Write a subquery using the syntax metric[<range>:<resolution>] to evaluate a range vector at a reduced resolution for efficiency
Apply the offset modifier to compare the current value against the same metric from 7 days ago using metric offset 7d
Compute a ratio of current to prior-week values with a division expression and multiply by 100 for a percentage change panel
Wrap the expression in a Grafana variable template to allow dynamic range and offset selection from the dashboard UI
Use the @ modifier to anchor a query to a fixed Unix timestamp for point-in-time comparisons in postmortem dashboards
Known gotchas
Subquery resolution must be explicitly chosen; using too fine a resolution against a long range is expensive and can cause query timeouts in Prometheus
The offset modifier applies to the entire instant or range vector selector, not to the full expression; parentheses must be used carefully to apply offset to subexpressions
The @ modifier and offset modifier cannot both be used on the same selector in some Prometheus versions; test compatibility with the target Prometheus version
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claude mcp add --transport http waymark https://mcp.waymark.network/mcp