@0xlelouch_: 90% of PostgreSQL in 2026 comes down to mastering these 10 concepts: 1) MVCC + vacuum. Old row versions stick around; a…

90% of PostgreSQL in 2026 comes down to mastering these 10 concepts: 1) MVCC + vacuum. Old row versions stick around; autovacuum settings decide if you get bloat or stable latency. 2) Indexes beyond B-tree. Know when to use partial, covering (INCLUDE), GIN for jsonb/text search, and why unused indexes still hurt writes. 3) Query plans. EXPLAIN (ANALYZE, BUFFERS) is the fastest path from guesswork to facts: rows, loops, actual time, cache vs disk. 4) Locks + isolation. Most outages are lock queues, not slow queries; learn lock modes, deadlocks, and why long transactions block vacuum. 5) Connection management. Too many clients kills you; use pgbouncer, size pools, and watch idle-in-transaction like a hawk. 6) WAL + checkpoints. Spiky write latency often comes from checkpoint pressure; tune checkpoint_timeout, max_wal_size, and disk throughput. 7) Replication + failover tradeoffs. Streaming replication is easy until you need RPO/RTO numbers, read-after-write consistency, and promotion safety. 8) Migrations in prod. Adding a column is cheap; backfilling isn’t. Prefer expand/contract, avoid ACCESS EXCLUSIVE locks, and batch updates. 9) Observability that matters. Track p95 query time, dead tuples, autovacuum runs, replication lag, cache hit ratio, and top wait events. 10) Security basics people skip. Least-priv roles, RLS for multi-tenant, rotate creds, lock down extensions, and never run the app as a superuser