“wal_level” controls how much information is written to the WAL log

"WAL_LEVEL" parameter determines how much information is written to the WAL and "WAL_LEVEL" parameter information as follows:

1. Minimal - the Default

          - Suitable for Crash recovery only. WAL archival or streaming Replication can't be enabled.

          - Some Operations like CREATE INDEX are faster because WAL Logging can be skipped.

          - Was previously Controlled by archive_mode=off

   

2. archive

            - Allows WAL archival and Streaming Replication

            - Hot Standby not allowed in the Standby

            -  Was previously Controlled by archive_mode=on

3. Hot_standby

            - Like 'archive',but adds an extra information about running transactions.

            - Allows hot Standby mode in Standby Servers.