What is Lineage in ETL? Use Cases, Roles, and Tool Considerations

Updated May 25th, 2023
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Data lineage in ETL (Extract, Transform, Load) refers to the life cycle of data, from its origins to where it moves over time.

It provides visibility into the analytics pipeline and simplifies tracing errors back to their sources. It also enables analysts to see how changes in the underlying data could impact reports and other analytic outputs.

Essentially, it provides a method of tracking data from its source to its final destination, which can include the transformations it undergoes during its journey.

Let’s take a look at the different transformations that data undergoes.

Table of contents #

  1. Exploring data transformations in ETL processes
  2. Common use cases of data lineage in ETL
  3. Data lineage in ETL: identifying the primary user and other relevant roles
  4. Evaluating data lineage tools: what to look for
  5. Summary
  6. What is lineage in ETL? Related reads

Exploring data transformations in ETL processes #

Data lineage is especially important in ETL processes because of the complexity of data transformations.

This can include simple transformations like:

  • Data cleaning
  • Normalization

It can include more complex operations like:

  • Joining data from different sources,
  • Filtering
  • Aggregating
  • Summarizing

In practical terms, data lineage can answer questions like:

  • Where did this data come from? (Origin)
  • Where is this data being used? (Destination)
  • What happens to the data as it travels from source to destination? (Transformations)
  • Who is responsible for the data at various stages in its lifecycle? (Ownership)

Having a complete data lineage is critical to ensuring data quality, reliability, and trustworthiness. It supports regulatory compliance (e.g., GDPR, CCPA), aids in debugging and error tracing, helps with data governance, and enables impact analysis and change management.

A data lineage tool can help automate the collection and visualization of data lineage information.

It can be as simple as a series of diagrams showing the flow of data, or as complex as a comprehensive metadata management system that includes data cataloging, data dictionary, and data governance functionalities.

Common use cases of data lineage in ETL #

In this section we’ll explore some revised use cases for data lineage in ETL with specific examples:

  1. Debugging data quality issues
  2. Impact analysis for system changes
  3. Regulatory compliance and auditing
  4. Data migration
  5. Data privacy and security
  6. Reproducibility in analytics and machine learning

Let’s take a closer look at these use cases:

1. Debugging data quality issues #

  • Suppose a data analyst notices an anomaly in a weekly sales report. With the help of data lineage, they can trace back through each transformation stage of the ETL process to identify where the issue originated.
  • This might reveal that a new discount code was incorrectly coded in the extract stage, leading to miscalculated sales figures.

2. Impact analysis for system changes #

  • If your organization is planning to upgrade the database software or wants to make a change in the ETL process, it is crucial to understand how these changes might impact downstream data and reports.
  • With data lineage, you can see exactly which reports and dashboards are sourced from the systems about to change, helping you assess the risk and prepare accordingly.

3. Regulatory compliance and auditing #

  • Let’s say you’re in a heavily regulated industry like finance, and an auditor wants proof that your loan approval process isn’t discriminatory.
  • Your data lineage can show the auditor the entire journey of your data – from initial customer application, through various transformations and filters, all the way to the final approval decision.

4. Data migration #

  • Consider a situation where your company is moving data from an on-premises data warehouse to a cloud-based one.
  • Data lineage can provide a map of how data is transformed and loaded, ensuring a consistent and accurate migration.
  • For instance, you might find that certain ETL transformations on the on-premises system are no longer required or need to be modified in the cloud environment.

5. Data privacy and security #

  • Imagine you’re working with healthcare data, where patient privacy is paramount.
  • With data lineage, you can ensure that all transformations are HIPAA-compliant, showing that personally identifiable information (PII) is correctly anonymized or encrypted before it is loaded into the data warehouse for analysis.

6. Reproducibility in analytics and machine learning #

  • Suppose a data scientist develops a predictive model for customer churn that becomes an integral part of your business strategy. Over time, the performance of the model starts to degrade.
  • With data lineage, you can trace back to see how the training data for the model was generated. This enables you to investigate whether changes in the ETL process could be affecting model performance.

In each of these cases, the power of data lineage in ETL lies in the visibility it provides, allowing for effective troubleshooting, risk management, and trust in the integrity of your data.

Data lineage in ETL: Identifying the primary user and other relevant roles #

The primary individual who typically needs access to data lineage in ETL is the data engineer. They are usually responsible for the design, construction, and maintenance of the ETL process, making them the primary custodian of data lineage.

They need data lineage information to debug issues, assess the impact of changes, and ensure data consistency and quality.

However, there are several other roles that might also need access to data lineage in ETL:

  1. Data analysts and business intelligence analysts
  2. Data scientists
  3. Data stewards or data governance professionals
  4. Database administrators (DBAs)
  5. IT auditors and compliance officers
  6. Project managers or product owners

Let’s look into these roles in detail:

1. Data analysts and business intelligence analysts #

  • These individuals often need to trace back the origins of the data they are using to ensure its validity.
  • Data lineage helps them understand where the data comes from, how it’s transformed, and whether they can trust it for their reporting and analytical tasks.

2. Data scientists #

  • They need data lineage to understand how the data they are using in their models was prepared and transformed.
  • This is important for model reproducibility, model debugging, and understanding how changes in data might affect their models.

3. Data stewards or data governance professionals #

  • They are typically responsible for data quality, data privacy, and compliance with regulations.
  • Data lineage is crucial for them to ensure that data policies and standards are being adhered to throughout the data lifecycle.

4. Database administrators (DBAs) #

  • They might need access to data lineage when they’re involved in data migration projects, system upgrades, or when troubleshooting performance issues related to data loading.

5. IT auditors and compliance officers #

  • They might require data lineage to confirm regulatory compliance and for auditing purposes.
  • It provides them with a transparent view of data transformations, helping them ensure that data processing meets internal and external standards.

6. Project managers or product owners #

  • These individuals might need to understand data lineage in the context of planning new features, managing dependencies, and assessing the potential impact of changes in the data landscape.

In essence, while the data engineer is the primary role that deals with data lineage, access to and understanding of data lineage can be valuable across various roles in a data-driven organization.

Evaluating data lineage tools: What should you look for? #

Evaluating a data lineage tool involves a thorough assessment of its capabilities to meet the needs of your various team members while keeping an eye on the present and future scalability of your data ecosystem.

Below are a few important criteria to consider:

  1. Coverage and support
  2. Automation
  3. Depth and granularity
  4. Integration
  5. Metadata contextualization
  6. Actionability
  7. Scalability and performance
  8. Usability and accessibility

Let’s take a deep dive into these criteria:

1. Coverage and support #

  • The tool should be able to cover all the data sources, transformations, and destinations your business uses. Consider both current and future data sources when evaluating a tool.
  • The tool’s support for different types of SQL statements is important.
  • The more types it supports, the more comprehensive the data lineage will be.

2. Automation #

  • Automatic parsing of SQL queries and the ability to programmatically create and retrieve lineage data is crucial. Automation minimizes manual work and can make the tool more efficient and scalable.

3. Depth and granularity #

  • The tool should offer lineage at both table and column level.
  • Column-level lineage gives a deeper insight into the transformations and is crucial for tasks like root cause analysis, impact analysis, and data governance.

4. Integration #

  • The tool should natively integrate with both upstream and downstream tools used in your data workflow.
  • This includes integration with data integration tools, business intelligence tools, and data processing tools like Spark or Databricks.

5. Metadata contextualization #

  • The tool should incorporate other types of metadata to provide additional context for assets in the lineage graph.
  • Operational, quality, business/semantic, owner, and social metadata can all provide valuable insights that aid in understanding and troubleshooting data lineage.

6. Actionability #

  • A good data lineage tool doesn’t just provide insights; it also enables action.
  • This could be in the form of triggering automated workflows, sending alerts, or allowing changes to be made directly from the lineage graph.

7. Scalability and performance #

  • As your data ecosystem grows, your data lineage tool needs to keep up. It’s important to choose a tool that is designed for the cloud, scalable and can handle large-scale SQL parsing demands.

8. Usability and accessibility #

  • Lastly, the tool should be user-friendly and accessible to different team members, not just data engineers.
  • It should provide different views or modes to cater to different roles, from data scientists to compliance officers.

Remember that the right tool will largely depend on your specific use cases, the size and complexity of your data ecosystem, and your team’s skillset. Make sure to try out the tool with your data, ideally in a pilot project, before making a final decision.

Summary #

In conclusion, data lineage is a critical component of the ETL process. It helps organizations understand the origins, transformations, and movements of data. This information about data can be used to ensure data quality, comply with regulations, make informed decisions, and improve data literacy.

By understanding the key use cases and considerations for selecting a data lineage tool, organizations can harness the power of data lineage to optimize their ETL processes and leverage data effectively for their business needs.

Want to learn more? Check out some of the top open-source lineage tools, and learn how you can set up lineage for your organization.

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