[vdekrijger]

Problem

Staff can change the native events cluster host at runtime through an instance setting. Each host change caches one more ClickHouse connection pool per worker, and the old pools keep their sockets open indefinitely.

Changes

• Changing the native host retires the previous host's pool.
• Idle connections close at once. Each in-flight connection closes when its query finishes, so running queries are not interrupted.
• Other workloads keep the existing cached pool factory.

How did you test this code?

Test rationale: test_native_events_pool_is_retired_when_the_host_changes in the existing connection tests switches the host, checks that a new pool serves it, and checks that a client returned to the old pool disconnects.

Release status

• No feature flag controls this change

Docs update

None.

🤖 Agent context

Autonomy: Human-driven (agent-assisted).
Agent: Claude Code, model claude-opus-5-5.

Split out of #116838 so each piece of the native events cluster rollout reviews on its own. Skills: stacking-prs, writing-tests, writing-code-comments, writing-pr-descriptions.

[trunk-io]

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[github-actions]

🤖 CI report

⚠️ Trunk lane — backend Python lane

This PR is assigned to the backend Python lane. It runs backend Python tests and may merge in parallel with PRs in other lanes.

✅ Duplication (Python) — clean

New Python code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

✅ Duplication (TypeScript) — clean

New TypeScript code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

[trunk-io]

   

View Full Report ↗︎ ⋅ Docs

[posthog]

PostHog Review · Standard · reviewed 18f21cd: no findings.

This Standard review started from the posthog-review label. Comment @posthog review --deep for a Deep review, or @posthog help to see all commands.

[vdekrijger]

Superseded by #122489, which merged on Oct 26 and routes events_json reads to the events cluster with one rule instead of the per-query opt-in this PR carried. Closing; the branch stays.