ClickStack Demo Day (2026-08-21) - Metric formulas in the chart editor

Metric charts can now do arithmetic. Series in a chart are labelled A, B, C, and a formula row lets you build a derived series from them, like A / (A + B + C) * 100 for a queue utilization rate. You can add several formulas to one chart, choose whether to show the operand series alongside the result or just the formula, and mix series from different metrics. Alerts work on formulas too. The formula is compiled from a validated AST into the composed metric query, so ClickHouse computes it in a single scan. Missing operands count as zero and every division denominator is wrapped in nullif(..., 0), so a zero denominator renders as a gap rather than a zero or an error. The input takes letter references and simple arithmetic, not arbitrary SQL. Unknown series refs, malformed expressions and constant-only expressions are caught live in the editor and block save, so an invalid expression never reaches ClickHouse. Part of the ClickStack Demo Day series. See the full post at https://clickhouse.com/docs/use-cases/observability/clickstack/demo-days/2026/2026-08-21