An ETag costs nothing to emit and saves the response body only if clients actually send the conditional header back. The write side is where ETag earns its…
An exact key miss with no restore keys means starting from nothing, which for a node_modules cache is the difference between four seconds and ninety. The restore key…
A generator can be iterated once, and the second foreach over the same instance throws rather than returning nothing. Returning a generator from a method is therefore a…
A lab tool measures one load on one connection, and the metric that counts is the 75th percentile of real visitors over 28 days. First Input Delay cannot…
A composite index serves any query using a leftmost prefix of its columns, which means three separate indexes are frequently one index somebody did not notice. The gap…
Five sequential API calls of 180 milliseconds each is nine hundred milliseconds of a request spent waiting, and they had no dependency on each other. Naming the requests…
Three retries per caller sounds modest and means four times the load on a struggling dependency, which is the opposite of what a retry is for. A budget…
An index containing every column a query needs answers it without reading the table, which on a wide row is the difference between one page read and two.…