Hello,

The valid UTF8 character \u0000 is not handled properly : the string is cut at this character. Mongo is probably interpreting it as a string terminating character.
Example :

MongoDB shell version: 1.8.0
connecting to: test
> db.test.save(

{'text': 'foo\u0000bar'}

)
> db.test.findOne()

{ "_id" : ObjectId("4e3bbbaa4e496a38200a6f81"), "text" : "foo" }

> db.test.findOne(

{text: /foo/}

)

{ "_id" : ObjectId("4e3bbbaa4e496a38200a6f81"), "text" : "foo" }

> db.test.findOne(

{text: /bar/}

)
null

We use Mongo to log errors from various servers. We do not have any control on the string characters incoming and we have no workaround for this issue so far.
Thank you very much in advance for your feedback on this issue.

Cheers,
CH.