeric comparison (<=>) and string comparison (cmp) are overloaded to do string comparison of the 24-character hex value of the OID. If used with a non-BSON::OID object, be sure to provide a 24-character hex string or the results are undefined.


This module is thread safe.


  • David Golden <david@mongodb.com>

  • Stefan G. <minimalist@lavabit.com>


This software is Copyright (c) 2018 by Stefan G. and MongoDB, Inc.

This is free software, licensed under:

  The Apache License, Version 2.0, January 2004