What PostgreSQL is and why millions choose it

There are hundreds of databases. Dozens of them claim to be the best. But PostgreSQL often stands out even when it is not the first choice. Why? Because it is one of those databases that does everything well and rarely makes you regret choosing it two years later.

PostgreSQL is an open-source relational database. “Open-source” means its code is freely available to inspect, use, and modify. “Relational” means data is stored in tables that can be linked to each other.

If you boil it down to one sentence: PostgreSQL is a reliable store that knows how to safely keep your data and give it back quickly.

The problem: why a database is needed at all

Without a database, applications store data in files or in memory. That works for small scripts, but chaos starts when:

A database solves all of that. It is like a librarian: knows where everything is, prevents two people from changing the same book at once, and guarantees nothing gets lost.

Why PostgreSQL instead of MySQL / SQLite / something else

There is no single right answer. But here is what sets PostgreSQL apart:

1. SQL standards compliance

PostgreSQL follows SQL standards very closely. Queries you write here are more likely to work as intended. MySQL often does “whatever is convenient,” which sometimes leads to surprises.

2. Extensibility

PostgreSQL lets you create custom data types, functions, operators, and even entire languages inside the database. Extensions can add trigram search, geospatial support (PostGIS), full-text search, and much more.

3. Reliability

Transactions, ACID — this is not marketing, these are real guarantees. If a transaction commits, the changes are definitely saved. If something goes wrong — everything rolls back as if nothing happened.

4. JSON and JSONB

PostgreSQL can store and search JSON data right inside tables. You do not have to choose between a relational database and a document store. You can use both.

5. Community and ecosystem

PostgreSQL has been developed by independent contributors for over 30 years. No single company “owns” it. That means no one will suddenly change the rules or start charging for something that was previously free.

How this works in plain language

Imagine you have a web application. Users register, place orders, update profiles. What happens:

  1. The application sends a SQL query to PostgreSQL: “save a new user with name ‘Maria’, email ‘maria@example.com’.”
  2. PostgreSQL checks: does the table exist, is the data type correct, is there a conflict with the unique constraint on email?
  3. If everything is fine — the data goes into the table and the application gets confirmation.
  4. Later another query: “find the user with email maria@example.com.” PostgreSQL finds the right row and returns the data.

All of this works even when thousands of queries arrive at the same time — the database queues them and guarantees data stays consistent.

Core concepts

To work with PostgreSQL, you need to know a few basics:

Database → Tables → Rows → Columns

First commands

-- Create a database
CREATE DATABASE myapp;

-- Connect to the database
\c myapp

-- Create a table
CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    email TEXT UNIQUE NOT NULL,
    created_at TIMESTAMP DEFAULT NOW()
);

-- Insert a row
INSERT INTO users (name, email)
VALUES ('Maria', 'maria@example.com');

-- Find a row
SELECT * FROM users WHERE email = 'maria@example.com';

-- Update a row
UPDATE users SET name = 'Maria Ivanova'
WHERE email = 'maria@example.com';

-- Delete a row
DELETE FROM users WHERE email = 'maria@example.com';

JOIN — linking tables

One of the most important features of a relational database — connecting data across tables:

-- Show orders with user names
SELECT orders.id, users.name, orders.total
FROM orders
JOIN users ON orders.user_id = users.id;

This is like saying: “show me orders, and next to each one, show the name of the person who placed it.”

When PostgreSQL is the best choice

Perfect fit when:

When PostgreSQL might not be the best choice

Skip PostgreSQL when:

Common beginner mistakes

1. Not using indexes

When a table has thousands of rows, a query without an index scans everything. An index on a column you frequently search by is the simplest way to speed up queries 10–100x.

CREATE INDEX idx_users_email ON users(email);

Check query plans with EXPLAIN ANALYZE — PostgreSQL will show you how it executes the query and which indexes it uses.

2. Storing everything in one table

Normalization is not just a textbook word. If you store a user’s address, orders, and change history in one table — queries become slow and difficult.

3. Ignoring transactions

If you are updating multiple tables at once (for example, deducting from one account and crediting another) — wrap them in a transaction:

BEGIN;
  UPDATE accounts SET balance = balance - 100 WHERE id = 1;
  UPDATE accounts SET balance = balance + 100 WHERE id = 2;
COMMIT;

If something goes wrong between these queries, ROLLBACK undoes everything.

4. Forgetting about backups

pg_dump is your friend. Or set up automatic replication. Database loss is usually not a matter of “if” but “when.”

5. Running with default settings

PostgreSQL defaults are tuned for weak hardware (1 GB RAM). On a server with 8–16 GB, you should increase shared_buffers, work_mem, and effective_cache_size. Otherwise the database runs like it is 2010.

Conclusion / action plan

PostgreSQL is a database you can build almost anything on. It is reliable, flexible, open-source, and has a great community.

Here is what to do next:

  1. Launch PostgreSQL via Docker: docker run -e POSTGRES_PASSWORD=test -p 5432:5432 postgres:17.
  2. Connect via psql and create your first database and table.
  3. Run INSERT, SELECT, UPDATE, and DELETE — make sure you understand the basic cycle.
  4. Add an index and compare query performance with EXPLAIN ANALYZE.
  5. Try pg_dump for backup and pg_restore for restore.

A database is the foundation. And PostgreSQL is one of the strongest foundations for an IT project.