If your system smells trouble, it makes sense to inspect the log to see what is going on. The important point is this: not all log entries are created equal. PostgreSQL has a hierarchy of log entries that range from DEBUG messages to PANIC.
For the administrator, the following three error levels are of great importance:
- ERROR
- FATAL
- PANIC
ERROR is used for problems such as syntax errors, permission-related problems, and more. Your log will always contain error messages. The critical factor is this—how often does a certain type of error show up? Producing millions of syntax errors is certainly not an ideal strategy for running a database server.
FATAL is scarier than ERROR; you will see messages such as could not allocate memory for shared memory name or unexpected walreceiver state. In other words, these error messages are already really scary and will...