Two-layer fix for the TZ drift that caused stats reads to miss every row
when the JVM default TZ and CH session TZ disagreed:
- Insert side: ClickHouse JDBC 0.9.7 formats java.sql.Timestamp via
Timestamp.toString(), which uses JVM default TZ. A CEST JVM shipping
to a UTC CH server stored Unix timestamps off by the TZ offset (the
triage report's original symptom). Pinned JVM default to UTC in
CameleerServerApplication.main() — standard practice for observability
servers that push to time-series stores.
- Read side: stats_1m_* tables now declare bucket as DateTime('UTC'),
MV SELECTs wrap toStartOfMinute(start_time) in toDateTime(..., 'UTC')
so projections match column type, and ClickHouseStatsStore.lit(Instant)
emits toDateTime('...', 'UTC') rather than a bare literal — defence
in depth against future refactors.
Test class pins its own JVM TZ (the store IT builds its own
HikariDataSource, bypassing the main() path). Debug scaffolding from
the triage investigation removed.
Greenfield CH — no migration needed.
Verified: 14/14 ClickHouseStatsStoreIT green, plus 84/84 across all
ClickHouse IT classes (no regression from the JVM TZ default change).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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