Crash recovery is the PostgreSQL subsystem that saves us, should the server crash or fail as part of a system crash.
It's good to understand a little about it and to do what we can to control it in our favor.
If PostgreSQL crashes, there will be a message in the server log with the severity level of
PANIC. PostgreSQL will immediately restart and attempt to recover using the transaction log or
Write-Ahead Log (WAL).
The WAL consists of a series of files written to the
pg_xlog subdirectory of the PostgreSQL
data directory. Each change made to the database is recorded first in WAL, hence the name "write-ahead" log, as a synonym of "transaction log". When a transaction commits, the default—and ...