Using WASB

This section describes how you interact through the Designer Cloud Powered by Trifacta® platform with your WASB environment.

• WASB is a scalable file storage system for use across all of the nodes (servers) of an HDInsight cluster. As with HDFS for Hadoop, many interactions with WASB are similar with desktop interactions with files and folders. However, what looks like a "file" or "folder" in WASB may be spread across multiple nodes in the cluster. For more information on HDInsight, see https://azure.microsoft.com/en-us/services/hdinsight/.

Uses of WASB

The Designer Cloud Powered by Trifacta platform can use WASB for the following tasks for reading and writing data:

1. Importing datasets from WASB Files: You can read in from source data stored in WASB. An imported dataset may be a single WASB file or a folder of identically structured files. See Reading from Sources in WASB below.
2. Reading Datasets: When creating a dataset, you can pull your data from a source in WASB. See Creating Datasets below.
3. Writing Results: You can publish your results directly to WASB. See Writing Job Results below.
4. Publishing Job Results: After a job has been executed, you can write the results back to WASB. See Writing Job Results below.

In the Designer Cloud application, WASB is accessed through the WASB browser. See WASB Browser.

Before You Begin Using WASB

• Read/Write Access: Your HDInsight administrator must configure read/write permissions to locations in WASB. Please see the WASB documentation provided with your HDInsight distribution.

  Avoid using /trifacta/uploads for reading and writing data. This directory is used by the Designer Cloud application.

  NOTE: If a directory is created on the HDI cluster through WASB, the directory includes a Size=0 blob. The Designer Cloud Powered by Trifacta platform does not list them and does not support interaction with Size=0 blobs.

• Your HDInsight administrator should provide a place or mechanism for raw data to be uploaded to your HDInsight datastore.

• Your HDInsight administrator should provide a writeable home output directory for you. This directory location is available through your user profile. See User Profile Page.

Secure Access

Client-side encryption is not supported. Through WASBS, HTTPS is supported.

Storing Data in WASB

Your HDInsight administrator should provide raw data or locations and access for storing raw data within WASB. All Alteryx users should have a clear understanding of the folder structure within WASB where each individual can read from and write their job results. 

• Users should know where shared data is located and where personal data can be saved without interfering with or confusing other users.
• The Designer Cloud application stores the results of each job in a separate folder in WASB.

Reading from Sources in WASB

You can import a dataset from one or more files stored in WASB. When you select a folder in WASB for your imported dataset, you select all files in the folder to be included. Notes:

• This option selects all files in all sub-folders. If your sub-folders contain separate datasets, you should be more specific in your folder selection.
• All files used in a single imported dataset must be of the same format and have the same structure. For example, you cannot mix and match CSV and JSON files if you are reading from a single directory. Files of the same format must have identical column structures.
• When a folder is selected from WASB, the following file types are ignored:
  
  • *_SUCCESS and *_FAILED files, which may be present if the folder has been populated by Hadoop.
  • If you have stored files in WASB that begin with an underscore (_), these files cannot be read during batch transformation and are ignored. Please rename these files through WASB so that they do not begin with an underscore.

Creating Datasets

When creating a dataset, you can choose to read data in source data stored from WASB or from a local file.

• WASB sources are not moved or changed.
• Local file sources are uploaded to /trifacta/uploads where they remain and are not changed.

Data may be individual files or all of the files in a folder.

• For more information, see Reading from Sources in WASB.
• In the Import Data page, click the WASB tab. See Import Data Page.

Writing Job Results

When your job results are generated, they can be stored back in WASB at the location defined for your user account.

• As part of the job specification, you can create a publishing target in WASB. See Run Job Page.
• For ad-hoc publication to WASB, the target location is available through the Export Results window for the job in the Jobs page. See Export Results Window.
• Each set of job results must be stored in a separate folder within your WASB output home directory. 
• For more information on your output home directory, see User Profile Page.

Creating a new dataset from results

As part of writing job results, you can choose to create a new dataset, so that you can chain together data wrangling tasks.