Bishal Regmi — Backend Engineering BlogWeekly deep dives on backend engineering, databases, distributed systems, and AI infrastructure.https://bishalregmi.com.np/Designing a Notification System: Fan-Out and Delivery Guaranteeshttps://bishalregmi.com.np/blog/epic-notification-systems-fan-out-guarantees/https://bishalregmi.com.np/blog/epic-notification-systems-fan-out-guarantees/Patterns and guarantees for building notification systems that scale: fan-out strategies, retries, idempotency, and delivery guarantees.Sat, 04 Jul 2026 00:00:00 GMTnotificationssystem-designPostgreSQL Query Planner Internals: How the Cost-Based Optimizer Chooses a Planhttps://bishalregmi.com.np/blog/postgresql-query-planner-internals/https://bishalregmi.com.np/blog/postgresql-query-planner-internals/An overview of PostgreSQL's planner: cost model, statistics, join ordering, and why the wrong plan gets chosen sometimes.Sat, 04 Jul 2026 00:00:00 GMTpostgresqlbackendperformanceWhy your database connection pool is probably misconfiguredhttps://bishalregmi.com.np/blog/why-connection-pools-matter/https://bishalregmi.com.np/blog/why-connection-pools-matter/Connection pools look simple until your app falls over at 3am. Here's the math behind sizing them correctly, and the mistakes that get everyone eventually.Sat, 04 Jul 2026 00:00:00 GMTpostgresqlbackendperformanceRedis Cluster: The 16384 Slots and the Gossip Beneathhttps://bishalregmi.com.np/blog/redis-cluster-the-16384-slots-and-the-gossip-beneath/https://bishalregmi.com.np/blog/redis-cluster-the-16384-slots-and-the-gossip-beneath/A deep dive into Redis Cluster's internals: hash slots, gossip protocol, resharding, MOVED/ASK redirects, and failover mechanics.Sat, 04 Jul 2026 00:00:00 GMTredisclusterdistributed-systemshigh-availabilitycachingIdempotency keys: the one thing that saves you when a webhook fires twicehttps://bishalregmi.com.np/blog/idempotency-keys-save-you-at-3am/https://bishalregmi.com.np/blog/idempotency-keys-save-you-at-3am/Payment gateways retry. Networks drop responses after the work already happened. Here's how idempotency keys stop double charges without slowing anything down.Sat, 20 Jun 2026 00:00:00 GMTpaymentsreliabilitybackendFrom ILIKE '%query%' to search that feels instanthttps://bishalregmi.com.np/blog/from-ilike-to-real-search/https://bishalregmi.com.np/blog/from-ilike-to-real-search/LIKE queries work fine until your table grows. The real path from a slow sequential scan to search that returns results as you type.Sat, 06 Jun 2026 00:00:00 GMTpostgresqlsearchbackendperformance