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Let’s Compare: Oracle vs. PostgreSQL

Mohammed Siddiqui | | November 13, 2019

In the simplest form, PostgreSQL is an open-source database, while Oracle is a closed database system. PostgreSQL is a relational object-oriented database management system that is free and developed by volunteer developers worldwide. Oracle is a licensed commercial relational database management system.


While both database systems subscribe to similar concepts such as schemas, tablespaces, and indices, they are starkly different in areas such as replication and support. Oracle DB is implemented in C and C++ while PostgreSQL is written in C language only. Let’s dive in to gain deeper insights into the key differences and similarities between PostgreSQL and Oracle DB.


While both databases offer high availability, Oracle computes higher transactions per second. It is considered more functional than PostgreSQL, but the extra functions come at an additional cost (enterprise editions have higher functionality).

Nonetheless, PostgreSQL offers four levels of transactions – Read Uncommitted, Read Committed, Repeatable Read, and Serializable that give DBAs a range of possibilities. Both of these databases are ACID compliant ensuring that no data is lost during system errors. This facilitates roll-backs and isolation of erroneous data sets.


Oracle and PostgreSQL offer scalable options for developers, but PostgreSQL is more scalable because of its open-source characteristics. For business owners using Oracle, you have to spend more on infrastructure to carry out scalability operations. The standard edition offers four sockets, but if you have high workloads, you will need the enterprise edition.

PostgreSQL developers can scale up operations with ease as the database accommodates any volume of data. It offers free expansion through its cluster-based storage solutions. You can foster integrity while performing scalability operations by using Oracle’s redo logs or PostgreSQL WAL files (has a limited size of 16mb).


Oracle DB has robust security features compared to PostgreSQL. Advanced security options come with higher cost editions. Through security assessments, data protection, as well as auditing and monitoring, Oracle DB is resilient. It edges out PostgreSQL as it offers excellent isolation solutions between pluggable databases and provides independent key encryption management.

PostgreSQL DB also has commendable security fortifications. It has Roles and inherited roles that enables developers to set permissions. It also supports native SSL that assists in encrypting server communications. PostgreSQL has SE-PostgreSQL that provides extra access controls that rely on SELinux security policy.


For Oracle, support is expensive. Large corporations have to hire Oracle consultants or depend on Oracle’s support that costs as much as 25% of the license fees.

On the other hand, PostgreSQL has an active community that offers free online support via blogs, emails, code, etc. There is no listed telephone number to contact in case of emergencies. This is one of the downsides of open-source software. Organizations such as Netflix, Yahoo or Instagram that use PostgreSQL and need premium support can hire Postgres community developers who are less expensive than Oracle’s team. Support is also available from companies like EnterpriseDB and 2nd Quadrant. They also have their own flavor of PostgreSQL.

Compatibility & Replication

Both database systems have unprecedented partitioning capabilities. They support HA solutions where Oracle’s DataGuard resembles PostgreSQL’s Streaming Replication. Both RDBMS supports master-slave replication that gives developers flawless performance when expediting backup, task allocation, and clustering processes. But Oracle outdoes PostgreSQL as it also offers master-master replication.

Both systems support ORM frameworks as well as APIs and access networks such as JDBC, ODBC, OLEDB, and .Net libraries. You need to know that PostgreSQL supports a larger group of APIs than Oracle making it compatible with many applications, add-ons, and SQL environments.

SQL Compliance

SQL implementations for both databases are powerful comprising of cube, rollup, analytics, etc. Oracle has a relatively complex SQL Syntax compared to PostgreSQL. Oracle follows ‘Oraclism’ when developing Syntax while PostgreSQL tends to follow the standard way. Both have non-standard built-in procedural extensions (Oracle PL/SQL and PostgreSQL pg/SQL).

Pg/SQL is slower than Oracle’s PL/SQL, which is a more mature technology. On the flip side, PostgreSQL allows developers to use query handlers such as R and Python to write directly into the database – a feature that is more powerful than Oracle’s Imho.

High Availability

Oracle Real Application Clusters (RAC) enables databases to be shared across a pool of servers. One instance of failure allows the database to run on the remaining databases, thus offering continuous workflow management.

PgpPool available in PostgreSQL Enterprise DB is similar to RAC. If you are familiar with PostgreSQL – XL, you might be aware that it offers high availability through its horizontal scalability option that allows you to add nodes dynamically. The difference between RAC and PgPool is that RAC is an in-built feature. You will have to use a bevy of Clusterware tools in PostgreSQL to achieve RAC’s capabilities.

Migration Tools

PostgreSQL has essential tools that support migration from Oracle. These tools include Ora2Pg for migrating large projects, Oracle_FDW for moving schemas and data and Orafce for fostering compatibility of functions. Code migration can be done using tools such as the AWS Schema Conversion Tool (AWS SCT).

On the other hand, Oracle has features such as Database Replay and SQL Performance Analyzer in its “Real Application Testing” (RAT) that enable you to analyze and test migration requirements. Moving a huge Oracle database to PostgreSQL can consume significant resources and time. PostgreSQL has a stress testing tool called PGREPLAY that can be hacked to stress test large databases.

Backup and Recovery

Data recovery processes in Oracle can be overwhelming. The process is much more straightforward with PostgreSQL where it is a matter of replacing directories and sub-directories plus its associated WAL files.

The backup process for both database systems is straightforward. With PostgreSQL, pgdump and pgbasebackup and Oracle RMAN’s backup, developers can efficiently perform backup and data recovery processes.

Overall, Oracle and PostgreSQL are even regarding their capabilities, performance, and compatibility. Oracle stands tall on matters relating to security, replication, and availability. PostgreSQL has stronger API compatibility, cheaper support, and robust scalability. As DBAs, we think that your choice of database will depend on your needs.

If you love a DB that is easy to use but don’t mind spending time customizing the codes to suit your business, PostgreSQL is your go-to database. For those that cherish high availability and flawless replication during voluminous transactions but don’t mind about overhead costs, Oracle RDBMS can meet your needs.

If you’re looking for further expertise in deciding on a database vendor, please contact us. Datavail has expertise along with leading partnerships with technology providers including Oracle and PostgreSQL among others. We can consult with your organization to determine the best solution for your needs.

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