CNS-138: console: distinct query history empty state when statement logging sampling is off

[jubrad]

https://linear.app/materializeinc/issue/CNS-138/console-distinct-empty-state-when-the-statement-logging-sample-rate-is

Problem

Query history is backed by statement logging, which an operator can turn off by setting the sample rate to 0. When that happens the console showed the generic filter-oriented "No results found." empty state, so the user could not tell that sampling is off from their filters being too narrow.

Solution

• New API module console/src/api/materialize/query-history/statementLoggingMaxSampleRate.ts reads SHOW statement_logging_max_sample_rate, following the existing maxReplicasPerCluster.ts pattern. The effective rate is min(session statement_logging_sample_rate, system statement_logging_max_sample_rate), so a zero cap is a hard opt-out and reading the cap alone is enough to detect it.
• QueryHistoryList renders a distinct SamplingDisabledState when the result set is empty and the cap is 0. The copy names both ways to raise it: ALTER SYSTEM SET statement_logging_max_sample_rate, and the Materialize operator's Helm chart values for self-managed. The filter-oriented empty state is unchanged for a non-zero rate.

The new query is gated on enabled: isEmpty, so it never runs (and never delays) the path that renders rows.

Testing

console/src/api/materialize/query-history/statementLoggingMaxSampleRate.test.ts snapshots the compiled query. Two new cases in QueryHistoryList.test.tsx cover both empty-state branches. While adding them I found DEFAULT_FETCH_QUERY_LIST_HANDLER never matched anything: the schema defaults dateRange to a window ending at new Date(), so its separate queryHistoryListSchema.parse(...) produced different filters than the PARSED_DEFAULT_SCHEMA_VALUES the component is rendered with. The handler now reuses the same parsed value.

Notes for the reviewer

• Depends on CNS-137 (CNS-137: un-gate the query history view in self-managed console builds #38407), which un-gates the query history view in self-managed builds. Nothing here references code that PR introduces, but this empty state is only reachable in self-managed once CNS-137: un-gate the query history view in self-managed console builds #38407 lands and deploys.
• The Helm chart value referenced in the copy comes from CNS-136 (CNS-136: expose statement logging sample rate in the operator chart #38406). The message deliberately names no specific chart key, so it stays accurate regardless of what that PR settles on.
• The message is shown in both deployment modes and mentions Helm only in a self-managed-qualified sentence, rather than branching on AppConfigSwitch.

🤖 Generated with Claude Code

[leedqin]

Also have a PR for this : #36533