Pglesslog is a set of tools to reduce the size of PostgreSQL archive log. PGlesslog consists of the following programs.

pg_compresslog - This program is used to reduce the size of WAL files when WAL is archived. This is done by replacing full page writes (physical log) of WAL records with corresponding incremental logs. Such replacement is done only for WAL records with "removable" mark. Removable mask is described in xlog.c code. Because incremental log is extremely smaller than full page writes, this program reduces WAL file size when archived. This command should be specified as archive_command in postgresql.conf. This command also removes page headers by changing page size from 8kB to 16MB, which are restored by pg_decompresslog.

pg_decompresslog - This command restores page headers and adds dummy data to restore the physical log record, finally restoring the LSN of each log record and restores the page size to be used in the archive recovery. This command should be specified as restore_command in recovery.conf. Size of the file will be the same as original WAL segment files before archived. "NOOP" WAL record will be used for the filler, which will be neglected by redo functions at the recovery.