One Question I Often Hear From Database Professionals

Over the years working with different database platforms — SQL Server, Oracle, PostgreSQL, and MySQL — one question appears frequently among developers and DBAs:

Why do PostgreSQL and Oracle look so similar?

When you start working with both systems, you quickly notice that many commands feel almost identical.

Examples include:

• SELECT
• JOIN
• CREATE TABLE
• CREATE INDEX
• GROUP BY
• ORDER BY

Even advanced concepts like:

• stored procedures
• triggers
• transactions
• constraints

follow very similar patterns.

But this is not a coincidence.

There are historical, technical, and market-driven reasons behind this similarity.

Understanding these reasons helps professionals better understand how the database ecosystem evolved over the last four decades.

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The Real Reason: The SQL Standard

The biggest reason for the similarity between PostgreSQL and Oracle is the SQL standard defined by ANSI and ISO.

SQL was designed to be a universal language for relational databases.

The goal was simple:

Allow developers to interact with different database systems using a common language.

Because of this, core SQL commands are standardized.

Examples:

SELECT
INSERT
UPDATE
DELETE

These commands behave almost the same across major relational databases, including:

• PostgreSQL
• Oracle
• SQL Server
• MySQL
• MariaDB

This standardization created enormous benefits for the industry.

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Why SQL Standardization Was So Important

Without SQL standardization, every database vendor would have created its own language.

That would have created massive problems such as:

• extremely high training costs
• difficult system migrations
• vendor lock-in
• fragmented developer skills

Instead, SQL became a common language for data.

This allowed developers to move between platforms much more easily.

And this is one of the reasons why database professionals today can learn multiple systems relatively quickly.

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Oracle’s Massive Historical Influence

Another important factor is Oracle’s early dominance in the relational database market.

Oracle was released in 1979, becoming one of the first commercially successful relational database management systems.

For many years, Oracle was considered the gold standard for enterprise databases.

Because of this, many later database systems — directly or indirectly — adopted similar ideas.

PostgreSQL itself originated from an academic project called Postgres, started at the University of California, Berkeley in 1986.

Although PostgreSQL evolved independently, the success of Oracle strongly influenced the expectations of database users.

As a result, PostgreSQL incorporated many features that developers already expected to see.

Examples include:

• ACID-compliant transactions
• stored procedures
• triggers
• indexing strategies
• constraint enforcement

These features were already widely used in Oracle environments.

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Procedural Languages: PL/SQL vs PL/pgSQL

Another area where similarities appear is procedural languages.

Oracle uses:

PL/SQL

PostgreSQL uses:

PL/pgSQL

Both allow developers to write structured procedural logic directly inside the database.

They support:

• variables
• loops
• conditional logic
• exception handling
• functions
• triggers

Example structure:

BEGIN
   -- logic
END;

The syntax is not identical, but the design philosophy is extremely similar.

This allows developers familiar with Oracle to adapt to PostgreSQL relatively quickly.

---

Market Pressure and the Demand for Portability

In the enterprise world, companies rarely stay with one technology forever.

Over time, organizations may migrate systems due to:

• licensing costs
• infrastructure changes
• cloud adoption
• performance requirements
• vendor strategy

Because of this, database vendors learned that compatibility is a huge advantage.

If two systems are similar, migration becomes easier.

And easier migrations mean more adoption.

Tools such as:

Oracle2PostgreSQL

exist precisely because many commands and structures are already similar.

Without these similarities, migrations would be significantly more difficult.

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Competition Also Shapes Database Features

Competition between database platforms also pushes vendors to adopt similar features.

For example:

PostgreSQL became extremely strong in handling JSON and semi-structured data.

Oracle later introduced similar capabilities in newer versions.

Likewise, both systems continue improving areas such as:

• query optimization
• indexing
• partitioning
• parallel execution
• replication

Each platform constantly evolves while observing what the other is doing.

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But PostgreSQL and Oracle Are Still Very Different

Despite the similarities, important differences remain.

---

Licensing Model

This is one of the biggest differences.

PostgreSQL

• fully open source
• free to use
• community driven

Oracle

• commercial licensing
• enterprise support model
• expensive for large environments

This difference alone has driven many companies to migrate to PostgreSQL.

---

Architecture Philosophy

Oracle focuses heavily on integrated enterprise solutions, offering a full ecosystem including:

• database
• middleware
• cloud
• enterprise tools

PostgreSQL focuses on flexibility and extensibility, allowing the community to extend the database through plugins and extensions.

Examples:

• PostGIS
• TimescaleDB
• Citus

---

Syntax Differences Still Exist

Although the core SQL language is similar, some syntax differences remain.

For example:

• procedural language syntax
• system catalog views
• administrative commands
• optimizer behavior

A developer moving between platforms must still learn these nuances.

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A Personal Perspective After Working With Multiple Databases

From my experience working with multiple database technologies, one thing becomes very clear.

The most important skill for database professionals is not memorizing syntax.

It is understanding how relational databases work internally.

Once you understand concepts like:

• transactions
• indexing
• query optimization
• locking
• concurrency control

Switching between databases becomes much easier.

The syntax may change slightly, but the fundamental concepts remain the same.

That is why experienced DBAs can adapt quickly to new platforms.

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Final Thoughts

The similarities between PostgreSQL and Oracle are not accidental.

They are the result of:

• SQL standardization
• historical influence
• market demand
• competition
• shared design principles

This convergence has helped create a database ecosystem where professionals can move between platforms more easily.

And for developers and DBAs, that is a huge advantage.

Because in the end, what really matters is not the database brand.

It is the ability to understand data systems deeply and design reliable architectures around them.

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