Easy Learn
A complete beginner-to-production guide to data modelling: what a data model is, its history from Codd to NoSQL and cloud-native polyglot persistence, the three-schema architecture (conceptual, logical, physical), core vocabulary (entities, attributes, relationships, keys, schema, constraints, normalisation, cardinality, domains, weak entities), how models turn into SQL, JPA entities and B-Tree…
A complete, beginner-friendly walk-through of pessimistic locking: how databases stop two people from stepping on each others work, explained from first principles with diagrams, Java code, and real production stories. Covers the shared-notebook analogy that captures the entire spirit of pessimistic locking; a short history from the early 1970s IBM…
A complete, beginner-to-production guide to database denormalization: trading a little bit of tidiness for a lot of speed, with diagrams, Java code, and real stories from Netflix, Amazon, Uber, and Instagram/Meta. Covers the notebook analogy that captures the entire spirit of denormalization; a short history from Edgar F. Codd 1970…
A complete beginner-to-production walkthrough of document databases: what a document actually is, how MongoDB, Couchbase, Amazon DocumentDB, Firestore and Cosmos DB store data as flexible JSON or BSON records instead of rigid rows and columns, and why that model unlocks developer speed and horizontal scale. Covers the history from 1970s…
A complete, beginner-to-production guide to durability — the D in ACID: how databases make sure your data survives crashes, power failures, and disasters. Covers the origin of ACID (H�rder & Reuter 1983, IBM System R, Jim Gray, ARIES); a seven-step evolution timeline from 1970s file-based storage through WAL, RAID, multi-AZ…
A complete beginner-to-production guide to graph databases — the storage engines that treat relationships as first-class data instead of hiding them behind joins. Nineteen sections walk from graph theory's 1736 origins (Euler's Königsberg bridges) through the modern property graph model (nodes, edges, labels, properties, paths, traversals), the RDF alternative, the…
A complete beginner-to-expert guide to the hot partition problem — the moment a “perfectly scaled” distributed cluster still collapses under a single overloaded partition while the rest sits idle. Twenty-two sections walk from history and first principles (partitioning, sharding, hashing, skew) through architecture, step-by-step failure narratives, detection strategies, and every…
Hot partitions are the single most common way sharding fails in production: a distributed database is technically split across dozens of shards, yet one shard receives a wildly disproportionate share of the traffic or data — turning the whole cluster back into a one-machine bottleneck while every other node sits…
A beginner-to-production guide to SQL injection — the trust-boundary flaw that has sat on the OWASP Top 10 for two decades. Covers the single-quote break-out and login-bypass mechanics; the family tree of in-band, blind, out-of-band, and second-order attacks; why parse-then-bind (prepared statements) fixes it categorically; ten defense layers used in…
A ground-up tour of transaction isolation — the “I” in ACID — from the joint-account race condition, through dirty reads, non-repeatable reads, phantom reads, lost updates, and write skew; the four SQL isolation levels (Read Uncommitted, Read Committed, Repeatable Read, Serializable) and what each one trades away for speed; pessimistic…