https://nalar.dev/tags/postgresql/ Recent content in PostgreSQL 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> https://nalar.dev/postgresql-exclusion-constraints-non-overlapping-ranges/ Tue, 01 Sep 2026 00:00:00 +0700 https://nalar.dev/postgresql-exclusion-constraints-non-overlapping-ranges/ <p>Applications that schedule rooms, equipment, or maintenance windows often need a simple invariant: two active reservations for the same resource must not overlap. Checking for conflicts in application code looks easy, but concurrent transactions can both pass the check before either inserts.</p> <p>PostgreSQL can enforce this invariant inside the database with range types and exclusion constraints.</p> <h2 id="model-the-interval-explicitly">Model the interval explicitly</h2> <p>A half-open timestamp range includes its start and excludes its end. That lets adjacent bookings touch without overlapping.</p>