ah, so something like... if the primary ordered transaction 3 < transaction 1, but transaction 2 observes only transaction 1 on the read-only secondary potentially because the secondary orders transaction 1 < transaction 3?
"I think what's going on here is that a read-only transaction against a secondary can observe some transaction T, but also miss transactions which must have logically executed before T."
i was intuitively wondering the same but i'm having trouble reasoning how the post's example with transactions 1, 2, 3, 4 exhibits this behavior. in the example, is transaction 2 the only read-only transaction and therefore the only transaction to read from the read replica? i.e. transactions 1, 3, 4 use the primary and transaction 2 uses the read replica?
The Persistence Infrastructure team develops and operates Discord’s real-time datastore systems that serve the data of Discord's 150M+ monthly active users—including over a trillion messages! We work across multiple systems areas: databases, disk storage and Rust-based data access services. We're a small team whose work has a huge impact on our organization's success and ability to grow.