#databases

Engineering at Scale

Engineering at Scale 11 min read

What is connection pooling, and how does it work?

Why opening database connections is expensive, how pools lend and reuse them, two-tier pooling on large systems, Django's pool options, and the settings that matter.

PS Prajjwal Sinha Sep 24, 2026

Engineering at Scale

Engineering at Scale 9 min read

How to handle 100,000 concurrent users

Load balancing, caching, queues, read replicas, connection pooling, autoscaling and load testing: how to build a platform that survives its busiest minute.

PS Prajjwal Sinha Sep 13, 2026

Engineering at Scale

Engineering at Scale 8 min read

Horizontal vs vertical scaling: which should you use?

Scale up or scale out? The trade-offs in cost, limits and downtime, what stateless apps need, and why databases usually grow vertically first, with a worked cost example.

PS Prajjwal Sinha Sep 9, 2026

Engineering at Scale

Engineering at Scale 9 min read

PgBouncer explained: pooling modes, settings and pitfalls

Session, transaction and statement pooling, what breaks in transaction mode, key pgbouncer.ini settings, PgBouncer vs Pgpool-II and managed proxies, and production tips.

PS Prajjwal Sinha Sep 2, 2026

Engineering at Scale

Engineering at Scale 8 min read

Postgres too many connections error: causes and fixes

What 'sorry, too many clients already' means, how to find the culprits in pg_stat_activity, quick relief during an incident, and why raising max_connections isn't the fix.

PS Prajjwal Sinha Aug 21, 2026

Engineering at Scale

Engineering at Scale 9 min read

Redis cache: how it works, and Redis vs Memcached

Why Redis is fast, how TTLs and eviction policies work, how to size memory, when persistence matters for a cache, and how Redis compares with Memcached.

PS Prajjwal Sinha Jul 26, 2026

Engineering at Scale

Engineering at Scale 7 min read

Postgres materialized views: query-level caching

Precompute leaderboards and reports inside PostgreSQL: create and index materialized views, refresh them concurrently, schedule refreshes, and know the alternatives.

PS Prajjwal Sinha Jul 20, 2026

Engineering at Scale

Engineering at Scale 9 min read

How database indexing works, with Postgres examples

B-trees in plain English, reading EXPLAIN ANALYZE, composite, partial and covering indexes, what indexes cost, and adding them to a live Postgres table safely.

PS Prajjwal Sinha Jul 11, 2026

Engineering at Scale

Engineering at Scale 9 min read

Read replicas and database replication explained

How PostgreSQL streaming replication works, synchronous vs asynchronous commits, routing reads in Django, handling replication lag, and replicas for failover.

PS Prajjwal Sinha Jul 8, 2026