Oracle Database / SQL Performance & Memory
Investigate log file sync waits through commit behavior
High commit latency may involve redo flush latency, frequent small commits or scheduling pressure. Capture timed wait deltas and workload context.
Environment and inputs: Oracle Database 19c baseline · SQL*Plus-compatible SQL unless RMAN, DGMGRL, ADRCI or a host shell is specified. Check release, patch level, edition and container first.
Start with this diagnostic
Use the stated SQL, RMAN, DGMGRL or host shell and replace sample names with approved targets. DBA and V$ views need authorized catalog access in the correct container. Do not grant broad privileges for an example.
SELECT event, total_waits, time_waited_micro FROM v$system_event WHERE event IN ('log file sync','log file parallel write');Read the result
Totals are cumulative for the instance. Comparing interval changes can help separate foreground commit waits from redo-write behavior, but they are not a complete causal test.
Resolve and verify
Correlate commit rate, redo storage latency and host scheduling. Review overly chatty commit boundaries while preserving durability and business semantics.
Operational precautions
Do not disable durable commit guarantees to improve a metric or compare cumulative averages across unrelated time windows.