In Postgres 17 doc, for wal_compression parameter it's written:
"Turning this parameter on can reduce the WAL volume without increasing the risk of unrecoverable data corruption" If wal_compression = on then when a full page is written in the wal, it will be compressed. What I do not understand is that the wal file keeps the same size 16Mb. What is the interest to activate wal_compression?
A WAL file contains some records. Usually a lot of records. If a record is compressed, it will take less space in the WAL file. Hence, this WAL file will contain more records, and you will need less WAL files for the same activity.
