The slow log ranks by individual duration, so a query taking two seconds once appears above one taking 40 milliseconds two hundred thousand times — and the second…
The cache expired at noon and the database fell over at 12:00:01. A lock, a two-tier expiry, jittered TTLs, and versioned keys — in that order of importance.
Profiling a slow WordPress page usually starts with guessing which plugin is responsible, and there is a command that answers it directly. Drilling from stage to hook to…
Loading the extension slows execution substantially even with no session and no profiler running, because it installs hooks into the engine. The trigger form means the profiler runs…
EXPLAIN shows the plan the optimiser chose and its estimates, and the estimates are frequently wrong — a query planned for 40 rows that reads 400,000 looks fine…
A table sorted by inclusive time puts the entry point at the top and tells you nothing; sorted by exclusive time it hides the structure. The graph shows…
8.0 went GA in April and the correlated subquery can retire. The plans before and after, the recursive CTE that replaces a loop, and the upgrade nobody expects.
An instrumenting profiler records every function call, which changes the timings it is measuring — small fast functions look disproportionately expensive because the overhead is per call. Sampling…