Oracle-dba-help

After more than 12 years of working with production databases, I have learned that performance problems do not always begin with one terrible query.

Sometimes it is several smaller things happenin...

Redo log problems rarely start with a clean error message. They usually show up as slow commits, archive destinations filling faster than expected, Data Guard apply lag, or batch jobs that suddenly take longer during month-end. By the time someone checks the alert log, the database may already be switching logs too frequently, checkpointing aggressively, or waiting for archiving...

 AWR used to be simple when most databases were single-instance, single-tenant, and all important workload stayed on the primary database.

That world is mostly gone.

Today, one CDB may host multiple PDBs. Reporting may run on Active Data Guard. Read traffic may be pushed toward True Cache. Replication may be handled through GoldenGate or XStream. When performanc...

A PostgreSQL database can look completely healthy until the day you try to restore it.
Backups are available. WAL archiving is enabled. The archive directory has files. Monitoring shows green. Then, during PITR, PostgreSQL throws something like:
could not locate required checkpoint record

or recovery stops before the target time because the WA...

A database incident rarely begins when the monitoring system raises an alert. It usually begins weeks earlier - with an unreviewed execution plan, an ignored capacity trend, an oversized privilege, or a recovery procedure that nobody has tested.