Software, systems, cloud and AI — with a focus on the reasoning behind modern technology.https://buildwithreason.comen-us© 2026 Kartik Mavanihttps://buildwithreason.com/writing/rag-is-not-a-databasehttps://buildwithreason.com/writing/rag-is-not-a-databaseRetrieval-augmented generation is usually built as though a vector store were a database with fuzzy matching. It is a ranking system, and treating it as one changes almost every design decision.Thu, 03 Sep 2026 00:00:00 GMTAI EngineeringRAGRetrievalLLM ApplicationsSearchKartik Mavanihttps://buildwithreason.com/writing/distributed-lockshttps://buildwithreason.com/writing/distributed-locksA distributed lock cannot promise mutual exclusion, because it cannot control the process holding it. What it can do is still useful — provided you know which of the two problems you have.Fri, 28 Aug 2026 00:00:00 GMTDistributed SystemsCoordinationConsistencyReliabilityRedisKartik Mavanihttps://buildwithreason.com/writing/kafka-orderinghttps://buildwithreason.com/writing/kafka-orderingKafka gives you ordering per partition. Almost every ordering bug in production comes from a gap between that guarantee and the one people believed they had.Thu, 20 Aug 2026 00:00:00 GMTDistributed SystemsKafkaMessagingIdempotencyConsistencyKartik Mavanihttps://buildwithreason.com/writing/what-happens-beneath-the-abstractionshttps://buildwithreason.com/writing/what-happens-beneath-the-abstractionsEvery abstraction is a bet about what you will never need to know. Understanding the bet is most of what separates engineers who can debug a system from engineers who can only operate one.Wed, 12 Aug 2026 00:00:00 GMTEngineering ThinkingAbstractionsSystems ThinkingArchitectureKartik Mavani