今天我升级了 Ubuntu 服务器上的所有软件：
sudo aptitude upgrade
升级效果不佳，postgresql 没有启动，出现错误：
alex@db:~$ sudo service postgresql start
* Starting PostgreSQL 9.5 database server[fail]
* The PostgreSQL server failed to start. Please check the log output:
2015-10-30 12:42:09 MSK FATAL: database files are incompatible with server
2015-10-30 12:42:09 MSK DETAIL: The database cluster was initialized with CATALOG_VERSION_NO 201507281, but the server was compiled with CATALOG_VERSION_NO 201510051.
2015-10-30 12:42:09 MSK HINT: It looks like you need to initdb.
我不记得升级前服务器上是哪个版本的 postgresql，但升级后我只看到一个数据目录和一个集群：
alex@db:~$ ls /var/lib/postgresql/
9.5 Maildir
alex@db:~$ pg_lsclusters
Ver Cluster Port Status Owner Data directory Log file
9.5 main 5432 down postgres /var/lib/postgresql/9.5/main /var/log/postgresql/postgresql-9.5-main.log
所以看起来这是一个小升级。
在某处复制数据目录后，运行initdb，aptitude upgrade我再次注意到创建了一个 9.4 集群：
alex@db:~$ sudo cp /var/lib/postgresql/9.5/main /var/lib/postgresql/9.5/main.old
alex@db:~$ sudo /usr/lib/postgresql/9.5/bin/initdb -D /var/lib/postgresql/9.5/main/
alex@db:~$ sudo aptitude upgrade
alex@db:~$ ls /var/lib/postgresql/
9.4 9.5 Maildir
alex@db:~$ pg_lsclusters
Ver Cluster Port Status Owner Data directory Log file
9.4 main 5433 down postgres /var/lib/postgresql/9.4/main /var/log/postgresql/postgresql-9.4-main.log
9.5 main 5432 down postgres /var/lib/postgresql/9.5/main /var/log/postgresql/postgresql-9.5-main.log
现在它工作正常，但是如何从 /var/lib/postgresql/9.5/main.old 恢复保存的数据？pg_upgrade 不起作用。而且...是的，我在升级之前没有创建备份。
更新：
内容/etc/apt/sources.list
#######################################################################################
# Hetzner APT-Mirror
#
deb http://mirror.hetzner.de/ubuntu/packages trusty main restricted universe multiverse
deb http://mirror.hetzner.de/ubuntu/packages trusty-backports main restricted universe multiverse
deb http://mirror.hetzner.de/ubuntu/packages trusty-updates main restricted universe multiverse
deb http://mirror.hetzner.de/ubuntu/security trusty-security main restricted universe multiverse
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://de.archive.ubuntu.com/ubuntu/ trusty main restricted
deb-src http://de.archive.ubuntu.com/ubuntu/ trusty main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://de.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb-src http://de.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://de.archive.ubuntu.com/ubuntu/ trusty universe
deb-src http://de.archive.ubuntu.com/ubuntu/ trusty universe
deb http://de.archive.ubuntu.com/ubuntu/ trusty-updates universe
deb-src http://de.archive.ubuntu.com/ubuntu/ trusty-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://de.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://de.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://de.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb-src http://de.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://de.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://de.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu trusty-security main restricted
deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted
deb http://security.ubuntu.com/ubuntu trusty-security universe
deb-src http://security.ubuntu.com/ubuntu trusty-security universe
deb http://security.ubuntu.com/ubuntu trusty-security multiverse
deb-src http://security.ubuntu.com/ubuntu trusty-security multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu trusty partner
# deb-src http://archive.canonical.com/ubuntu trusty partner
## Uncomment the following two lines to add software from Ubuntu's
## 'extras' repository.
## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
# deb http://extras.ubuntu.com/ubuntu trusty main
# deb-src http://extras.ubuntu.com/ubuntu trusty main
deb http://packages.elasticsearch.org/elasticsearch/1.4/debian stable main
更新2：
alex@db:~$ sudo dpkg -l postgresql\*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-=========================================================-=================================-=================================-=======================================================================================================================
ii postgresql 9.4+170.pgdg14.04+1 all object-relational SQL database (supported version)
un postgresql-7.4 <none> <none> (no description available)
un postgresql-8.0 <none> <none> (no description available)
un postgresql-9.1 <none> <none> (no description available)
ii postgresql-9.3 9.3.10-1.pgdg14.04+1 amd64 object-relational SQL database, version 9.3 server
ii postgresql-9.4 9.4.5-1.pgdg14.04+1 amd64 object-relational SQL database, version 9.4 server
ii postgresql-9.5 9.5~beta1-1.pgdg14.04+1 amd64 object-relational SQL database, version 9.5 server
un postgresql-client <none> <none> (no description available)
ii postgresql-client-9.3 9.3.10-1.pgdg14.04+1 amd64 front-end programs for PostgreSQL 9.3
ii postgresql-client-9.4 9.4.5-1.pgdg14.04+1 amd64 front-end programs for PostgreSQL 9.4
ii postgresql-client-9.5 9.5~beta1-1.pgdg14.04+1 amd64 front-end programs for PostgreSQL 9.5
ii postgresql-client-common 170.pgdg14.04+1 all manager for multiple PostgreSQL client versions
ii postgresql-common 170.pgdg14.04+1 all PostgreSQL database-cluster manager
ii postgresql-contrib 9.4+170.pgdg14.04+1 all additional facilities for PostgreSQL (supported version)
ii postgresql-contrib-9.3 9.3.10-1.pgdg14.04+1 amd64 additional facilities for PostgreSQL
ii postgresql-contrib-9.4 9.4.5-1.pgdg14.04+1 amd64 additional facilities for PostgreSQL
ii postgresql-contrib-9.5 9.5~beta1-1.pgdg14.04+1 amd64 additional facilities for PostgreSQL
ii postgresql-doc 9.4+170.pgdg14.04+1 all documentation for the PostgreSQL database management system
ii postgresql-doc-9.3 9.3.10-1.pgdg14.04+1 all documentation for the PostgreSQL database management system
ii postgresql-doc-9.4 9.4.5-1.pgdg14.04+1 all documentation for the PostgreSQL database management system
un postgresql-doc-9.5 <none> <none> (no description available)
ii postgresql-server-dev-9.3 9.3.10-1.pgdg14.04+1 amd64 development files for PostgreSQL 9.3 server-side programming
alex@db:~$ sudo apt-cache policy postgresql-9.5
postgresql-9.5:
Installed: 9.5~beta1-1.pgdg14.04+1
Candidate: 9.5~beta1-1.pgdg14.04+1
Version table:
*** 9.5~beta1-1.pgdg14.04+1 0
500 http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg/main amd64 Packages
100 /var/lib/dpkg/status