"<WARNING> Could not estimate database size. Switching to exhaustive mode"?"
Environment
Vertica Analytics Database v24.4.0
Situation
User is receiving more than 3000+ warning messages in 1 node cluster: "<WARNING> Could not estimate database size. Switching to exhaustive mode"?"<WARNING> Sampling excessively. Sample size is [10000]. Total cells [282]"
In the logs we were able to find:
2026-02-20 08:00:43.495 Init Session:0x890ddffff6c0-a000000589c325 [Txn] <INFO> Begin Txn: a000000589c325 'executing audit'
2026-02-20 08:00:43.496 Init Session:0x890ddffff6c0-a000000589c325 [EE] <WARNING> Sampling excessively. Sample size is [10000]. Total cells [51105]
2026-02-20 08:00:43.496 Init Session:0x890ddffff6c0-a000000589c325 [EE] <WARNING> Could not estimate database size. Switching to exhaustive mode
Based on the log entries, these warnings are generated by Vertica’s internal audit size-estimation process, which is invoked during query planning and metadata validation. When Vertica performs internal size estimation during audit processing, it first attempts to use sampling. If the sample does not provide a sufficiently reliable estimate, Vertica automatically switches to a full evaluation to ensure accuracy. When that fallback occurs, the informational warnings shown in the log are generated.
The reason this is seen multiple times is that the integration workload repeatedly performs metadata and table validation operations. Each of those operations internally triggers a size-estimation audit query, which is why the warning appears several times in close succession.
The messages reflect normal internal behavior during audit-related size estimation and are not caused by application errors. In the logs provided, there are no query errors and no signs of data corruption.
User confirmed that they are running regularly AUDIT/AUDIT_LENGTH to inform our clients about their data usage. Which is leading to spike to CPU usage.
