第一种方法， pg_dumpall方法

pg_dumpall 可以转储一个数据库集群里的所有数据库到一个脚本文件。该脚本文件包含可以用于作为 psql 输入的 SQL 命令，从而恢复数据库。

先下载并安装高版本数据库（下载高版本PG数据库的RPM包即可，在此忽略）

第一步：在新目录中初始化新版本集群，并更改端口号为目标端口号

mkdir -p /dbdir/postgresql/5433/data

/usr/pgsql-10/bin/initdb -D /dbdir/postgresql/5433/data/

vi /dbdir/postgresql/5433/data/postgresql.conf

port=5433

listen_addresses='*'

max_connections=1000 –合适的值

wal_level=logical –逻辑**

cat postgresql.conf |grep port

cat postgresql.conf |grep listen

第二步：切换到新集群目录，拷贝白名单文件

cd /dbdir/postgresql/5433/data

cp /dbdir/postgresql/5432/data/pg_hba.conf .

5432指的是老版本目录

第三步： 更改旧实例的default_transaction_read_only参数，防止老环境写入新数据

show default_transaction_read_only ;

alter system set default_transaction_read_only =on ;

select pg_reload_conf();

show default_transaction_read_only ;

第四步：pg_dumpall 旧实例上所有的库表和全局信息,最好先提前评估一下数据量，否则耗时较长

pg_dumpall -h /tmp/ -p 5432 -f 5432.dat

第五步：关闭旧实例，启动新版本集群后

/usr/pgsql-9.4/bin/pg_ctl -D /dbdir/postgresql/5432/data/ stop -m fast

/usr/pgsql-10/bin/pg_ctl -D /dbdir/postgresql/5433/data/ start

psql -h /tmp/ -p 5433 -f 5432.dat

第六步：备份旧实例data目录文件为一个zip包，删掉data目录，防止不小心启动该旧实例

zip -r data.zip data

rm -rf data

第二种方法，pg_upgrade方法

pg_upgrade允许存储在PostgreSQL数据文件中的数据升级到更高的PostgreSQL主版本，而不需要进行主版本升级所需的数据的dump/restore。

第一步：在新目录中初始化升级集群

/dbdir/postgresql/5433/data

/usr/pgsql-10/bin/initdb -D /dbdir/postgresql/5433/data/

第二步：切换到新集群目录，拷贝白名单文件

cd /dbdir/postgresql/5433/data

cp /dbdir/postgresql/5432/data/pg_hba.conf .

5432指的是老版本目录

第三步：使用pg_upgrade 进行升级检查,安装了插件的话升级的话可能会遇到一些问题

$ /usr/pgsql-10/bin/pg_upgrade -b /usr/pgsql-9.4/bin -B /usr/pgsql-10/bin -d /dbdir/postgresql/5432/data -D /dbdir/postgresql/5433/data -k -c

Performing Consistency Checks on Old Live Server

————————————————

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* data types in user tables ok

Checking for contrib/isn with bigint-passing miatch ok

Checking for invalid "unknown" user columns ok

Checking for hash indexes ok

Checking for roles starting with "pg_" ok

Checking for presence of required libraries ok

Checking database user is the install user ok

Checking for prepared transactions ok

*Clusters are compatible*

$ /usr/pgsql-10/bin/pg_upgrade -b /usr/pgsql-9.4/bin -B /usr/pgsql-10/bin -d /dbdir/postgresql/5432/data -D /dbdir/postgresql/5433/data

There seems to be a postmaster servicing the old cluster.

Please shutdown that postmaster and try again.

Failure, exiting

安装插件后可能会遇到下面问题：

could not load library "$libdir/postgis-2.2": ERROR: could not access file "$libdir/postgis-2.2": No such file or directory

could not load library "$libdir/rtpostgis-2.2": ERROR: could not access file "$libdir/rtpostgis-2.2": No such file or directory

could not load library "$libdir/postgis_topology-2.2": ERROR: could not access file "$libdir/postgis_topology-2.2": No such file or directory

第四步：存在插件的可以先删除不必要的插件，升级检查通过后，关闭实例

$ /usr/pgsql-9.4/bin/pg_ctl -D /dbdir/postgresql/5432/data/ stop -m fast

waiting for server to shut down…. done

server stopped

第五步：pg_upgrade升级集群到新目录

$ /usr/pgsql-10/bin/pg_upgrade -b /usr/pgsql-9.4/bin -B /usr/pgsql-10/bin -d /dbdir/postgresql/5432/data -D /dbdir/postgresql/5433/data

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* data types in user tables ok

Checking for contrib/isn with bigint-passing miatch ok

Checking for invalid "unknown" user columns ok

Checking for roles starting with "pg_" 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 in the new cluster ok

Deleting files from new pg_xact 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

Copying user relation files

ok

Setting next OID for new cluster ok

Sync data directory to disk ok

Creating script to *yze new cluster ok

Creating script to delete old cluster ok

Checking for hash indexes ok

Upgrade Complete

—————-

Optimizer statistics are not transferred by pg_upgrade so,

once you start the new server, consider running:

./*yze_new_cluster.sh

Running this script will delete the old cluster's data files:

./delete_old_cluster.sh

第六步：启动实例，也可以做一些*yze等维护操作。

/usr/pgsql-10/bin/pg_ctl -D /dbdir/postgresql/5433/data start