PG数据库升级步骤说明（pg_dumpall和pg_upgrade）

一、数据库升级9.4到9.5

1.pg_dump导入导出（数据量不大时使用）
postgres用户登录
$ pg_dumpall > db_export.out

$ env|grep LANG
LANG=en_US.UTF-8

如果数据库字符集为en_US.UTF-8，系统字符集为zh_CN.UTF-8

导入步骤为
postgres用户登录
$export LANG=en_US.UTF-8
$psql -f db_export.out postgres

2.pg_upgrade(pg_upgrade方式)
升级版本：9.4 --》9.5
升级前提：9.4数据库中有完整数据，9.5安装完成后仅需要initdb就可以

1)升级前一致性检查

postgres用户登录执行以下命令：
[root@pgdb01 pgdata]# su - postgres
[postgres@pgdb01 ~]$ pwd
/home/postgres

使用9.5新版本bin路径的pg_upgrade执行检查。

[postgres@pgdb01 ~]$ /opt/pg/9.5/bin/pg_upgrade -c -d /pgdata94 -D /pgdata -b /opt/pg/9.4/bin -B /opt/pg/9.5/bin
Performing Consistency Checks
-----------------------------
Checking cluster versions ok
Checking database user is the install user ok
Checking database connection settings ok
Checking for prepared transactions ok
Checking for reg* system OID user data types ok
Checking for contrib/isn with bigint-passing mismatch ok
Checking for presence of required libraries ok
Checking database user is the install user ok
Checking for prepared transactions ok

*Clusters are compatible*
[postgres@pgdb01 ~]$

2).执行升级

升级方式：复制数据文件方式，9.4旧版本PGDATA中数据复制到9.5新版本PGDATA，执行速度慢，两个数据目录独立，保存双份数据；
硬链接方式，升级时命令行加上--link参数，不复制数据仅建立连接，执行速度快，仅保存一份数据。

（注意：两个数据库执行这个步骤时，全部为停止状态）

[postgres@pgdb01 ~]$ /opt/pg/9.5/bin/pg_upgrade -d /pgdata94 -D /pgdata -b /opt/pg/9.4/bin -B /opt/pg/9.5/bin
Performing Consistency Checks
-----------------------------
Checking cluster versions ok
Checking database user is the install user ok
Checking database connection settings ok
Checking for prepared transactions ok
Checking for reg* system OID user data types ok
Checking for contrib/isn with bigint-passing mismatch ok
Creating dump of global objects ok
Creating dump of database schemas
ok
Checking for presence of required libraries ok
Checking database user is the install user ok
Checking for prepared transactions ok

If pg_upgrade fails after this point, you must re-initdb the
new cluster before continuing.

Performing Upgrade
------------------
Analyzing all rows in the new cluster ok
Freezing all rows on the new cluster ok
Deleting files from new pg_clog ok
Copying old pg_clog to new server ok
Setting next transaction ID and epoch for new cluster ok
Deleting files from new pg_multixact/offsets ok
Copying old pg_multixact/offsets to new server ok
Deleting files from new pg_multixact/members ok
Copying old pg_multixact/members to new server ok
Setting next multixact ID and offset for new cluster ok
Resetting WAL archives ok
Setting frozenxid and minmxid counters in new cluster ok
Restoring global objects in the new cluster ok
Restoring database schemas in the new cluster
ok
Creating newly-required TOAST tables ok
Copying user relation files
ok
Setting next OID for new cluster ok
Sync data directory to disk ok
Creating script to analyze new cluster ok
Creating script to delete old cluster ok

Upgrade Complete
----------------
Optimizer statistics are not transferred by pg_upgrade so,
once you start the new server, consider running:
./analyze_new_cluster.sh

Running this script will delete the old cluster's data files:
./delete_old_cluster.sh
[postgres@pgdb01 ~]$

[postgres@pgdb01 ~]$ ll
total 1208
-rwx------. 1 postgres postgres 749 Apr 9 18:52 analyze_new_cluster.sh
-rwx------. 1 postgres postgres 30 Apr 9 18:52 delete_old_cluster.sh
[postgres@pgdb01 ~]$

3).使用新版本启动脚本启动数据库

[postgres@pgdb01 ~]$ exit
logout
[root@pgdb01 pgdata]# /etc/init.d/postgresql start
Starting PostgreSQL: ok
[root@pgdb01 pgdata]# su - postgres
[postgres@pgdb01 ~]$ psql
psql (9.5.2)
Type "help" for help.

postgres=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
--------------------+----------+----------+-------------+-------------+-----------------------
a_authentication | vincent | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
a_resources | vincent | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
a_server | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | postgres=CTc/postgres+
| | | | | =Tc/postgres +
| | | | | acent=CTc/postgres
template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | postgres=CTc/postgres+
| | | | | =c/postgres
a_security | uccc | UTF8 | en_US.UTF-8 | en_US.UTF-8 | a=CTc/uccc +
| | | | | =Tc/uccc +
| | | | | a=CTc/uccc
(7 rows)

postgres=# \q

4).生产新的统计数据

[postgres@pgdb01 ~]$ ./analyze_new_cluster.sh
This script will generate minimal optimizer statistics rapidly
so your system is usable, and then gather statistics twice more
with increasing accuracy. When it is done, your system will
have the default level of optimizer statistics.

If you have used ALTER TABLE to modify the statistics target for
any tables, you might want to remove them and restore them after
running this script because they will delay fast statistics generation.

If you would like default statistics as quickly as possible, cancel
this script and run:
"/opt/pg/9.5/bin/vacuumdb" --all --analyze-only

vacuumdb: processing database "a_authentication": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "a_resources": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "postgres": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "a_server": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "template1": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "a_security": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "a_authentication": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "a_resources": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "postgres": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "a_server": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "template1": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "a_security": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "a_authentication": Generating default (full) optimizer statistics
vacuumdb: processing database "a_resources": Generating default (full) optimizer statistics
vacuumdb: processing database "postgres": Generating default (full) optimizer statistics
vacuumdb: processing database "a_server": Generating default (full) optimizer statistics
vacuumdb: processing database "template1": Generating default (full) optimizer statistics
vacuumdb: processing database "a_security": Generating default (full) optimizer statistics

Done
[postgres@pgdb01 ~]$

5).旧版本数据清理

可以在新数据库运行一段时间后，执行delete_old_cluster.sh 脚本，删除旧版本PGDATA目录
[postgres@pgdb01 ~]$ more delete_old_cluster.sh
#!/bin/sh

rm -rf '/pgdata94'
[postgres@pgdb01 ~]$