diff options
| -rw-r--r-- | doc/src/sgml/config.sgml | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 8827685dd73..afe01fa4929 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -2754,9 +2754,10 @@ include_dir 'conf.d' levels. This parameter can only be set at server start. </para> <para> - In <literal>minimal</literal> 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 <literal>minimal</literal> 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 <xref linkend="populate-pitr"/>). Operations that initiate this optimization include: <simplelist> @@ -2768,19 +2769,20 @@ include_dir 'conf.d' <member><command>REINDEX</command></member> <member><command>TRUNCATE</command></member> </simplelist> - But minimal WAL does not contain enough information to reconstruct the - data from a base backup and the WAL logs, so <literal>replica</literal> or - higher must be used to enable WAL archiving - (<xref linkend="guc-archive-mode"/>) and streaming replication. + However, minimal WAL does not contain sufficient information for + point-in-time recovery, so <literal>replica</literal> or + higher must be used to enable continuous archiving + (<xref linkend="guc-archive-mode"/>) and streaming binary replication. + In fact, the server will not even start in this mode if + <varname>max_wal_senders</varname> is non-zero. Note that changing <varname>wal_level</varname> to - <literal>minimal</literal> makes any base backups taken before - unavailable for archive recovery and standby server, which may - lead to data loss. + <literal>minimal</literal> makes previous base backups unusable + for point-in-time recovery and standby servers. </para> <para> In <literal>logical</literal> level, the same information is logged as - with <literal>replica</literal>, plus information needed to allow - extracting logical change sets from the WAL. Using a level of + with <literal>replica</literal>, plus information needed to + extract logical change sets from the WAL. Using a level of <literal>logical</literal> will increase the WAL volume, particularly if many tables are configured for <literal>REPLICA IDENTITY FULL</literal> and many <command>UPDATE</command> and <command>DELETE</command> statements are |