Five types of scans every backend dev should recognise
Seq scan, index scan, index-only scan, bitmap heap scan, TID scan. When the planner picks each, and what it means when you see the wrong one.
Seq scan, index scan, index-only scan, bitmap heap scan, TID scan. When the planner picks each, and what it means when you see the wrong one.
shared_buffers, work_mem, effective_cache_size, and five more — what they really do, how to size them, and which defaults are still stuck in 2008.
If your index has every column the query needs, the database never has to fetch the row. Here's how to recognise the opportunity — and the storage trade.