The SGA Size alert notifies you when its configured condition is met on Oracle instances so you can investigate and respond.
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 Mini DBA evaluates this alert once a minute so changes are detected quickly.
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. For an over-threshold alert, decreasing a threshold makes that severity fire sooner; increasing it tolerates more load or pressure. Set the minor threshold as an early-warning level and the major threshold at the highest acceptable value for the service.
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.