cPsql:
PostgreSQL Automation Utilities in C

This is a set of programs that use C to interact with a PostgreSQL database. While useful in it's unmodified state for automating table updates, this also serves as an example of how to use the otherwise opaque Postgres C libraries for controlling PostgreSQL servers and their databases.

Why cPsql?

There are many closed-source database management programs available for PostgreSQL that do almost everything for you. If you, dear reader, are anything like myself, then standalone proprietary software that "Does Almost Everything!"™ smells of bloat and engineered dependance. The vast majority of use-cases for such programs can and should be handled by a single C function, especially whenever a particular operation needs to be integrated into another piece of software, or to run with maximum time/space efficiency for deployment at scale. This software demonstrates how such a thing can be done, and will soon include a set of convenient C/C++ headers for the minimalist developer.

How To Compile

PSA

The provided installation script setup.sh should run fine on any Debian or RedHat Linux system. Read it before you run it!

Debian and RedHat Linux

• Clone this repository.
• Read setup.sh.
• Then compile the with:

cd /path/to/this/repository
sudo bash setup.sh

• That's it!
• Optionally: follow the testing instructions described below.

Windows

• Coming Soon.

Mac

• Coming Soon.

Testing:

It's a good idea to check your installation by running cPsqlDemo.bin (compiled in the step above). This is a C script that attempts to connect to a ProstgreSQL server and perform some operations on whatever database you point it at.

Specifically, it does this list of things, in order:

1. Prompts the user for a host IP address, port number, role/username, database name, and password with which to forge a connection to a running PostgreSQL server. (To get past this step, you will need to provide connection info to an actual database, but I trust you can manage that on your own if you don't have one laying around already.)

2. Attempts to forge a connection with the provided credentials and prints out the server version as a proof-of-life. Otherwise prints an error message and exits.

3. Drops any tables in the database named "cPsql_demo_users" or "cPsql_demo_cars" and recreates them with certain constraints on their columns. In particular, the car_id column of cPsql_demo_users is referenced to the id column of cPsql_demo_cars so that each user can be assigned at most one car from the cars table, and only those cars are allowed.

   If by some cosmic coincidence you already have tables with these names in your database:

   1. Buy a lottery ticket and PayPal half your winnings to watch.closely.0@gmail.com (Unintuitive, certainly, but rest assured; this step is crucial to assuage the wrath of the Karmic Random Number Gods).
   2. Make a new db before running this program.

4. Populates these tables with a load of mock data from the CSV files in the folder labeled accordingly. This program buffers files in small sets of lines at once, dynamically allocating only as much memory as needed for each chunk. This means it is able to transmit tables of any size with minimum memory usage and a maximum that can be specified. (so long as your device has the memory to store any single line of the table at once).

5. After data transfer, adds a couple more constraints to these tables, requiring each user have a unique email address, and a unique car_id, or none at all.

6. Assigns some random people random cars.

7. Cleans up.

8. Prints "Success!" and exits.

All this is done with a ton of error checking along the way to ensure everything goes as intended and any errors are reported if they exist.

Contributing

For contributors to the project; do this before making your first commit:

• Install pre-commit

cd /path/to/this/repository/
sudo apt install pre-commit
pre-commit install

(we do all of our development on linux)

• To test updates to the readme and other GitHub flavored markdown, simply install Grip and feed it your desired file.

pip3 install grip
grip README.md

• Then follow the link provided by the Grip sever for a live preview of your work.

• When satisfied with your changes you can compile to an html file with:

grip README.md --export README.html

Authors

• Gabe M. LaFond - Initial work - ExamDay

See also the list of contributors who participated in this project.

License

This project is licensed under the MIT License - see the LICENSE.md file for details