{"head":{"title":"What Is a Data Warehouse? Definition and Example | OceanLab","description":"A data warehouse is a database built for analysis, holding cleaned data from many systems in one place. How it differs from an app database, plus mistakes.","canonical":"https://oceanlab.in/glossary/data-warehouse"},"crumbs":[{"name":"Home","path":"/"},{"name":"Glossary","path":"/glossary"},{"name":"data warehouse","path":"/glossary/data-warehouse"}],"slug":"data-warehouse","term":"Data warehouse","aka":[],"category":"System design","short":"A database built for analysis and reporting, where cleaned data from many systems is kept together in one place.","body":[["Your app's database is built for many small reads and writes. A warehouse is built for large queries over lots of rows, such as revenue by month by region. Data from the app, payments, CRM and marketing tools is copied in, usually by an ",{"href":"/glossary/etl","text":"ETL"}," or ELT pipeline, and shaped into tables that are easy to query."],["Warehouses usually store data by column, which makes big scans and totals fast. Analysts and BI tools query the warehouse, not the live app."]],"why":["Running heavy reports on the production database slows the app down for users. A warehouse separates the two and gives one trusted place for numbers, so finance, product and sales stop arguing over whose spreadsheet is right."],"example":["A subscription business wants churn by acquisition channel. Signups live in the app database, payments with the payment provider and channels in the marketing tool. A nightly pipeline loads all three into the warehouse, and one query answers the question."],"inBuild":["We send product events and database changes to the warehouse through a pipeline, define key metrics once in shared models, and leave personal data out or masked where the analysis does not need it. Access to the warehouse follows the same ",{"href":"/glossary/rbac","text":"role rules"}," as the app."],"mistakes":[["Copying raw data in with no shared definitions, so every report counts differently."],["Putting personal data in the warehouse with weaker access controls than the app."],["Using the warehouse to power user-facing features that need fast, fresh reads."]],"related":[{"href":"/glossary/etl","label":"ETL (extract, transform, load)","detail":"A data pipeline that pulls data out of source systems, cleans and reshapes it, and loads it into a destination such as a data warehouse."},{"href":"/glossary/read-replica","label":"Read replica","detail":"A read-only copy of a database that is kept in sync with the main database and takes read queries off it."},{"href":"/glossary/event-driven-architecture","label":"Event-driven architecture","detail":"A way of designing software where parts of the system publish events about what happened, and other parts react to them on their own."},{"href":"/glossary/ab-test","label":"A/B test","detail":"An experiment that shows two versions of something to random groups of users and measures which one does better on a chosen metric."},{"href":"/glossary/object-storage","label":"Object storage","detail":"A way of storing files as objects in buckets, each with an ID and metadata, reached over HTTP and built to scale to huge amounts of data cheaply."}],"tools":[{"href":"/tools/internal-tool-roi","label":"Internal tool ROI","detail":"Free tool"}],"links":[{"href":"/pricing/categories/databases","label":"Database pricing","detail":"Managed database prices, with sources."}],"sources":[],"legal":false,"updatedAt":"2026-10-25"}