ServiceControl version 6.20 changes the RavenDB search engine that is used for newly created databases. Existing error and audit instances are not modified by the upgrade. Monitoring instances are not affected.
New databases use the Lucene search engine
Databases created by version 6.20 or later use the Lucene search engine for their indexes instead of Corax. Lucene indexes are smaller, use less memory, and perform better for the ServiceControl workload.
Databases created by earlier versions keep the search engine they were created with, typically Corax. The upgrade does not switch existing databases to Lucene because doing so triggers a full rebuild of all indexes. On very large databases the rebuild can take days depending on the available compute, and ingestion and indexing rates are degraded while it runs.
Indexes still using Corax are reported
After upgrading, error and audit instances whose indexes still use Corax:
- log a warning at every start-up listing the affected indexes
- report a failing custom check,
Error Database Search EngineorAudit Database Search Engine, in ServicePulse
The custom check is informational. The instance continues to operate normally on Corax and the check can be left failing until a migration is planned. To migrate existing indexes to Lucene and clear the check, follow the migration procedure during a maintenance window.
Previously migrated and locked indexes
Indexes that were already migrated to Lucene and locked, as described in the troubleshooting guide, remain locked and on Lucene after the upgrade. No action is required for them; the custom check only reports indexes that still use Corax.