BSON object size of document retrieved from DB

Question

Mongo shell have the bsonsize() method to get BSON size of a given document retrieved from DB.

Is there any way of getting the same using PyMongo driver? I have found the bson module in the documentation but it is not fully clear to me how to use it to get the size of a document retrieved from DB.

Perhaps something like `len(bson.BSON.encode(document))`? – styvane Jul 20 '16 at 09:36 — styvane, Jul 20 '16 at 09:36

score 17 · Accepted Answer · answered Jul 20 '16 at 18:57

17

Based on @SSDMS suggestion (thanks!) the following can be used:

len(bson.BSON.encode(document))

I have tested with a couple of documents in my DB, comparing the result at mongo shell and with the above Python method and getting the same result:

At mongo shell:

> var doc1 = db.entities.findOne({'_id.id': '001'})
> var doc2 = db.entities.findOne({'_id.id': '002'})
> Object.bsonsize(doc1)
816
> Object.bsonsize(doc2)
819

At Python console:

>>> import bson
>>> from pymongo import MongoClient
>>> db = MongoClient('localhost', 27017)
>>> doc1 = db['orion']['entities'].find_one({'_id.id': '001'})
>>> doc2 = db['orion']['entities'].find_one({'_id.id': '002'})
>>> len(bson.BSON.encode(doc1))
816
>>> len(bson.BSON.encode(doc2))
819

answered Jul 20 '16 at 18:57

fgalan

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mongo have restriction of 16 MB for a document, may I know it this return number in python is in unit of MB or B? – Luk Aron Jan 10 '21 at 01:05
I think is in bytes – fgalan Jan 11 '21 at 21:21
1

Can confirm it's bytes – Mark Oct 31 '22 at 13:21

BSON object size of document retrieved from DB

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