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本篇內(nèi)容主要講解“怎么使用pg_rewind”，感興趣的朋友不妨來看看。本文介紹的方法操作簡(jiǎn)單快捷，實(shí)用性強(qiáng)。下面就讓小編來帶大家學(xué)習(xí)“怎么使用pg_rewind”吧!
pg_rewind
是postgresql主叢數(shù)據(jù)庫之同步數(shù)據(jù)目錄的工具。需要目標(biāo)服務(wù)器在postgresql.conf 中允許wal_log_hints，或者在 initdb初始化集群時(shí)允許 checksums ，full_page_writes也必須為on
pg_rewind只復(fù)制表數(shù)據(jù)文件中更改的塊;所有其他文件都被完整復(fù)制，包括配置文件。pg_rewind相對(duì)于使用pg_basebackup備份或rsync等工具的優(yōu)勢(shì)在于，pg_rewind不需要讀取數(shù)據(jù)庫中未更改的塊。這使得在數(shù)據(jù)庫很大且之間只有一小部分塊不同的情況下，速度會(huì)快得多。
pg_rewind [option...] { -D | --target-pgdata } directory { --source-pgdata=directory | --source-server=connstr
參數(shù)：
-D directory --target-pgdata=directory
此選項(xiàng)指定與源同步的目標(biāo)數(shù)據(jù)目錄。在運(yùn)行pg_rewind之前，必須干凈關(guān)閉目標(biāo)服務(wù)器
--source-pgdata=directory
指定要與之同步的源服務(wù)器的數(shù)據(jù)目錄的文件系統(tǒng)路徑。此選項(xiàng)要求干凈關(guān)閉源服務(wù)器
--source-server=connstr
指定要連接到源PostgreSQL服務(wù)器的libpq連接字符串。連接必須是具有超級(jí)用戶訪問權(quán)限的正常(非復(fù)制)連接。此選項(xiàng)要求源服務(wù)器正在運(yùn)行，而不是處于恢復(fù)模式。
-n --dry-run
除了實(shí)際修改目標(biāo)目錄之外，執(zhí)行所有操作。
-P --progress
使進(jìn)展報(bào)告。
實(shí)驗(yàn)使用兩臺(tái)主機(jī)，都安裝postgresql-10.7，已配置流復(fù)制
主：192.168.56.5 m1
叢：192.168.56.25 m7
m1(主)：創(chuàng)建測(cè)試表和數(shù)據(jù)
postgres=# create table test (id int,e_name varchar(100),e_mail varchar(100),d_id int); CREATE TABLE postgres=# \d List of relations Schema | Name | Type | Owner --------+------+-------+---------- public | test | table | postgres (1 row) postgres=# insert into test values(1,'zbs','[email protected]',10); INSERT 0 1 postgres=# select * from test; id | e_name | e_mail | d_id ----+--------+-------------+------ 1 | zbs | [email protected] | 10 (1 row)
m7 (叢)：查詢數(shù)據(jù)復(fù)制成功
[postgres@z_leader ~]$ psql postgres psql (10.7) Type "help" for help. postgres=# \d List of relations Schema | Name | Type | Owner --------+------+-------+---------- public | test | table | postgres (1 row) postgres=# select * from test; id | e_name | e_mail | d_id ----+--------+-------------+------ 1 | zbs | [email protected] | 10 (1 row)
提升叢庫為新主庫
[postgres@z_leader data]$ pg_ctl promote -D /usr/local/pg/data waiting for server to promote.... done server promoted [postgres@z_leader data]$ psql postgres psql (10.7) Type "help" for help. postgres=# select pg_is_in_recovery(); pg_is_in_recovery ------------------- f (1 row)
m1(原主庫)插入一條記錄，模擬原主庫上的數(shù)據(jù)沒有復(fù)制到原叢庫上
postgres=# insert into test values(2,'zbs1','[email protected]',10); INSERT 0 1 postgres=# select * from test; id | e_name | e_mail | d_id ----+--------+-------------+------ 1 | zbs | [email protected] | 10 2 | zbs1 | [email protected] | 10 (2 rows)
m7：在原叢庫上(已提升為主庫)插入一條記錄并查看結(jié)果
postgres=# insert into test values(3,'zbs2','[email protected]',10); INSERT 0 1 postgres=# select * from test; id | e_name | e_mail | d_id ----+--------+-------------+------ 1 | zbs | [email protected] | 10 3 | zbs2 | [email protected] | 10 (2 rows)
m1 將原主庫變?yōu)樾轮鲙斓膮矌?/p>
[postgres@localhost ~]$ kill -INT `head -1 /usr/local/pg/data/postmaster.pid`
--配置流復(fù)制文件和參數(shù)
[postgres@localhost data]$ mv recovery.done recovery.conf [postgres@localhost data]$ cat recovery.conf standby_mode = 'on' restore_command = 'cp /usr/local/pg/arch/%f' primary_conninfo = 'host=192.168.56.25 port=5432 user=rep' recovery_target_timeline = 'latest' [postgres@localhost data]$
--啟動(dòng)數(shù)據(jù)庫
[postgres@localhost ~]$ /usr/local/pg/bin/pg_ctl -D /usr/local/pg/data -l logfile start waiting for server to start.... done server started [postgres@localhost data]$ psql postgres psql (10.7) Type "help" for help. postgres=# select pg_is_in_recovery(); pg_is_in_recovery ------------------- t (1 row) postgres=# select * from test; id | e_name | e_mail | d_id ----+--------+-------------+------ 1 | zbs | [email protected] | 10 2 | zbs1 | [email protected] | 10 (2 rows)
--在m7上插入的記錄未能復(fù)制過來
---日志信息
2019-03-02 09:15:17.415 CST [2492] LOG: consistent recovery state reached at 0/D000098 2019-03-02 09:15:17.415 CST [2492] LOG: invalid record length at 0/D000098: wanted 24, got 0 2019-03-02 09:15:17.415 CST [2490] LOG: database system is ready to accept read only connections 2019-03-02 09:15:17.429 CST [2500] LOG: fetching timeline history file for timeline 6 from primary server 2019-03-02 09:15:17.460 CST [2500] FATAL: could not start WAL streaming: ERROR: requested starting point 0/D000000 on timeline 5 is not in this server's history DETAIL: This server's history forked from timeline 5 at 0/C003168. cp: missing destination file operand after `/usr/local/pg/arch/00000006.history' Try `cp --help' for more information. cp: missing destination file operand after `/usr/local/pg/arch/00000007.history' Try `cp --help' for more information. cp: missing destination file operand after `/usr/local/pg/arch/00000006.history' Try `cp --help' for more information. 2019-03-02 09:15:17.469 CST [2492] LOG: new timeline 6 forked off current database system timeline 5 before current recovery point 0/D000098 cp: missing destination file operand after `/usr/local/pg/arch/00000005000000000000000D
[postgres@localhost ~]$ kill -INT `head -1 /usr/local/pg/data/postmaster.pid`
---使得pg_rewind 同步數(shù)據(jù)庫時(shí)間線
[[postgres@localhost ~]$ pg_rewind --target-pgdata /usr/local/pg/data --source-server='host=192.168.56.25 port=5432 user=postgres dbname=postgres' -P connected to server servers diverged at WAL location 0/C003168 on timeline 5 rewinding from last common checkpoint at 0/C003010 on timeline 5 reading source file list reading target file list reading WAL in target need to copy 100 MB (total source directory size is 118 MB) 102599/102599 kB (100%) copied creating backup label and updating control file syncing target data directory Done!
--pg_rewind后此文件需要重新配置
[postgres@localhost data]$ cat recovery.conf standby_mode = 'on' restore_command = 'cp /usr/local/pg/arch/%f' primary_conninfo = 'host=192.168.56.25 port=5432 user=rep' recovery_target_timeline = 'latest'
[postgres@localhost ~]$ /usr/local/pg/bin/pg_ctl -D /usr/local/pg/data -l logfile start waiting for server to start.... done server started [postgres@localhost ~]$ psql postgres psql (10.7) Type "help" for help. postgres=# select * from test; id | e_name | e_mail | d_id ----+--------+-------------+------ 1 | zbs | [email protected] | 10 3 | zbs2 | [email protected] | 10 (2 rows) postgres=# select pg_is_in_recovery(); pg_is_in_recovery ------------------- t (1 row)
--原主庫沒有復(fù)制到叢庫的記錄消失，在新主庫上插入的記錄已同步
m7(新主庫) [postgres@z_leader ~]$ psql postgres psql (10.7) Type "help" for help. postgres=# insert into test values(4,'zbs2','[email protected]',10); INSERT 0 1 postgres=# select * from test; id | e_name | e_mail | d_id ----+--------+-------------+------ 1 | zbs | [email protected] | 10 3 | zbs2 | [email protected] | 10 4 | zbs2 | [email protected] | 10 (3 rows)
m1(新叢庫)
postgres=# select * from test; id | e_name | e_mail | d_id ----+--------+-------------+------ 1 | zbs | [email protected] | 10 3 | zbs2 | [email protected] | 10 4 | zbs2 | [email protected] | 10 (3 rows)
到此，相信大家對(duì)“怎么使用pg_rewind”有了更深的了解，不妨來實(shí)際操作一番吧！這里是創(chuàng)新互聯(lián)網(wǎng)站，更多相關(guān)內(nèi)容可以進(jìn)入相關(guān)頻道進(jìn)行查詢，關(guān)注我們，繼續(xù)學(xué)習(xí)！
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