Investigated three approaches for CH 24.12:
- Inline SETTINGS on ADD PROJECTION: rejected (UNKNOWN_SETTING — not a query-level setting).
- ALTER TABLE MODIFY SETTING deduplicate_merge_projection_mode='rebuild': works; persists in
table metadata across connection restarts; runs before ADD PROJECTION in the SQL script.
- Session-level JDBC URL param: not pursued (MODIFY SETTING is strictly better).
alerting_projections.sql now runs MODIFY SETTING before the two executions ADD PROJECTIONs.
AlertingProjectionsIT strengthened to assert all four projections (including alerting_app_status
and alerting_route_status on executions) exist after schema init.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Adds alerting_projections.sql with four projections (alerting_app_status,
alerting_route_status on executions; alerting_app_level on logs;
alerting_instance_metric on agent_metrics). ClickHouseSchemaInitializer now
runs both init.sql and alerting_projections.sql, with ADD PROJECTION and
MATERIALIZE treated as non-fatal — executions (ReplacingMergeTree) requires
deduplicate_merge_projection_mode=rebuild which is unavailable via JDBC pool.
MergeTree projections (logs, agent_metrics) always succeed and are asserted in IT.
Column names confirmed from init.sql: logs uses 'application' (not application_id),
agent_metrics uses 'collected_at' (not timestamp). All column names match the plan.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
