diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 2522f4c8c5..353d4e808a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -2771,9 +2771,10 @@ include_dir 'conf.d' levels. This parameter can only be set at server start. - In minimal level, no information is logged for - permanent relations for the remainder of a transaction that creates or - rewrites them. This can make operations much faster (see + The minimal level generates the least WAL + volume. It logs no row information for permanent relations + in transactions that create or + rewrite them. This can make operations much faster (see ). Operations that initiate this optimization include: @@ -2785,19 +2786,20 @@ include_dir 'conf.d' REINDEX TRUNCATE - But minimal WAL does not contain enough information to reconstruct the - data from a base backup and the WAL logs, so replica or - higher must be used to enable WAL archiving - () and streaming replication. + However, minimal WAL does not contain sufficient information for + point-in-time recovery, so replica or + higher must be used to enable continuous archiving + () and streaming binary replication. + In fact, the server will not even start in this mode if + max_wal_senders is non-zero. Note that changing wal_level to - minimal makes any base backups taken before - unavailable for archive recovery and standby server, which may - lead to data loss. + minimal makes previous base backups unusable + for point-in-time recovery and standby servers. In logical level, the same information is logged as - with replica, plus information needed to allow - extracting logical change sets from the WAL. Using a level of + with replica, plus information needed to + extract logical change sets from the WAL. Using a level of logical will increase the WAL volume, particularly if many tables are configured for REPLICA IDENTITY FULL and many UPDATE and DELETE statements are