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Filesystem Pipelines Quickstart
This topic does not apply to MemSQL Helios.
Filesystem Pipeline Quickstart
To create and interact with a Filesystem Pipeline quickly, follow the instructions in this section.
To complete this Quickstart, your environment must meet the following prerequisites:
- Operating System: Mac OS X or Linux
- Docker: Version 1.12 or newer. If using Mac OS X, these instructions are written for Docker for Mac. Docker Toolbox is compatible as well, but no instructions are provided. While Docker is required for this Quickstart, Pipelines and MemSQL itself have no dependency on Docker.
Part 1: Creating a MemSQL Database and Filesystem Pipeline in Docker
Now that you have a directory that contains a file, you can use MemSQL to create a new pipeline and ingest the messages. In this part of the Quickstart, you will create a Docker container to run MemSQL and then create a new Filesystem pipeline.
In a new terminal window, execute the following command:
docker run --name memsql -p 3306:3306 -p 9000:9000 memsql/quickstart
This command automatically downloads the
memsql/quickstart Docker image from Docker Hub, creates a new container using the image, assigns the container a user-friendly name (
memsql), and finally starts the container.
You will see a number of lines outputted to the terminal as the container initializes and MemSQL starts. Once the initialization process is complete, open a new terminal window and execute the following command:
docker exec -it memsql /bin/bash
This opens up a command line in the docker container. The next set of commands will create the test_directory locally in the docker container and create a data file with the data to load into the database.
mkdir test_directory /* Create directory called 'test_directory' */ cd test_directory /* Navigate to new directory */ cat > books.txt /* Create a new file called 'books.txt' */ /* Copy the following text to the terminal: */ The Catcher in the Rye, J.D. Salinger, 1945 Pride and Prejudice, Jane Austen, 1813 Of Mice and Men, John Steinbeck, 1937 Frankenstein, Mary Shelley, 1818 Ctrl-D
For the purposes of this example, we have created the books.txt file in the test_directory in the root of the filesystem. In a typical real-world scenario, however, the filesystem extractor would be used with an NFS-mounted drive, with the source directory located on a different server.
For the next step you will create the database and table to receive the data.
memsql CREATE DATABASE books; USE books; CREATE TABLE classic_books ( title VARCHAR(255), author VARCHAR(255), date VARCHAR(255) );
These statements create a new database named
books and a new table named
classic_books, which has three columns:
Now that the destination database and table have been created, you can create a Filesystem pipeline. In Part 1 of this Quickstart, you uploaded the books.txt file to your bucket. To create the pipeline, you will need the following information:
- The name of the directory, such as:
CREATE PIPELINE library AS LOAD DATA FS '/absolute/path/to/test_directory' INTO TABLE `classic_books` FIELDS TERMINATED BY ',';
You can see what files the pipeline wants to load by running the following:
SELECT * FROM information_schema.PIPELINES_FILES;
If everything is properly configured, you should see one row in the
Unloaded state, corresponding to
CREATE PIPELINE statement creates a new pipeline named
library, but the pipeline has not yet been started, and no data has been loaded. A MemSQL pipeline can run either in the background or be triggered by a foreground query. Start it in the foreground first.
START PIPELINE library FOREGROUND;
When this command returns success, all files from your bucket will be loaded. If you check
information_schema.PIPELINES_FILES again, you should see all files in the
Loaded state. Now query the
classic_books table to make sure the data has actually loaded.
memsql> SELECT * FROM classic_books; +------------------------+-----------------+-------+ | title | author | date | +------------------------+-----------------+-------+ | The Catcher in the Rye | J.D. Salinger | 1945 | | Pride and Prejudice | Jane Austen | 1813 | | Of Mice and Men | John Steinbeck | 1937 | | Frankenstein | Mary Shelley | 1818 | +------------------------+-----------------+-------+
You can also have MemSQL run your pipeline in background. In such a configuration, MemSQL will periodically poll the directory for new files and continuously them as they are added to the bucket. Before running your pipeline in the background, you must reset the state of the pipeline and the table.
DELETE FROM classic_books; ALTER PIPELINE library SET OFFSETS EARLIEST;
The first command deletes all rows from the target table. The second causes the pipeline to start from the beginning, in this case, “forgetting” it already loaded
books.txt so you can load it again. You can also drop and recreate the pipeline, if you prefer.
To start a pipeline in the background, run
START PIPELINE library;
This statement starts the pipeline. To see whether the pipeline is running, run
SHOW PIPELINES; +----------------------+---------+ | Pipelines_in_books | State | +----------------------+---------+ | library | Running | +----------------------+---------+
At this point, the pipeline is running and the contents of the books.txt file should once again be present in the
Foreground pipelines and background pipelines have different intended uses and behave differently. For more information, see the START PIPELINE topic.
Now that you have a running pipeline, any new files you add to your bucket will be automatically ingested. To understand how a Filesystem pipeline ingests large amounts of files in a directory, see the Parallelized Data Loading section in the Extractors topic. You can also learn more about how to transform the ingested data by reading the Transforms topic.