What is data dictionary, how to build and maintain it.

1. How to build a
Data Dictionary
Piotr Kononow
Founder @ Dataedo
https://dataedo.com

2. What is Data Dictionary
• A specification of tables (data sets) in a database
• List of columns/fields with their attributes
• Data Dictionary is (technical) metadata
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3. Sample Data Dictionary entry
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4. Elements of Data Dictionary
Relationships / Joins
List of data sets/tables
List of columns/fields
Data type
Constraints
Default values
Primary / unique keys
Allowed values
Data Dictionary
Ownership
Classification
Comments
SourcesStatus
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5. Why you should care about Data Dictionary?
• Find the data
• Understand the data
– Purpose of tables and columns
– Relationships/joins
– Sources
– Status/quality
• Capture knowledge about the data
• Share knowledge about the data
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6. Active vs Passive Data Dictionary
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7. Active Data Dictionary has many names
• „System Catalog Views” – MS SQL Server
• „System Catalog Tables” – Amazon Redshift, IBM Informix
• „System Catalogs” – PostgreSQL
• „System Views” – SAP HANA, Oracle
• „System Tables” – SAP/Sybase ASE, SAP HANA, Vertica, Firebird, …
• „Catalog Views” – IBM Db2
• „Information schema” – MySQL , Snowflake
• „Data Dictionary Views” – Oracle, Teradata
• …
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8. Active Data Dictionary views
• Sample MS SQL Server System Catalog Views:
– sys.tables
– sys.columns
– sys.view
– sys.foreign_keys
– sys.index_columns
– …
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9. Querying (Active) Data Dictionary
More at:
https://dataedo.com/kb/query/
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10. Data Dictionary in different platforms
• RDBMS/data warehouse: Integral part of a database, easily
accessible (active data dictionary)
• Document database/NoSQL (e.g. MongoDB) – embedded in
data itself, requires parsing
• Data Lake: external or none!
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11. Data Dictionary flow
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12. Where you can find Data Dictionary?
• Design documents / Spreadsheets
• DBMS – active data dictionary
• Data modeling tools
• Database documentation
• Data Dictionary tools / Metadata Reporisoties / Data Catalogs
• ETL tools
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13. Data Dictionary tools
• Spreadsheet or word processor
• DBMS active data dictionary + GUI tool
• Data Modeling tools (e.g. Erwin)
• Data Dictionary tools (e.g. Dataedo)
• Data Catalogs
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14. Building a
Data Dictionary

15. Data Dictionary with Dataedo
1. Metadata repository
2. Import metadata from data sources
3. Comments
4. Aliases
5. Additional metadata fields
6. Primary / unique keys
7. Relationships + diagrams
8. Organization with modules
9. Data Classification
10. Map Business Glossary
11. Share!
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16. Questions?
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17. Start today!
Free trial
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18. Thank you!
Piotr Kononow
Founder @ Dataedo
https://dataedo.com