Mike Friedman > MongoDB-0.46.3 > MongoDB::BSON::Binary



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Module Version: 0.46.3   Source   Latest Release: MongoDB-v1.4.2


MongoDB::BSON::Binary - A type that can be used to send binary data to the database


Creates an instance of binary data with a specific subtype.


For example, suppose we wanted to store a profile pic.

    my $pic = MongoDB::BSON::Binary->new(data => $pic_bytes);
    $collection->insert({name => "profile pic", pic => $pic});

You can also, optionally, specify a subtype:

    my $pic = MongoDB::BSON::Binary->new(data => $pic_bytes,
        subtype => MongoDB::BSON::Binary->SUBTYPE_GENERIC);
    $collection->insert({name => "profile pic", pic => $pic});


MongoDB allows you to specify the "flavor" of binary data that you are storing by providing a subtype. The subtypes are purely cosmetic: the database treats them all the same.

There are several subtypes defined in the BSON spec:

SUBTYPE_GENERIC (0x00) is the default used by the driver (as of 0.46).
SUBTYPE_FUNCTION (0x01) is for compiled byte code.
SUBTYPE_GENERIC_DEPRECATED (0x02) is deprecated. It was used by the driver prior to version 0.46, but this subtype wastes 4 bytes of space so SUBTYPE_GENERIC is preferred. This is the only type that is parsed differently based on type.
SUBTYPE_UUID_DEPRECATED (0x03) is deprecated. It is for UUIDs.
SUBTYPE_UUID (0x04) is for UUIDs.
SUBTYPE_MD5 can be (0x05) is for MD5 hashes.
SUBTYPE_USER_DEFINED (0x80) is for user-defined binary types.


A string of binary data.


A subtype. Defaults to SUBTYPE_GENERIC.


Binary data is stored with the length of the binary data, the subtype, and the actually data. SUBTYPE_GENERIC DEPRECATED stores the length of the data a second time, which just wastes four bytes.

If you have been using SUBTYPE_GENERIC_DEPRECATED for binary data, moving to SUBTYPE_GENERIC should be painless: just use the driver normally and all new/resaved data will be stored as SUBTYPE_GENERIC.

It gets a little trickier if you've been querying by binary data fields: SUBTYPE_GENERIC won't match SUBTYPE_GENERIC_DEPRECATED, even if the data itself is the same.


Other languages were using the UUID type to deserialize into their languages' native UUID type. They were doing this in different ways, so to standardize, they decided on a deserialization format for everyone to use and changed the subtype for UUID to the universal format.

This should not affect Perl users at all, as Perl does not deserialize it into any native UUID type.

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