Can I delete WAL files?
WAL files are incremental, so the simple answer is: You cannot throw any files out. The solution is to make a new base backup and then all previous WALs can be deleted.
How does Postgres WAL work?
Write-Ahead Logging ( WAL ) is a standard method for ensuring data integrity. Using WAL results in a significantly reduced number of disk writes, because only the log file needs to be flushed to disk to guarantee that a transaction is committed, rather than every data file changed by the transaction.
What are SHM and WAL files?
The -shm file contains an index to the -wal file. The -shm file improves performance when reading the -wal file. If the -shm file gets deleted, it get created again during next database access. If checkpoint is run, the -wal file can be deleted.
How can I solve PostgreSQL problem after deleting Wal?
If you want to remove WAL, either let the server do it at CHECKPOINT time, or use pg_archivecleanup. Note that the server will remove WAL is no longer needs automatically, unless: (in 9.4) It’s still needed by a replication slot.
Why is Wal retention so important in PostgreSQL?
WAL retention is a very important topic for PostgreSQL database management. But very often we come across DBAs getting into surprise situations such as: 1. Several TBs of WALs piled up in archive destination 2. WALs filling up pg_wal/pg_xlog directory due to failing archive 3. Necessary WALs are no longer preserved
What is the Wal file in PostgreSQL called?
Changes that happen to the data managed by the PostgreSQL server are serialized into replayable deltas and written out as an ordered sequence of files called the “Write Ahead Log”, or WAL.
What happens if archive script fails in PostgreSQL?
Archival failures: If the archive script fails for a certain WAL file, Postgres will retain it and keep retrying until it succeeds. In the meantime, new WAL files will keep getting created. Ensure that your WAL archival processes are not broken, and can keep up with the WAL creation rate.