Mongoimport has flaws in how it handles TSV files, particularly regarding the types of data that are imported.

A simple example to demonstrate:

1) Start with the following sample file represented the exported document

{ a : true }

$cat test.tsv
a
true

2) Import this file
$mongoimport -d test -c test -f a --type tsv --file test.tsv --headerline

3) Look at the document
$mongo
>db.test.find()

{ "_id" : ObjectId("5147741f12da7a6b27ff5c58"), "a" : "true" }

This document has the value "true" the string, rather than true the boolean.

A issues exists for importing subdocuments where what is imported is a string representation of the subdocument rather than an actual subdocument.

Beyond this, if a string is stored like "string" (where the value is what is inside the quotes), the imported value will be "\"string\"".