Suggest an editImprove this articleRefine the answer for “What is data redundancy?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)Data redundancy is a situation where the same information is stored in a database in several places at once, usually because data is repeated across different tables unnecessarily, or because the database wasn't normalized. **Key point:** redundancy causes update errors (data changes in one place but not the others), wastes storage space, and makes maintenance harder - which is why normalization is considered the primary way to eliminate it.Shown above the full answer for quick recall.Answer (EN)Image**Data redundancy** is a situation where **the same information is stored in a database in several places at once**. ### The main points 1. **Causes of redundancy** - Repeating data across different tables unnecessarily. - The database not being normalized. 2. **Problems redundancy causes** - **Update errors**: if data changes in one place but not the others, an inconsistency shows up. - **Wasted storage**: duplicate records take up extra space. - **Harder maintenance**: it's harder to manage, search, and analyze the information. 3. **Example** - The `Employees` table has a `DepartmentName` field, and a separate `Departments` table also stores `DepartmentName`. - If a department's name changes, it has to be changed in two places, which risks errors. Put simply, **redundancy is unnecessary repetition of data**, which creates problems with consistency and how efficiently the database works.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.