ClickStack Demo Day (2026-08-28) - Dashboard variables in PromQL and Lucene

Dashboard variables now work in PromQL charts. You get autocomplete for variable references, warnings when a variable doesn't exist or is used incorrectly, and a generated PromQL preview that shows the query with the current selections substituted in, alongside the existing generated SQL panel. Lucene variables got an exact-match form. Field:$var expands to Field:("A" OR "B"), which is substring matching, so filtering ServiceName by a variable holding "add" and "cart" also matched every service whose name merely contains those strings. Quoting the variable instead, Field:"$var", rewrites to (Field:"A" OR Field:"B") and preserves exact-match semantics, consistent with how a quoted non-variable field match already behaves. The autocomplete points this out. Drilling through from a chart tooltip or a table row to the search page now expands variables and macros first. The search page doesn't understand variables, so the old behaviour sent a raw variable reference through and produced wrong results or a query error. Editing a filter and pressing escape now asks before discarding your changes, rather than throwing them away to close a tooltip. Dashboard variables shipped to production this week, with public docs, and the feature toggle is gone. Part of the ClickStack Demo Day series. See the full post at https://clickhouse.com/docs/use-cases/observability/clickstack/demo-days/2026/2026-08-28