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Partitions
DSE Version: 6.0
Video
Exercises
Exercise 3 – Partitions
In this exercise, you will:
- Experiment with partitions
Steps
NOTE: Be sure Apache Cassandra™ is running before doing these exercises. You can check by running dsetool on the command line:/home/ubuntu/node/bin/dsetool
status
1) Start the CQL command shell at the command line:/home/ubuntu/node/resources/cassandra/bin/cqlsh
2) Switch to the killrvideo keyspace via the USE
command:USE killrvideo;
3) Execute the following command to view the metadata for the videos table you created earlier.DESCRIBE TABLE videos;
- What is the partition key?
- How many partitions are in this table?
4) Execute the following query to view the partitioner token value for each video id.SELECT token(video_id), video_id
FROM videos;
5) Exit cqlsh and use the following command to inspect the file named /home/ubuntu/labwork/data-files/videos-by-tag.csv:cat /home/ubuntu/labwork/data-files/videos-by-tag.csv
6) Restart cqlsh and switch to the killrvideo keyspace.
7) Your mission, should you choose to accept it, is to write a CREATE TABLE
statement that will store this data partitioned by tags. With this given data set, there should be two partitions, one for each tag. Call your table videos_by_tag.
8) Execute the following COPY
command to import the videos-by-tag.csv data.COPY videos_by_tag(tag, video_id, added_date, title) FROM '/home/ubuntu/labwork/data-files/videos-by-tag.csv' WITH HEADER = TRUE;
9) Verify CQL imported your data correctly by writing a SELECT *
command.SELECT * FROM videos_by_tag;
- Note that if the table only contains 2 records, the primary key may be wrong -containing only the tag field -be sure to include the video_id as a cluster column.
10) Write a SELECT
statement to retrieve all rows tagged with cassandra.
11) Now, find all videos tagged with datastax (similar to the previous query).
12) Finally, write a query to retrieve the video having a title of Cassandra Intro.