Key vs Non-Key Column Database Indexing

Hussein Nasser breaks down the nuts and bolts of indexing in relational databases, explaining how key columns (the ones you build your index on) differ from non-key (included) columns that you can tack onto an index for extra data coverage. He keeps it informal but practical, so you’ll grasp why some columns live in the index’s core and others just ride along.

By adding non-key columns as “included” fields, you can often skip expensive table lookups and answer queries straight from the index—making your reads much faster without bloating your primary keys. A quick, hands-on tipfest that’ll have you squeezing more performance out of every index.

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