Exception Handling

The persistence module handles exceptions by using the Postgres error reporting infrastructure (ereport). An error message is recorded in the system log for each error condition. In addition, the error is reported to the envelope using Postgres’s built-in error reporting infrastructure.

The following exceptions are reported by this module –

Table 1 Exception Handling

Exception Condition	Exception Code	Scenario	Resulting Outcome
WAL write failure	ERRCODE_FDW_ERROR	On any case the WAL write fails	Transaction terminates
File IO error: write, open and so on	ERRCODE_IO_ERROR	Checkpoint – Called on any file access error	FATAL – process exists
Out of Memory	ERRCODE_INSUFFICIENT_RESOURCES	Checkpoint – Local memory allocation failures	FATAL – process exists
Logic, DB errors	ERRCODE_INTERNAL_ERROR	Checkpoint: algorithm fails or failure to retrieve table data or indexes.	FATAL – process exists