Advisor check: Postgres WAL retention check¶
Description¶
This check analyses the number of WAL files being retained in the pg_xlog or pg_wal directory, depending on the version of Postgres being checked, and reports the number of WAL files and the disk space they consume.
Additionally, the check provides information on the number of wal_keep_segments or wal_keep_size configured depending on the version of Postgres. A calculation is performed against the parameters mentioned, and the potential disk space used as a result of the parameter values and wal_segment_size for the running cluster.
Resolution¶
There are various reasons WAL files can accumulate in the WAL directory and it is up to the administrator to decide if the reported number of WAL files is a concern.
Typically, WAL file accumulation occurs when the following situations arise:
- A replica using replication slots is offline and the replication slot has not been removed.
- Archiving of WAL files is failing and the WAL files are being retained until resolved.
- Wal_keep_segments or wal_keep_size has been configured to a value other than 0.
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