Wiki / Configuration Parameters

wal_level determines how much information is written to the WAL. The default value is replica, which writes enough data to support WAL archiving and replication, including running read-only queries on a standby server. minimal removes all logging except the information required to recover from a crash or immediate shutdown. Finally, logical adds information necessary to support logical decoding. Each level includes the information logged at all lower levels. This parameter can only be set at server start. 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 Section 14.4.7). Operations that initiate this optimization include: ALTER ... SET TABLESPACE CLUSTER CREATE TABLE REFRESH MATERIALIZED VIEW (without CONCURRENTLY) REINDEX TRUNCATE However, minimal WAL does not contain sufficient information for point-in-time recovery, so replica or higher must be used to enable continuous archiving (archive_mode) 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 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 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 executed. In releases prior to 9.6, this parameter also allowed the values archive and hot_standby. These are still accepted but mapped to replica.

English manual coverage begins with PostgreSQL 7.4. Source history and runtime observations have their own recorded version boundaries.

boot val

replica

category

Write-Ahead Log / Settings

context

postmaster

documented

true

enumvals

minimal, replica, logical

extra desc

Unknown

lang

en

max val

Unknown

metadata version

18

min val

Unknown

name

wal_level

short desc

Sets the level of information written to the WAL.

source

pg-settings-source-snapshot

unit

Unknown

vartype

enum