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---
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title: "[筆記] 用pbackrest 備份還原 postgresql / Backup Restore Postgresql With Pgbackrest"
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date: 2019-09-05T11:42:28+08:00
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noSummary: false
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image: "https://h.cowbay.org/images/post-default-15.jpg"
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categories: ['筆記']
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tags: ['postgresql']
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author: "Eric Chang"
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keywords:
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- postgresql
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- pgbackrest
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---
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這兩天在測試pgbackrest ，簡單筆記一下測試狀況
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<!--more-->
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#### install
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在ubuntu 18.04 安裝pgbackrest 很簡單，內建在apt裡面，所以可以直接用
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```
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sudo apt install pgbackrest
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```
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進行安裝
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#### config
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pgbackrest 的設定檔在 /etc/pgbackrest/pgbackrest.conf
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如果是用apt 安裝，預設會建立一個 /etc/pgbackrest.conf
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但是這個路徑是錯誤的
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執行 pgbackrest的時候，預設還是會去讀取 /etc/pgbackrest/pgbackrest.conf
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要特別注意，要不就是每次都指定config路徑，要不就是把那個錯誤的設定檔幹掉
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#### config 內容
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內容其實很簡單
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```
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postgres@hqdc039:~$ cat /etc/pgbackrest/pgbackrest.conf
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[demo]
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pg1-path=/database/11/main
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[global]
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repo1-cipher-pass=zWaf6XtpjIVZC5444yXB+cgFDFl7MxGlgkZSaoPvTGirhPygu4jOKOXf9LO4vjfO
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repo1-cipher-type=aes-256-cbc
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repo1-path=/var/lib/pgbackrest
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repo1-retention-full=2
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[global:archive-push]
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compress-level=3
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process-max=4
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```
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**[demo]** 用來指定這個 "stanza" 的名稱
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* pg1-path 是資料庫存放的路徑
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**[global]** 中的兩個cipher 用途我不清楚，不設定也沒關係
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* "repo1-path" 則是用來存放備份的路徑
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* "repo1-retention-full" 定義要保留幾次 full backup
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**[global:archive-push]** 似乎是用來定義在備份/還原時的選項
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* process-max 指定要用多少process (平行處理)
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#### 簡單流程
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* config (pgbackrest & postgresql )
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* 建立 stanza
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* 建立備份
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* (還原，如果有需要的話)
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#### 其他部份
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* 清除 stanza (刪除備份)
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* 踩到的地雷
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***
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#### 設定 pgbackrest & postgresql
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pgbackrest 基本上設定很簡單，內容就跟上面的一樣就可以跑了。
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當然要新增其他進階的，就要自己研究了，內容有夠長
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https://pgbackrest.org/configuration.html
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在postgresql 中，要新增一些設定，主要是 archive_command
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```
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postgres@hqdc039:~$ grep -A 100 "for pgbackrest" /etc/postgresql/11/main/postgresql.conf
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#for pgbackrest
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archive_command = 'pgbackrest --stanza=demo archive-push %p'
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archive_mode = on
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listen_addresses = '*'
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log_line_prefix = ''
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max_wal_senders = 3
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wal_level = replica
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postgres@hqdc039:~$
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```
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**archive_command**
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這個因為要帶stanza 名稱進來，所以**需要跟pgbackrest.conf 裡面定義的名稱一致**
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**max_wal_senders**
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簡單說就是定義在抄寫wal 的時候，可以同時抄給幾台
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這是postgresql 的說明
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```
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the maximum number of simultaneously running WAL sender processes
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```
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**wal_level**
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有三種等級，參考 https://blog.csdn.net/pg_hgdb/article/details/78666719
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* minimal --不能通过基础备份和wal日志恢复数据库。
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* replica = 9.6版本以前的archive和hot_standby --该级别支持wal归档和复制。
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* logical --在replica级别的基础上添加了支持逻辑解码所需的信息。
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設定完成後，重起 postgresql 就可以了
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#### 建立 stanza
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stanza 這名詞我是第一次聽到，直接翻譯就是 **""（詩的）節，段"**
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https://dictionary.cambridge.org/zht/%E8%A9%9E%E5%85%B8/%E8%8B%B1%E8%AA%9E-%E6%BC%A2%E8%AA%9E-%E7%B9%81%E9%AB%94/stanza
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在pgbackrest中，可以一次定義多個 stanza，用來備份不同的DB
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這次環境很簡單，所以就只有設定一個
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依照上面的pgbackrest.conf 內容設定好了，需要先建立這個stanza
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指令:
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```
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postgres@hqdc039:~$ pgbackrest --stanza=demo stanza-create --log-level-console=detail
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2019-09-04 16:21:40.700 P00 INFO: stanza-create command begin 2.16: --log-level-console=detail --pg1-path=/database/11/main --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --stanza=demo
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2019-09-04 16:21:41.525 P00 INFO: stanza-create command end: completed successfully (825ms)
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postgres@hqdc039:~$
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```
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接著就可以執行備份了
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#### backup
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備份指令也很簡單，要注意的是，如果不帶參數，pgbackrest 會自行決定要用incremental或者是 full backup
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```
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postgres@hqdc039:~$ pgbackrest --stanza=demo --log-level-console=detail backup
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2019-09-04 16:41:17.458 P00 INFO: backup command begin 2.16: --log-level-console=detail --pg1-path=/database/11/main --repo1-cipher-pass=<redacted> --repo1-cipher-type=aes-256-cbc --repo1-path=/var/lib/pgbackrest --repo1-retention-full=2 --stanza=demo
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2019-09-04 16:41:17.697 P00 INFO: last backup label = 20190904-134245F, version = 2.16
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2019-09-04 16:41:18.607 P00 INFO: execute non-exclusive pg_start_backup() with label "pgBackRest backup started at 2019-09-04 16:41:17": backup begins after the next regular checkpoint completes
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2019-09-04 16:41:19.008 P00 INFO: backup start archive = 000000100000000E0000004A, lsn = E/4A000028
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WARN: a timeline switch has occurred since the last backup, enabling delta checksum
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2019-09-04 16:41:21.213 P01 DETAIL: match file from prior backup /database/11/main/base/51435/51488 (546.3MB, 20%) checksum 5eb4f73d9b1c535ebfdfb622d930dade87e23786
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2019-09-04 16:41:21.821 P01 DETAIL: match file from prior backup /database/11/main/base/51435/51460 (455.3MB, 37%) checksum aa74bba2bea8823789ad4194e4574b44a020271a
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...
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...
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...
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2019-09-04 16:41:24.827 P01 DETAIL: match file from prior backup /database/11/main/PG_VERSION (3B, 100%) checksum dd71038f3463f511ee7403dbcbc87195302d891c
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2019-09-04 16:41:24.835 P01 INFO: backup file /database/11/main/base/13125/51569 (0B, 100%)
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2019-09-04 16:41:24.860 P00 INFO: incr backup size = 2.5GB
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2019-09-04 16:41:24.860 P00 INFO: execute non-exclusive pg_stop_backup() and wait for all WAL segments to archive
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2019-09-04 16:41:24.961 P00 INFO: backup stop archive = 000000100000000E0000004A, lsn = E/4A000130
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2019-09-04 16:41:24.964 P00 DETAIL: wrote 'pg_data/backup_label' file returned from pg_stop_backup()
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2019-09-04 16:41:25.155 P00 INFO: new backup label = 20190904-134245F_20190904-164117I
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2019-09-04 16:41:25.194 P00 INFO: backup command end: completed successfully (7736ms)
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2019-09-04 16:41:25.194 P00 INFO: expire command begin
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2019-09-04 16:41:25.214 P00 INFO: full backup total < 2 - using oldest full backup for 11-1 archive retention
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2019-09-04 16:41:25.214 P00 DETAIL: archive retention on backup 20190904-134245F, archiveId = 11-1, start = 0000000D0000000E00000048
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2019-09-04 16:41:25.215 P00 DETAIL: no archive to remove, archiveId = 11-1
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2019-09-04 16:41:25.215 P00 INFO: expire command end: completed successfully (21ms)
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postgres@hqdc039:~$
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```
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執行後，可以檢查一下
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```
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postgres@hqdc039:~$ pgbackrest --stanza=demo --log-level-console=info info
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stanza: demo
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status: ok
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cipher: aes-256-cbc
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db (current)
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wal archive min/max (11-1): 0000000D0000000E00000048/000000100000000E0000004A
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full backup: 20190904-134245F
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timestamp start/stop: 2019-09-04 13:42:45 / 2019-09-04 13:48:54
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wal start/stop: 0000000D0000000E00000048 / 0000000D0000000E00000048
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database size: 2.6GB, backup size: 2.6GB
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repository size: 547MB, repository backup size: 547MB
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incr backup: 20190904-134245F_20190904-164117I
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timestamp start/stop: 2019-09-04 16:41:17 / 2019-09-04 16:41:25
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wal start/stop: 000000100000000E0000004A / 000000100000000E0000004A
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database size: 2.6GB, backup size: 2.2MB
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repository size: 547MB, repository backup size: 220.4KB
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backup reference list: 20190904-134245F
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postgres@hqdc039:~$
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```
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#### 還原測試
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pgbackrest 的還原因為透過WAL ，所以有一些觀念需要先釐清
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本來我的測試是先做好備份，然後直接砍掉 DB，接著再用restore還原
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卻發現砍掉的DB居然沒有回來..
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後來看了這一篇，然後又研究了一下 **Point-in-Time Recovery**
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https://github.com/pgbackrest/pgbackrest/issues/800
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才找到正確的用法
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先把DB整個砍掉
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```
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postgres@hqdc034:/zp/database$ time dropdb demo
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```
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然後停止postgresql 服務
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```
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postgres@hqdc034:/zp/database$ pg_ctlcluster 10 main stop
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sudo systemctl stop postgresql@10-main
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```
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接著就可以來下指令還原了
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```
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postgres@hqdc034:/zp/database$ time pgbackrest --stanza=demo --log-level-console=info --delta --type=time "--target=2019-09-05 11:00:00.268248+08" --target-action=promote restore
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2019-09-05 11:15:57.480 P00 INFO: restore command begin 2.13: --delta --log-level-console=info --pg1-path=/zp/database/10/main --process-max=4 --repo1-path=/var/lib/pgbackrest --stanza=demo --target="2019-09-05 11:00:00.268248+08" --target-action=promote --type=time
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2019-09-05 11:15:57.624 P00 INFO: restore backup set 20190905-111109F
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2019-09-05 11:15:57.947 P00 INFO: remove invalid files/paths/links from /zp/database/10/main
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2019-09-05 11:16:00.440 P01 INFO: restore file /zp/database/10/main/global/pg_control.pgbackrest.tmp (8KB, 99%) checksum e253f9d706ac59e1ec0408ba477d1d5bac41b20f
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2019-09-05 11:16:00.791 P00 INFO: write /zp/database/10/main/recovery.conf
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2019-09-05 11:16:00.797 P00 INFO: restore global/pg_control (performed last to ensure aborted restores cannot be started)
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2019-09-05 11:16:00.800 P00 INFO: restore command end: completed successfully (3321ms)
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real 0m3.328s
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user 0m6.896s
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sys 0m0.832s
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```
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在DB目錄中，會產生一個recovery.conf，這是用來給 postgresql 看的檔案，裡面會紀錄怎麼還原、以及還原的類型、時間點，這邊指定要恢復到 ***2019-09-05 11:00:00.268248+08***
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這個時間格式要看資料庫的設定，可以藉由以下指令得到
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```
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postgres@hqdc034:/zp/database$ psql -Atc "select current_timestamp"
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2019-09-05 11:14:27.268248+08
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```
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檢查一下recovery.conf
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```
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postgres@hqdc034:/zp/database$ cat /zp/database/10/main/recovery.conf
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restore_command = 'pgbackrest --log-level-console=info --stanza=demo archive-get %f "%p"'
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recovery_target_time = '2019-09-05 11:00:00.268248+08'
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recovery_target_action = 'promote'
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```
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重新啟動postgresql 然後看看被砍掉的demo DB有沒有回來
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```
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postgres@hqdc034:/zp/database$ pg_ctlcluster 10 main start
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Warning: the cluster will not be running as a systemd service. Consider using systemctl:
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sudo systemctl start postgresql@10-main
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postgres@hqdc034:/zp/database$ psql
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psql (10.8 (Ubuntu 10.8-1.pgdg14.04+1))
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Type "help" for help.
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postgres=# \l
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List of databases
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Name | Owner | Encoding | Collate | Ctype | Access privileges
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-----------+----------+----------+-------------+-------------+-----------------------
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demo | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
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postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
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template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
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| | | | | postgres=CTc/postgres
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template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
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| | | | | postgres=CTc/postgres
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(4 rows)
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postgres=# \q
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postgres@hqdc034:/zp/database$
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```
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很好， demo DB 有順利的還原回來了，先暫時測試到這邊。接下來要來玩postgresql on zfs
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後續如果想更深入測試 pgbackrest，可以試試看異機備份還原。
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