[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"glossary-acid::en":3,"gloss-cluster-acid::en":20,"gloss-next-acid::en":9},{"slug":4,"category":5,"name":6,"definition":7,"meta_desc":8,"faq":9,"schema_markup":9,"related":10},"acid","data-infra","ACID","ACID is an acronym for the four properties a database transaction must guarantee to be considered reliable: Atomicity (a transaction either completes entirely or has no effect at all — no partial updates left behind if something fails midway), Consistency (a transaction only ever moves the database from one valid state to another, never violating defined constraints like foreign keys or uniqueness), Isolation (concurrent transactions don't interfere with each other — one transaction in progress doesn't see another transaction's uncommitted changes), and Durability (once a transaction is committed, it survives a subsequent crash — the data is actually written to durable storage, not just held in memory). Why it matters for AI\u002FSaaS builders: ACID guarantees are what make it safe to build billing, subscription, and any money-touching logic on a relational database without constantly worrying about edge cases like \"what if the server crashes exactly between charging the card and recording the subscription.\" PostgreSQL, MySQL, and virtually every mainstream relational database are fully ACID-compliant; this is a major reason relational databases remain the default choice for a SaaS's core transactional data even in an era full of newer, more specialized data stores. Most AI-adjacent data stores make a different trade-off: many vector databases and NoSQL systems deliberately relax some ACID guarantees (typically consistency or isolation) in exchange for higher write throughput or easier horizontal scaling — a legitimate trade-off for embeddings and event logs, but the wrong trade-off for a customer's subscription record. How it works: transactions are explicitly demarcated (`BEGIN`, then a sequence of statements, then `COMMIT` or `ROLLBACK`), and the database engine handles enforcing all four properties internally — using write-ahead logging for durability and atomicity, locking or multi-version concurrency control (MVCC, which Postgres uses) for isolation, and constraint checking for consistency. Worked example: a SaaS's checkout flow needs to both charge a payment method and create a subscription record — two operations that must both succeed or both fail together, never just one. Wrapping both in a single database transaction (`BEGIN; INSERT INTO payments ...; INSERT INTO subscriptions ...; COMMIT;`) guarantees atomicity: if the server crashes or an error occurs after the payment insert but before the subscription insert, the entire transaction rolls back, leaving no orphaned payment record with no corresponding subscription — a failure mode that would otherwise require fragile manual reconciliation logic to detect and fix after the fact.","ACID is the set of four guarantees (Atomicity, Consistency, Isolation, Durability) that ensure database transactions are processed reliably.",null,[11,14,17],{"slug":12,"name":13},"data-pipeline","Data Pipeline",{"slug":15,"name":16},"postgresql","PostgreSQL",{"slug":18,"name":19},"replication","Replication",[21,25,28,31,35,38,41,44,47,51,54,57],{"slug":22,"category":5,"name":23,"updated_at":24},"ann-search","ANN Search","2026-08-24T02:46:37+00:00",{"slug":26,"category":5,"name":27,"updated_at":24},"backpressure","Backpressure",{"slug":29,"category":5,"name":30,"updated_at":24},"batch-processing","Batch Processing",{"slug":32,"category":5,"name":33,"updated_at":34},"bm25","BM25","2026-08-24T02:46:38+00:00",{"slug":36,"category":5,"name":37,"updated_at":24},"cache","Cache",{"slug":39,"category":5,"name":40,"updated_at":24},"cap-theorem","CAP Theorem",{"slug":42,"category":5,"name":43,"updated_at":24},"change-data-capture","Change Data Capture (CDC)",{"slug":45,"category":5,"name":46,"updated_at":24},"chroma","Chroma",{"slug":48,"category":5,"name":49,"updated_at":50},"chunk-overlap","Chunk Overlap","2026-08-24T03:30:02+00:00",{"slug":52,"category":5,"name":53,"updated_at":24},"columnar-storage","Columnar Storage",{"slug":55,"category":5,"name":56,"updated_at":24},"connection-pooling","Connection Pooling",{"slug":58,"category":5,"name":59,"updated_at":24},"cosine-similarity","Cosine Similarity"]