Indexing
3 engineering logs on Indexing. Newest first.
- Why your index is not being used, and why the planner is usually right
The index exists and EXPLAIN still says sequential scan. A field guide to sargability, stale statistics, the leftmost prefix rule, and the cost settings that make a planner reject an index it should have chosen.
- The RUM Conjecture: You Cannot Optimize Reads, Updates, and Memory at Once
How the RUM Conjecture explains real-world database trade-offs between read latency, write throughput, and memory overhead across B-Trees, LSM-Trees, and hash indexes.
- Shazam finds songs by voting on time offsets, not by comparing audio
How Shazam's fingerprinting works according to the published Wang 2003 paper: constellation maps, combinatorial peak pairing into 32-bit hashes, and the offset histogram that turns song matching into counting.