Question

I’m sure this has been answered but I cannot seem to find an answer.

I installed postgresql using Homebrew (brew install postgresql) which installed to /usr/local/Cellar/postgresql. Afterwords per the instructions I did this:

If this is your first install, create a database with:
    initdb /usr/local/var/postgres

As I understand it, initdb creates a new cluster of databases. So when I did the above is “postgres” the database name and the database itself or just all the necessary bits that all postgresql databases will need?

Where does the actual database end up living? I am new to postgresql and looking for a file or binary that is the database. So, where is the database, and when I create a new one where does it go?

Answer 1

initdb just sets up the directory structure and such that is needed to create new databases. To create a database, use createdb:

SYNOPSIS
createdb [ option… ] [ dbname ] [ description ]

DESCRIPTION
createdb creates a new PostgreSQL database.

Normally, the database user who executes this command becomes the owner
of the new database. However a different owner can be specified via the -O option,
if the executing user has appropriate privileges.

createdb is a wrapper around the SQL command CREATE DATABASE [create_database(7)].
There is no effective difference between creating databases via this utility and
via other methods for accessing the server.

initdb is sort of like creating a new file system on a hard disk: first you create the file system (initdb), then you create a files and directories (createdb).

The actual database files will be under /usr/local/var/postgres after you create the database. So, just create a database and then see what’s new or changed under /usr/local/var/postgres. There isn’t a single “dbname.db” file or anything like that, each database is a collection of files with names that are only meaningful to the database server.