Databricks and DWCC
Introduction
The steps to catalog the metadata from a data source using DWCC are as follows:
Read over the DWCC FAQ to familiarize yourself with the data.world DWCC collector.
Verify that your installation meets the prerequisites below.
Validate that you have a ddw-catalogs (or other) dataset set up to hold your catalog files when you are done running the collector.
Write the collector command and run it.
Upload the resulting file to your ddw-catalogs dataset (or other dataset as configured for your organization).
Prerequisites
The computer running the catalog collector should have connectivity to the internet or access to the source instance, a minimum of 2G memory, and a 2Ghz processor.
Docker must be installed. For more information see https://docs.docker.com/get-docker/.
The user defined to run DWCC must have read access to all resources being cataloged.
The computer running DWCC needs a Java Runtime Environment (JRE), version 11 or higher. (OpenJDK available here)
Permissions
The account used to authenticate needs to read the information schema of the databases about which it is collecting metadata. It does not need read access to the data within the tables.
What is cataloged
The information cataloged by the collector includes:
Writing the DWCC command
The easiest way to create your DWCC command is to:
Copy the example command below
Edit it for your organization and data source
Open a terminal window in any Unix environment that uses a Bash shell and paste your command into it.
The example command includes the minimal parameters required to run the collector (described below)--your instance may require more. A description of all the available parameters is at the end of this article. Edit the command by adding any other parameters you wish to use, and by replacing the values for all your parameters with your information as appropriate. Parameters required by the collector are in bold.
Important
Do not forget to replace x.y in datadotworld/dwcc:x.y with the version of DWCC you want to use (e.g., datadotworld/dwcc:2.80).
Basic parameters
These are the basic parameters needed to run the collector. A list of all parameter options is at the end of this article. Where available, either short (e.g., -a) or long (--account) forms can be used.
Docker and DWCC
Detailed information about the Docker portion of the command can be found here. When you run the command, run will attempt to find the image locally, and if it doesn't find it, it will go to Dockerhub and download it automatically:
Collector runtime and troubleshooting
The catalog collector may run in several seconds to many minutes depending on the size and complexity of the system being crawled. If the catalog collector runs without issues, you should see no output on the terminal, but a new file that matching *.dwec.ttl should be in the directory you specified for the output. If there was an issue connecting or running the catalog collector, there will be either a stack trace or a *.log file. Both of those can be sent to support to investigate if the errors are not clear. A list of common issues and problems encountered when running the collectors is available here.
Upload the .ttl file generated from running the collector
When the DWCC collector runs successfully, it creates a .ttl file in the directory you specified as the dwcc-output directory. The automatically-generated file name is databaseName.catalogName.dwec.ttl. You can rename the file or leave the default, and then upload it to your ddw-catalogs dataset (or wherever you store your catalogs.
Caution
If there is already a .ttl catalog file with the same name in your ddw-catalogs dataset, when you add the new one it will overwrite the existing one.
Automatic updates to your metadata catalog
Keep your metadata catalog up to date using cron, your Docker container, or your automation tool of choice to run the catalog collector on a regular basis. Considerations for how often to schedule include:
Frequency of changes to the schema
Business criticality of up-to-date data
For organizations with schemas that change often and where surfacing the latest data is business critical, daily may be appropriate. For those with schemas that do not change often and which are less critical, weekly or even monthly may make sense. Consult your data.world representative for more tailored recommendations on how best to optimize your catalog collector processes.