PostgreSQL Version 9.5, 10.x and 12

PostgreSQL Version 9.5, 10.x and 12
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We are in the process of adding support for PostgreSQL to WACS and hope it will be part of the Wacs 1.0.0 release. Please check the release notes for the up-to-date position of this support, but we are hoping it will prove fully functional. Some of the customisation available with other databases may not be available.

Note

	Note
We have created a wacs-for-psql package for both Fedora and Ubuntu that attempts do to what is necessary to create a working Wacs installation. To this end, we create the basic database and a special `wacsdba` database administrator account while in the package's own post-install script. As this is run as root on the machine, it is capable of doing things in the way necessary for those steps in the PostgreSQL way of working.

We have created a wacs-for-psql package for both Fedora and Ubuntu that attempts do to what is necessary to create a working Wacs installation. To this end, we create the basic database and a special wacsdba database administrator account while in the package's own post-install script. As this is run as root on the machine, it is capable of doing things in the way necessary for those steps in the PostgreSQL way of working.

PostgreSQL Installation Basics

PostgreSQL is rather different from Oracle and MySQL as it tends towards using the host operating system authentication mechanisms for identifying users rather than a more conventional username and password combination. It can be reconfigured to allow username and password login, and we attempt to do this in as minimalist a way as possible to preserve normal operation for other users of the database. By default, the system manager account, postgres gains automatic database manager authority when it invokes any of the postgres tools (like the SQL command line, psql).

Warning

	Warning
NB: some Linux distributions, eg Ubuntu, support simultaneous installation of multiple versions of Postgresql. In this case, you may find that the TCP/IP port number on which the database listens has changed from the default of 5432. In one case on an Ubuntu Xenial system which had been upgraded from previous releases; PostgreSQL 9.1 had port 5432, PostgreSQL 9.3 had port 5433 and PostgreSQL 9.5 had 5434. All of these are configured in `/etc/postgres/<release_no>/main/postgresql.conf` so do check the port = directive to make sure you are connecting to the version of the database you think you are.

NB: some Linux distributions, eg Ubuntu, support simultaneous installation of multiple versions of Postgresql. In this case, you may find that the TCP/IP port number on which the database listens has changed from the default of 5432. In one case on an Ubuntu Xenial system which had been upgraded from previous releases; PostgreSQL 9.1 had port 5432, PostgreSQL 9.3 had port 5433 and PostgreSQL 9.5 had 5434. All of these are configured in /etc/postgres/<release_no>/main/postgresql.conf so do check the port = directive to make sure you are connecting to the version of the database you think you are.

A key point to understand is that the Perl DBD driver and similar interfaces to PostgreSQL use the network domain rather than the named pipe for communication and this is not by default enabled by the installation packages for PostgreSQL. In the next section, we will take you through the setup and configuration steps needed for PostgreSQL to interact with the network properly.

Enabling Network Operation In PostgreSQL

There are three steps you need to take to enable network-based operation in postgres; to do these as described belowe you will need access to either the postgres or root accounts for the server computer. If you do not have access to this, there may be other ways to do what is needed via cPanel or similar but you will have to consult a suitable administrator for the system you are using.

Getting PostgreSQL to Listen

The first thing we need to do is to get the PostgreSQL server to listen for connections on the network port. This is done by editing the postgresql.conf file which can be found in /etc/postgresql/10/main for PostgreSQL 10 or in /etc/postgresql/9.5/main PostgreSQL 9.5.

To use WACS effectively the database is all managed under a dedicated WACS user account and it is thus easier to provide username and password without the normal host-based user authentication taking place. If you wish to use the interactive PostgreSQL command line interpreter, psql for fixing up issues or making ad hoc database queries, it is best to use the -h option with the host name of the database service. You will also need the -U option to specify the username to use, and maybe -W to force interactive prompts for the password (optional). A sample invocation of the psql SQL command line would therefore be:

psql -d wacs -h myserver -U wacs

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