Huge pages can increase the amount of memory covered by each cached address translation. They can reduce translation overhead for suitable workloads, but the result depends on access patterns and hardware. A large allocation alone does not prove frequent TLB misses, and fewer pages needed to describe a working set does not mean those translations all fit in the processor’s TLB. ...
A cache policy needs a behavioral test, not just a header-presence check. Two responses can both contain max-age yet behave differently because one also requires validation or prohibits storage. The request matters too: a browser can bypass an otherwise reusable copy without changing the origin’s response policy or deleting an older cached entry. ...
EXPLAIN describes a PostgreSQL execution plan; EXPLAIN ANALYZE also executes the statement and measures its work. The useful comparison is between estimated rows and observed rows at the same node. Neither number is a verdict by itself: an estimate is a model, while a measurement describes one execution under particular data, cache, concurrency, and instrumentation conditions. ...
pg_stat_statements groups statement executions and accumulates their costs. It can identify a frequently executed short query whose total time is substantial, as well as an individually slow query. These are different questions. Neither ranking alone proves which change will improve application latency, and execution time is not the same as CPU consumption, storage latency, or end-to-end request duration. ...
TCP’s header has a 16-bit receive-window field. Window scaling lets established connections interpret that field using a shift negotiated during setup, allowing a receiver to advertise more than 65535 bytes of space. The two directions can use different shifts. The extension enlarges the encoding of receive-window information; it does not directly enlarge every buffer or guarantee that a sender will keep that much data in flight. ...
A cache stampede occurs when concurrent misses cause redundant work against the same dependency. Synchronized expiration is one trigger, but eviction, a cold deployment, or cache unavailability can create the same burst. A single popular key can be enough. The useful question is how many rebuilds reach the source while one result is still being computed. ...
Nagle’s algorithm reduces small TCP segments by holding additional short data while earlier data remains unacknowledged, unless enough data accumulates for a full segment. Delayed acknowledgment is a separate receiver behavior that can postpone an ACK briefly. The interaction matters when an application sends a request in multiple small writes and the peer needs the later bytes before producing a response. ...
An index trades storage and write work for a possible reduction in read work. A full scan can win when the table is small or a predicate selects much of it, but neither row count nor selectivity decides alone. Projection, ordering, caching, row width, and available access paths change the comparison. Start with the query’s actual result contract. ...