TIL
Short notes on things I learned, each linking the best source I know.
- 08/23W-TinyLFU lets new cache entries prove themselves in a small LRU windowcachingA small LRU window lets new keys earn their way into the cache.
- 08/11A cut-off Raft leader can keep appending, but it can never commitraftWhy Raft's vote rule checks the last term before log length.
- 08/11In Raft, an entry stored on a majority of nodes can still be erasedraftWhy a Raft leader only counts replicas for its own term's entries.
- 08/11The end-to-end argument repeats at every layernetworkingEvery middle layer has its own two ends and its own retry loop.
- 07/31A database page fragments because rows aren't deleted in the order they were writtenpostgresRows are allocated like a stack but freed like a heap.
- 07/31A join gets expensive when the filter needs the join's outputsqlThe hard case is when the filter needs the join's own result.
- 07/31A slotted page lets rows move, but only within the pagepostgresWhy databases address rows as (page, slot), and the limit that leaves.
- 07/30Fencing keeps you correct; a worker aborting itself only saves moneylockingTwo responses to a lost lease, and why only one is about safety.
- 07/18Solomonoff's predictor can't dodge its bound by oscillatinginductionThe expected daily error can't go negative, so it has to shrink.
- 07/04Optimistic concurrency control makes the same bet as speculative executionconcurrencyGuess, then check: the same bet in databases, CPUs and LLM decoding.