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Bulk export

YCQL

This page documents bulk export for YugabyteDB’s Cassandra-compatible YCQL API. To export data from a YugabyteDB (or an Apache Cassandra) table, you can use the cassandra-unloader tool.

We will first create a source YugabyteDB table and populate it with data. Then you will export the data out using the cassandra-unloader tool. We will use a generic gaming user profile use case as a running example to illustrate the export process.

Create Source Table

Following is the schema of the destination YugabyteDB table.

CREATE KEYSPACE load;
USE load;

CREATE TABLE users(
	user_id varchar,
	score1 double,
	score2 double,
	points int,
	object_id varchar,
   PRIMARY KEY (user_id));

Generate Sample Data

# sample usage:
#  To generate a 10GB (10240 MB) file.
#  % python gen_csv.py <outfile_name> <outfile_size_MB>
#  % python gen_csv.py file01.csv 10240
#
import numpy as np
import uuid
import csv
import os
import sys
outfile    = sys.argv[1] # output file name
outsize_mb = int(sys.argv[2])
print("Outfile = " + outfile)
print("Outfile Size (MB) = " + str(outsize_mb))
chunksize = 10000
with open(outfile, 'ab') as csvfile:
    while (os.path.getsize(outfile)//1024**2) < outsize_mb:
        data = [[uuid.uuid4() for i in range(chunksize)],
                np.random.random(chunksize)*1000,
                np.random.random(chunksize)*50,
                np.random.randint(1000000, size=(chunksize,)),
                [uuid.uuid4() for i in range(chunksize)]]
        csvfile.writelines(['%s,%.6f,%.6f,%i,%s\n' % row for row in zip(*data)])

Sample rows generated by script would like the following.

$ head file00.csv

3399bebc-d2cc-40c6-89d4-26102e08ff61,622.491927,40.262305,658257,44d73f8c-1d3c-424e-8fd2-d316c56b8454
4f362eac-f79f-45f6-b6b1-bd5a81f931dc,141.344278,3.024717,694290,7768b010-8411-490a-b523-88cc3ec53cb5
a24a6587-eea4-4907-ac7f-9f99dcac8f82,345.110599,3.869150,510943,5765d1d3-2855-4dbe-9f11-bb3b8631789f
...

To generate 5 CSV files of about 5 GB each, run the following commands.

python ./gen_csv.py file00.csv 5120 &
python ./gen_csv.py file01.csv 5120 &
python ./gen_csv.py file02.csv 5120 &
python ./gen_csv.py file03.csv 5120 &
python ./gen_csv.py file04.csv 5120 &

Load Sample Data

cassandra-loader is a general purpose bulk loader for CQL that supports various types of delimited files (particularly CSV files). For more details, review the README of the YugabyteDB cassandra-loader fork. Note that cassandra-loader requires quotes for collection types (for example, “[1,2,3]” rather than [1,2,3] for lists).

Install cassandra-loader

You can do this as shown below.

$ wget https://github.com/yugabyte/cassandra-loader/releases/download/v0.0.27-yb-2/cassandra-loader

$ chmod a+x cassandra-loader

Run cassandra-loader

The files can be queued up for upload one at a time. Sample invocation:

./cassandra-loader \
    -schema "load.users(user_id, score1, score2, points, object_id)" \
    -boolStyle 1_0 \
    -numFutures 1000 \
    -rate 10000 \
    -queryTimeout 65 \
    -numRetries 10 \
    -progressRate 200000 \
    -host <clusterNodeIP> \
    -f file01.csv

For additional options to cassandra-loader, see here.

Export Data

Install cassandra-unloader

$ wget https://github.com/brianmhess/cassandra-loader/releases/download/v0.0.27/cassandra-unloader

$ chmod a+x cassandra-unloader

Run cassandra-unloader

./cassandra-unloader \
   -schema "load.users(user_id, score1, score2, points, object_id)" \
   -boolStyle 1_0 \
   -host <clusterNodeIP> \
   -f outfile.csv

For additional options to cassandra-unloader, see here.

Always specify timezone

The time zone is not added to the default timestamp formats when using the cassandra-loader and cassandra-unloader utilities. Make sure that timestamps are exported and imported in the same format, including the time zone. Examples: yyyy-MM-dd HH:mm:ss.SSSZ and yyyy-MM-dd HH:mm:ss.SSSXXX.

Use tab character for delim on JSONB columns

The default delimiter (,) does not work with JSONB columns. Use the tab character for delim -delim $'\t'.