Data Catalog vs. Data Dictionary: Definitions, Differences, Benefits & Why Do You Need Them?

July 4th, 2022


Data catalog vs. data dictionary: The difference

A data dictionary documents technical metadata for a specific database, whereas a data catalog acts as a unified context, control, and collaboration layer of all metadata (technical, governance, operational, collaboration, quality, and usage) across your entire data ecosystem.

To understand when you would end up needing a data catalog vs a data dictionary, read on. Here we cover:

  1. What is a data dictionary?
  2. What are the benefits of a data dictionary?
  3. What is a data catalog?
  4. 4 Fundamental features of a data catalog
  5. Data catalog vs. data dictionary vs. business glossary
  6. Data catalogs vs. data dictionaries in the real world
  7. Data dictionary vs. data catalog: Related reads

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What is a data dictionary?

A data dictionary provides information and insights about your database. Consider a data dictionary to be a documentation for databases.

A data dictionary provides insights on

  1. Data source (data warehouse, data lakes, databases, applications)
  2. Tables names and descriptions
  3. Table relationships
  4. Column name and descriptions
  5. Permissible values for a field
  6. Data types
  7. Column nullability
  8. Referential constraints — foreign keys and primary keys
  9. Column statistics — missing values, min-max values, and histogram distribution.
  10. Data and time when the property was created or changed
  11. Data owner
  12. Data freshness
  13. Classifications (PII, GDPR, HIPAA)

Example of how a data dictionary looks like

A data dictionary provides information about the database’s structure, data elements, constraints, and relationships. Image by Atlan

What are the benefits of a data dictionary?

The number of benefits your organization can have from a robust data dictionary is endless. Yet, let’s have a look at the top seven benefits of a data dictionary that acts as the interpreter for your databases:

  1. A data dictionary links physical data assets to business terms/concepts/metrics. This helps data users to understand and trust data better (improves data validity and credibility).
  2. Enables quick detection of anomalies and errors and hence helps keep a check on data quality.
  3. Checks how and where a field is referenced across the entire database.
  4. Provides a framework for programming and database standards to maintain data integrity.
  5. Helps evaluate data consistency during security and compliance audits.
  6. A data dictionary acts as self-serve documentation for new engineers/analysts. This greatly reduces onboarding time.
  7. Data dictionaries can be accessed externally through APIs for reporting and cataloging purposes.

And to learn more about each benefit in detail, check out the key benefits of a data dictionary.



What is a data catalog?

A data catalog is an inventory of data assets across all your data sources in your enterprise. It helps organizations discover, understand, and consume data better — all in one place.

A data catalog helps find answers to:
  • What data do we have?
  • Where does it come from?
  • Who is the owner?
  • How clean is the data & are there any gaps?
  • How is it classified?
  • Is the data good enough for running analysis?

4 fundamental features of a data catalog

Fundamentally, what does a data catalog do? A data catalog reduces the time to insight for data users. It ensures:

  1. Data is made readily accessible
  2. Context is provided
  3. The data lifecycle is visible
  4. Access permissions are defined

Watch a demo of Atlan data catalog


1. Data catalogs make data accessible

A data catalog automatically crawls, identifies, inventories, and classifies data assets from multiple sources. Data catalog tools allow you to run a search across data lakes, data warehouses, databases, tables, columns, SQL queries, and business glossaries.

Example of how a data catalog looks like

Modern data catalogs have google-like search interfaces that respond to text-based searches for data assets. Image by Atlan


2. Data catalogs provide context

People with no context of the data can learn more about it to decide if they have the right data.

Business glossary provides context to business terms and metrics

Modern data catalogs come with in-built business glossaries to ensure a common understanding of data assets and their usage across the organization. Image by Atlan


3. Data catalogs help visualize data lifecycle

Data catalogs enable you to visualize the complete lifecycle of a data asset, its transformation, and its dependency both upstream and downstream.

Data lineage helps visualize the data flow from source to dashboards

The best of modern data catalogs auto-construct the visual lineage of data to give an understanding of how data has evolved through its lifecycle and how changing the data will impact downstream. Image by Atlan


A Guide to Building a Business Case for a Data Catalog

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4. Data catalogs enable data governance

A data catalog helps enforce robust access control policies as guard rails to help you protect confidentiality and comply with various data protection regulations.

screenshot of Atlan data governance features

Modern data catalogs help deploy best-in-class data access governance without compromising on data democratization. Image by Atlan

Data catalog vs. data dictionary vs. business glossary

While evaluating the need for data catalogs and data dictionaries, people often stumble upon business glossaries. Here’s how the three are primarily different.

A data dictionary holds the technical metadata for a database, a business glossary pulls together a common understanding of business terms and concepts, whereas a data catalog is a unified access, control, and collaboration layer that spans all metadata across your data estate.

Think of it this way, a data dictionary helps understand and trust data in databases better, a business glossary provides a common language for the organization when it comes to business concepts and metrics, and a data catalog helps find, understand, trust and collaborate on data.

And to explore more about how a business glossary differs from the other two, check out business glossary vs. data catalog.

When does an organization need a data catalog?

It’s safe to say, deploying a data catalog is a right of passage for an organization to be truly data-driven. As a business, you can collect all the data that you want and set up best-in-class infrastructure to store that data, but data in itself is nothing. Just numbers.

You need the right data to reach the right person at the right time - for it to really move the needle on your business. Modern Data Catalogs are being designed to ensure that the complexities and scale of data do not deter “non-data” folks from using data in their day-to-day work.

→  Read in-depth about data catalogs.


Data catalogs vs. data dictionaries in the real world

As more and more data teams are feeling the need for and adopting data catalogs, the difference between a catalog and a dictionary is fast vanishing—and becoming more complementary—because catalog tools now crawl and inventory data dictionaries for metadata. Data dictionaries are now an integral part of a data catalog.

Just in case, if you are evaluating a data catalog, data dictionary, and metadata management for your team, do take Atlan for a spin.

Atlan is a modern data catalog built on the premise of embedded collaboration that is key in today’s modern workplace, borrowing principles from GitHub, Figma, Slack, Notion, Superhuman, and other modern tools that are commonplace today.


Ebook cover - metadata catalog primer

Everything you need to know about modern data catalogs

Adopting a modern data catalog is the first step towards data discovery. In this guide, we explore the evolution of the data management ecosystem, the challenges created by traditional data catalog solutions, and what an ideal, modern-day data catalog should look like. Download now!

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