PostgreSQL's latest major version is 12. That being said, it is fairly easy to migrate between versions even major ones. There are couple ways to upgrade, depending on how much you want to risk to compromise with. Practically there are 2 ways of Upgrade in any database:

• In-Place: You upgrade on the same host
• Out-Of-Place: You upgrade using 2nd host, most often via Replication or data migration directly to the new release.

We will discuss both methods in this section. So let's get started:

Important to note here is that even the In-place upgrade isn't so risky as with other databases (Oracle / SQL / DB2 and so on). The steps to perform In-Place upgrade in PostgreSQL between major version are pretty straight-forward. So let's get going: In this case, we will also, upgrade from 9.6 → 10.

You can install the new version by either compiling the source or using package manager (in my case yum).

[root@localhost 9.6]# yum install postgresql10-server.x86_64
Loaded plugins: fastestmirror, langpacks
Dependencies Resolved

=============================================================================================================================================================================================================================================================================
 Package                                                                 Arch                                                       Version                                                                 Repository                                                  Size
=============================================================================================================================================================================================================================================================================
Installing:
 postgresql10-server                                                     x86_64                                                     10.11-2PGDG.rhel7                                                       pgdg10                                                     4.5 M
Installing for dependencies:
 libicu                                                                  x86_64                                                     50.2-3.el7                                                              base                                                       6.9 M
 postgresql10                                                            x86_64                                                     10.11-2PGDG.rhel7                                                       pgdg10                                                     1.6 M
 postgresql10-libs                                                       x86_64                                                     10.11-2PGDG.rhel7                                                       pgdg10                                                     356 k

Transaction Summary
=============================================================================================================================================================================================================================================================================
Installed:
  postgresql10-server.x86_64 0:10.11-2PGDG.rhel7

Dependency Installed:
  libicu.x86_64 0:50.2-3.el7                                                     postgresql10.x86_64 0:10.11-2PGDG.rhel7                                                     postgresql10-libs.x86_64 0:10.11-2PGDG.rhel7

Complete!

The new version, will come in it's own binary and data locations:

/var/lib/pgsql/10/data
/usr/pgsql-10/bin

After that, we have to create a database base:

-bash-4.2$ /usr/pgsql-10/bin/initdb -D /var/lib/pgsql/10/data
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.

The database cluster will be initialized with locale "en_US.UTF-8".
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".

Data page checksums are disabled.

fixing permissions on existing directory /var/lib/pgsql/10/data ... ok
creating subdirectories ... ok
selecting default max_connections ... 100
selecting default shared_buffers ... 128MB
selecting default timezone ... America/New_York
selecting dynamic shared memory implementation ... posix
creating configuration files ... ok
running bootstrap script ... ok
performing post-bootstrap initialization ... ok
syncing data to disk ... ok

WARNING: enabling "trust" authentication for local connections
You can change this by editing pg_hba.conf or using the option -A, or
--auth-local and --auth-host, the next time you run initdb.

Success. You can now start the database server using:

    /usr/pgsql-10/bin/pg_ctl -D /var/lib/pgsql/10/data -l logfile start

-bash-4.2$

It is very good idea to check for possible compatability problems between the two versions in order to play it safe:

-bash-4.2$ /usr/pgsql-10/bin/pg_upgrade -b /usr/pgsql-9.6/bin/ -B /usr/pgsql-10/bin -d /var/lib/pgsql/9.6/data -D /var/lib/pgsql/10/data -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 mismatch       ok
Checking for invalid "unknown" user columns                 ok
Checking for hash indexes                                   ok
Checking for presence of required libraries                 ok
Checking database user is the install user                  ok
Checking for prepared transactions                          ok

*Clusters are compatible* <- This line is VERY IMPORTANT :)
-bash-4.2$