Inspecting the changes

As we did not make any changes to the default options, the installation files will be at /usr/local/pgsql. In this, we have four directories, namely include, lib, share, and bin. The include directory contains header files (.h) extension, and the lib directory contains all the libraries to be linked dynamically (.so in the case of Linux/Unix systems and .dll in the case of Windows systems). The bin directory, of course, contains executables.

It is the share directory that is a bit more interesting. Here, we have a number of sample files, namely, pg_hba.conf.sample, pg_ident.conf.sample, pg_service.conf.sample, postgresql.conf.sample, psqlrc.sample, and recovery.conf.sample. Once we initialize a cluster and make changes to various configuration files and then lose track of the changes, we can compare with these files and understand what changes have been made or roll back the changes if necessary.

This directory also has a few SQL files such as information_schema.sql and system_view.sql, which go into creating metadata views when a database cluster is initialized.

At the next level of directories under share, we have the doc directory that holds the documentation, and the man directory that holds the manual pages, and so on. The directory of interest under share is the one named extension. Here, we can see all the extensions, which we can install as per our need. Most extensions have a .control file that provides basic information, as shown here:

[jay@MyCentOS extension]$ more dblink.control
# dblink extension
comment = 'connect to other PostgreSQL databases from within a database'
default_version = '1.1'
module_pathname = '$libdir/dblink'
relocatable = true

There will be SQL files that correspond to each extension, and these will be used when we install the extension in a database we choose.

The documentation to install PostgreSQL from source is at http://www.postgresql.org/docs/current/static/installation.html.

Note that we have just installed the database software. There is no database available to connect to yet. Adding a user for the database administration tasks and initializing a database cluster are the next steps.