使用pg_basebackup搭建PostgreSQL流複製環境 原

環境：
    OS:

[ha@node0 ~]$ uname -a
Linux node0 2.6.32-358.el6.x86_64 #1 SMP Fri Feb 22 00:31:26 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

    內存：1G
    CPU：1核
    數據庫:

postgres=# select version();
                                                    version                     
                               
--------------------------------------------------------------------------------
-------------------------------
 PostgreSQL 9.4.5 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.4.7 20120
313 (Red Hat 4.4.7-16), 64-bit
(1 row)

postgres=#

    .bash_profile

[ha@node0 ~]$ cat .bash_profile 
# .bash_profile

# Get the aliases and functions
if [ -f ~/.bashrc ]; then
	. ~/.bashrc
fi

# User specific environment and startup programs

export PGHOME=/home/ha/pgdb/
export PGDATA=/home/ha/pgdb/data/
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$PGHOME/lib/
export PATH=$PGHOME/bin:$PATH:$HOME/bin

    搭建過程：
    1.主庫配置
        a.postgresql.conf：

listen_addresses = '*'
wal_level = hot_standby
archive_mode = off
max_wal_senders = 3
wal_keep_segments = 16

        這裏要說明的是參數archive_mode，我在實驗過程中有一次發現參數archive_mode和archive_command在不設置的情況下也可以完成流複製，所以我對此進行了調研，發現francs已經對此進行了解釋，這裏引用francs的結論：

在搭建流複製環境時，並不必須設置 archive_mode 參數爲 on ，很多資料在介紹搭建流複製環境時設置這個參數爲 on ，可能是出於開啓 WAL 歸檔更安全的原因，因爲在主庫宕機並且較長時間不能恢復時，從庫依然可以讀取歸檔目錄的 WAL，從而保證不丟數據; 另一方面，如果主庫設置了較大的 wal_keep_segments ，也可以不用開啓archive_mode，因爲主庫保留了足夠的 WAL，從而大大降低了因從庫所需要的 WAL 被主庫覆蓋而需要從歸檔去取 WAL 的情況。所以從這方面說，archive_mode 參數的設置與搭建流複製並沒有直接關係。 提示： 對於比較繁忙的庫，在搭建流複製從庫時，建議主庫設置較大的 wal_keep_segments 參數。

        b.pg_hba.conf

host    all             all             192.168.238.0/24        md5
host    replication     rep             192.168.238.0/24        trust

        這裏說明的是，網上有其他對replication設置爲md5，並建立.pgpass文件，這種方法也是可行的。

        c.新建用戶rep

create user rep replication encrypted password 'rep';

    2.使用pg_basebackup進行從庫備份

[ha@localhost pgdb]$ pg_basebackup -D $PGDATA -F p -X stream -v -P -h 192.168.238.130 -U rep
transaction log start point: 0/2000028 on timeline 1
pg_basebackup: starting background WAL receiver
20945/20945 kB (100%), 1/1 tablespace                                         
transaction log end point: 0/20000F0
pg_basebackup: waiting for background process to finish streaming ...
pg_basebackup: base backup completed
[ha@localhost pgdb]$ ll
total 20
drwxrwxr-x.  2 ha ha 4096 Dec 26 00:54 bin
drwx------. 18 ha ha 4096 Dec 26 12:02 data
drwxrwxr-x.  4 ha ha 4096 Dec 26 00:54 include
drwxrwxr-x.  4 ha ha 4096 Dec 26 00:54 lib
drwxrwxr-x.  4 ha ha 4096 Dec 26 00:54 share
[ha@localhost pgdb]$ cd data/
[ha@localhost data]$ ls
backup_label  pg_hba.conf    pg_replslot   pg_subtrans  postgresql.auto.conf
base          pg_ident.conf  pg_serial     pg_tblspc    postgresql.conf
global        pg_logical     pg_snapshots  pg_twophase
pg_clog       pg_multixact   pg_stat       PG_VERSION
pg_dynshmem   pg_notify      pg_stat_tmp   pg_xlog

    這裏需要對目錄進行一下說明：data目錄可以通過pg_basebackup自動創建，但是其他表空間，需要手動創建並賦權，這裏需要注意的是，權限爲700。

    3.從庫配置
        a.postgresql.conf

hot_standby = on

        b.recovery.conf

standby_mode = on
primary_conninfo = 'host=192.168.238.130 port=5432 user=rep'
trigger_file = '/home/ha/pgdb/pg.trigger.file'

    4.備庫啓動前，主庫進程

[ha@localhost pgdb]$ ps -ef | grep post
root       2124      1  0 04:47 ?        00:00:00 /usr/libexec/postfix/master
postfix    2147   2124  0 04:47 ?        00:00:00 qmgr -l -t fifo -u
postfix   10385   2124  0 11:27 ?        00:00:00 pickup -l -t fifo -u
ha        10691      1  0 12:33 pts/3    00:00:00 /home/ha/pgdb/bin/postgres_ora
ha        10693  10691  0 12:33 ?        00:00:00 postgres: checkpointer process   
ha        10694  10691  0 12:33 ?        00:00:00 postgres: writer process      
ha        10695  10691  0 12:33 ?        00:00:00 postgres: wal writer process   
ha        10696  10691  0 12:33 ?        00:00:00 postgres: autovacuum launcher process   
ha        10697  10691  0 12:33 ?        00:00:00 postgres: stats collector process   
ha        10717   4087  0 12:37 pts/3    00:00:00 grep post

    5.備庫啓動後
        a.主庫進程

[ha@localhost pgdb]$ ps -ef | grep post
root       2124      1  0 04:47 ?        00:00:00 /usr/libexec/postfix/master
postfix    2147   2124  0 04:47 ?        00:00:00 qmgr -l -t fifo -u
postfix   10385   2124  0 11:27 ?        00:00:00 pickup -l -t fifo -u
ha        10691      1  0 12:33 pts/3    00:00:00 /home/ha/pgdb/bin/postgres_ora
ha        10693  10691  0 12:33 ?        00:00:00 postgres: checkpointer process   
ha        10694  10691  0 12:33 ?        00:00:00 postgres: writer process      
ha        10695  10691  0 12:33 ?        00:00:00 postgres: wal writer process   
ha        10696  10691  0 12:33 ?        00:00:00 postgres: autovacuum launcher process   
ha        10697  10691  0 12:33 ?        00:00:00 postgres: stats collector process   
ha        10718  10691  0 12:37 ?        00:00:00 postgres: wal sender process rep 192.168.238.131(59195) streaming 0/3000060
ha        10720   4087  0 12:37 pts/3    00:00:00 grep post

        b.備庫進程

[ha@localhost data]$ ps -ef | grep post
root       2086      1  0 04:48 ?        00:00:00 /usr/libexec/postfix/master
postfix    2108   2086  0 04:48 ?        00:00:00 qmgr -l -t fifo -u
postfix    9657   2086  0 11:27 ?        00:00:00 pickup -l -t fifo -u
ha         9782      1  0 12:36 pts/2    00:00:00 /home/ha/pgdb/bin/postgres
ha         9783   9782  0 12:36 ?        00:00:00 postgres: startup process   recovering 000000010000000000000003
ha         9784   9782  0 12:36 ?        00:00:00 postgres: checkpointer process   
ha         9785   9782  0 12:36 ?        00:00:00 postgres: writer process   
ha         9786   9782  0 12:36 ?        00:00:00 postgres: stats collector process   
ha         9787   9782  0 12:36 ?        00:00:00 postgres: wal receiver process   streaming 0/3000060
ha         9792   3744  0 12:37 pts/2    00:00:00 grep post

    6.實驗效果
        a.主庫

[ha@localhost pgdb]$ psql postgres
psql (9.4.5)
Type "help" for help.

postgres=# create table test(id int);
CREATE TABLE
postgres=# insert into test values (1),(2);
INSERT 0 2
postgres=# select * from test ;
 id 
----
  1
  2
(2 rows)

postgres=#

        b.備庫

[ha@localhost data]$ psql postgres
psql (9.4.5)
Type "help" for help.

postgres=# select * from test ;
 id 
----
  1
  2
(2 rows)