Database Reference
In-Depth Information
The following options deserve more explanation:
•
--headerline
: Uses the first line of the file as the list of field names. Note that this applies only
to CSV and TSV formats.
•
--ignoreblanks
: Does
not
import empty fields. If a field is empty, then a corresponding
element will not be created in the document for that row; if you don't invoke this option, then
an empty element with the column name is created.
•
--drop
: Drops a collection and then re-creates it with data only from this import; otherwise,
the data is appended to the collection.
You also have to specify the database name and the collection name when you use
mongoimport
to import data
with the
-d
and
-c
options, as in the following example:
$mongoimport -d blog -c tagcloud --type csv --headerline < csvimportfile.csv
Exporting Data from MongoDB
The
mongoexport
utility is similar to
mongoimport
, but
mongoexport
, as its name implies, creates export files from
an existing MongoDB collection instead. This is one of the best ways to extract data from your MongoDB instance
in a format that can be read by other databases or spreadsheet applications. Figure
9-4
shows how to use the
mongoexport
utility.
