Use the SGA Size alert in Mini DBA to monitor Oracle instances and make this condition visible before it becomes a wider database incident.
Mini DBA describes this alert as: System Global Area (SGA) memory usage Use this alert to monitor SGA size during tuning Adjust sga_target or sga_max_size parameters as needed The default evaluation frequency is Minute, so the alert is intended to be close enough to operational reality for live triage.
This alert helps detect memory pressure and cache efficiency problems. Low cache effectiveness or high memory pressure increases physical I/O, query latency, and the chance that a workload will become unstable during busy periods.
Enable it on any monitored Oracle instance where this condition would require an administrator to investigate or communicate with the application team. Tune noisy development systems after you have a short baseline.
Threshold meaning: GB used. Major threshold: 100 GB. Minor threshold: 80 GB. Comparison direction: "over". Use higher thresholds on batch-heavy, development, or intentionally bursty systems where brief pressure is expected. Use lower thresholds on latency-sensitive production systems, small instances with little headroom, and services with strict recovery or availability commitments.
Check memory configuration, cache hit indicators, top memory consumers, and host pressure. Remove unnecessary competing services, tune query memory grants or work areas, adjust engine memory settings, and add RAM or resize the service tier when the working set has outgrown the instance.
If the alert creates repeated noise, review whether it is enabled on the correct instances, whether maintenance windows are configured, and whether the minor and major routes match the real business impact. Keep enough history to prove the new setting before changing it broadly.