Abstract Algorithms

Category

dynamodb

2 articles across 2 sub-topics

ACID Transactions in Distributed Databases: DynamoDB, Cosmos DB, and Spanner Compared

TLDR: ACID transactions in distributed databases are not equal. DynamoDB provides multi-item atomicity scoped to 25 items using two-phase commit with a coordinator item, but only within a single region. Cosmos DB wraps partition-scoped operations ins...

Apr 5, 2026•38 min read

Architecture Patterns(1)

The Dual Write Problem in NoSQL: MongoDB, DynamoDB, and Cassandra

TLDR: NoSQL databases trade cross-entity atomicity for scale — and every database draws that atomicity boundary in a different place. MongoDB's boundary is the document (pre-4.0) or the replica set (4.0+ multi-doc transactions). DynamoDB's boundary i...

Apr 5, 2026•37 min read