Workflow [PR], commit [daa8240]

Summary: ✅

AI Review

Summary

This PR fixes a flaky stateless test by replacing toUUID with toUUIDOrNull when parsing ZooKeeper node suffixes and filtering out NULL UUIDs before joining system.databases. The change is minimal, targeted, and correctly addresses the reported parallel-test failure mode without altering product behavior.

ClickHouse Rules

Final Verdict

• Status: ✅ Approve

Root cause analysis

The test scans all children of /clickhouse/databases/ in ZooKeeper and calls toUUID on each path suffix, assuming they are all UUIDs. This assumption is wrong — several other tests create Replicated databases with literal (non-UUID) ZooKeeper paths under that prefix.

The specific entry d2_test_8e50qzr4 that caused the failure comes from 03784_bad_base_backup.sh (line 32):

CREATE DATABASE d2_$CLICKHOUSE_DATABASE ENGINE = Replicated('/clickhouse/databases/d2_$CLICKHOUSE_DATABASE', 's0', 'd0');

Three other tests also create non-UUID entries directly under /clickhouse/databases/ via the {database} macro (which expands to the literal database name):

• 03362_create_table_after_truncate_replicated_database.sql
• 03655_keeper_map_alter_comment.sql
• 03321_create_table_as_replicated_engine_args.sql

These are all legitimate uses — the Replicated database engine does not require UUID-based paths. The fix is to use toUUIDOrNull in the scanning query so it gracefully skips non-UUID entries.