PostgreSQL开启wal日志归档模式

1.检查归档模式是否开启

postgres=# show archive_mode;
 archive_mode 
--------------
 off
(1 row)

2.开启归档模式

## 创建归档目录
mkdir -p /pgsql15.4/pg_arch

## 配置归档相关参数
postgres=# alter system set archive_mode=on;
ALTER SYSTEM
postgres=# alter system set archive_command ='cp %p /pgsql15.4/pg_arch/%f';
ALTER SYSTEM

注意：%p：表示要归档的文件路径；%f：代表不包含路径信息的wal文件的文件名。

## 重启生效
pg_ctl restart

3.执行wal日志切换，检查是否生成归档

postgres=# select * from pg_ls_waldir() order by modification asc;
           name           |   size   |      modification      
--------------------------+----------+------------------------
 000000010000000000000001 | 16777216 | 2023-11-14 10:57:44+08
(1 row)

postgres=# checkpoint;
CHECKPOINT
postgres=# select pg_switch_wal();
 pg_switch_wal 
---------------
 0/1518E68
(1 row)

postgres=# select * from pg_ls_waldir() order by modification asc;
           name           |   size   |      modification      
--------------------------+----------+------------------------
 000000010000000000000003 | 16777216 | 2023-11-14 10:57:44+08
 000000010000000000000002 | 16777216 | 2023-11-14 11:02:41+08
(2 rows)

[postgres@pg pg_arch]$ ll
total 16384
-rw-------. 1 postgres postgres 16777216 Nov 14 10:57 000000010000000000000001

注意：开启归档后，会将 WAL 日志复制到归档目录，然后被清理掉。