advancedDatabase Optimization Techniques
What is a covering index and how does it eliminate table lookups entirely for a query?
Tests whether you know an index that already contains every selected column skips the extra trip to the actual table row.
Ready to master this question?
Generate a complete walkthrough — background, the full answer in plain language, a working code example explained line by line, a real-world scenario, common mistakes, and how this same question gets asked in different ways.
Sign in to generate a response