Compare — Period-over-Period Query Diff

Compare picks two arbitrary time windows and computes per-query deltas: calls, total time, mean time, I/O. Sorts by biggest mover. The whole point is catching "this query was 50ms yesterday and 800ms today" without you having to remember it was 50ms yesterday.

Common comparisons

Last hour versus previous hour catches the most recent regressions — your "what just changed" view. Today versus yesterday at the same time is diurnal-aware: prod traffic at 3pm Tuesday is comparable to 3pm Monday, not 3am. This week versus last week tracks workload growth (and is usually how you spot a slow accumulation that wouldn't trigger any alert). And the custom case is post-deploy versus pre-deploy — pin the deploy timestamp from Annotations and Compare's quick-pick offers "before vs. after" automatically.

Reading the diff

Each row shows the query fingerprint, calls (a → b with percentage change), mean time delta, and total time delta. Color-coded: red worse, green better. Click any query and you get its trend chart with both windows highlighted, which usually makes the cause obvious.

Pair with deploys

Drop an Annotation when you deploy. Compare's quick-pick now offers "before vs. after <your deploy>" — instant deploy regression triage. We sometimes do this with the deploy webhook so it's automatic.