Exporting data

Limitations

Exporting isn’t supported for the interval field type.

Exporting with default settings

The command below exports data of the customers space to the customers.csv file:

$ tt crud export localhost:3301 customers:customers.csv

If the customers space has five fields (id, bucket_id, firstname, lastname, and age), the file with exported data might look like this:

1,477,Andrew,Fuller,38
2,401,Michael,Suyama,46
3,2804,Robert,King,33
# ...

If a tuple contains a null value, for example, [1, 477, 'Andrew', null, 38], it is exported as an empty value:

1,477,Andrew,,38

Exporting headers

To export data with a space’s field names in the first row, use the --header option:

$ tt crud export localhost:3301 customers:customers.csv  \
                 --header

In this case, field values start from the second row, for example:

id,bucket_id,firstname,lastname,age
1,477,Andrew,Fuller,38
2,401,Michael,Suyama,46
3,2804,Robert,King,33
# ...

Exporting compound data

By default, tt exports empty values for fields containing compound data such as arrays or maps. To export compound values in a specific format, use the --compound-value-format option. For example, the command below exports compound values serialized in JSON:

$ tt crud export localhost:3301 customers:customers.csv  \
                 --compound-value-format json

Options

--batch-queue-size INT¶

The maximum number of tuple batches in a queue between a fetch and write threads (the default is 32).

tt exports data using two threads:

• A fetch thread makes requests and receives data from a Tarantool instance.
• A write thread encodes received data and writes it to the output.

The fetch thread uses a queue to pass received tuple batches to the write thread. If a queue is full, the fetch thread waits until the write thread takes a batch from the queue.

--batch-size INT¶

The number of tuples to transfer per request (the default is 10000).

--compound-value-format STRING¶

A format used to export compound values like arrays or maps. By default, tt exports empty values for fields containing such values.

Supported formats: json.

See also: Exporting compound data.

--header¶

Add field names in the first row.

See also: Exporting headers.

--password STRING¶

A password used to connect to the instance.

--readview¶

Export data using a read view.

--username STRING¶

A username for connecting to the instance.