https://nalar.dev/tags/indexes/ Recent content in Indexes on Nalar Hugo en-us Wed, 02 Sep 2026 00:00:00 +0700 https://nalar.dev/covering-indexes-and-index-only-scans/ Wed, 02 Sep 2026 00:00:00 +0700 https://nalar.dev/covering-indexes-and-index-only-scans/ <p>An index normally helps a database find rows. A covering index can go further: it contains all columns needed by a query, allowing the database engine to answer some reads without fetching every matching row from the table.</p> <p>That can reduce random I/O for read-heavy workloads, but it also makes indexes larger and writes more expensive. Covering is a workload-specific optimization, not a reason to copy every selected column into every index.</p>