If you are replicating, you want to set this to the maximum number of standby servers you might possibly have. Performance impact when set above zero, but no additional penalty for setting it higher.
- Re: Resetting spilled txn statistics in pg_stat_replication
- pg_basebackup is taking an unusually long time with Postgres 11.3
- Re: [HACKERS] WAL logging problem in 9.4.3?
- Re: WIP/PoC for parallel backup
- [Logical Replication] TRAP: FailedAssertion("rel->rd_rel->relreplident == REPLICA_IDENTITY_DEFAULT || rel->rd_rel->relreplident == REPLICA_IDENTITY_FULL || rel->rd_rel->relreplident == REPLICA_IDENTITY_INDEX"