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EXPLAIN ANALYZE is not only a DBA tool. For backend engineers, it is a practical way to understand why a PostgreSQL query is slow, whether the problem is a sequential scan, a nested loop, a sort, or simply reading too many buffers.
Multi-tenant PostgreSQL design is not only about where to put `tenant_id`. The real decision is how much isolation, operability, performance predictability, and restore precision your SaaS product needs as customers and data volume grow.
N+1 queries are not just an ORM inconvenience. In production, they turn simple page loads into repeated database round trips, inflate PostgreSQL latency, hide inside clean application code, and become expensive exactly when traffic grows.
PostgreSQL indexes are not a checklist item. The useful ones match real predicates, joins, uniqueness rules, and ordering needs. The harmful ones duplicate existing access paths, index low-value columns, or optimize rare reads while making every write more expensive.
Connection pools protect latency only when they are sized against the database, not against application traffic. In Go services, `database/sql`, `pgx`, PgBouncer, timeouts, transactions, and deadlocks must be treated as one production system.
When a PostgreSQL-backed application “freezes”, the database server is often healthy. The real problem is usually concurrency: long transactions, row locks, migration locks, or deadlocks turning normal requests into lock wait chains.