Oracle's pricing is the main reason why more organisations are moving to Postgres, according to EnterpriseDB, which sells apps and services for the open-source database.
Along with every large telecoms provider, 10 of Europe's 15 largest banks are now running projects on Postgres, EnterpriseDB European managing director Sandor Klein said.
"The number one reason for the growth of Postgres at the moment is the very aggressive pricing of Oracle. People are forced into looking at alternatives to Oracle and then you come to relational databases if you do transactions," Klein said.
"NoSQL is not there yet, and MySQL andare more read-intensive databases. Postgres comes out of Ingres and maybe it's nice to know that it's a true relational database. So if you look at it in that way, it's comparable with Oracle, DB2, Microsoft SQL Server — those kinds of technologies.
"The aggressive pricing policy of Oracle is our best advertisement."
Along with the rise of the cloud, Klein said the success of Postgres lies in its 20-year-old roots in Ingres as a true relational database, giving it great reliability.
"It's so reliable that a lot of large banks run their processes on it, and it's a perfect way of doing transactions. If you go to technology like NoSQL, that's more for big data, and MySQL is more read-intensive," he said.
"It's a $30bn market and 80 percent of that $30bn is being spent on relational databases because you do transactions and companies earn their money by doing transactions."
Klein said the Oracle layer that EnterpriseDB has built on top of Postgres enables applications made for Oracle to run relatively easily with the open-source database.
That technology, combined with a per-socket annual subscription and the absence of vendor lock-in, is adding to the appeal of Postgres, and alliances with HP and IBM have given it an extra boost, he said.
He also said that EnterpriseDB's pricing and product structure will be simplified early next year to increase its transparency.
EnterpriseDB this week announced the latest versions of its management console and database, and a new failover manager, all designed to strengthen Postgres' hand as a mission-critical system.
As well as the expanded JSON support included in September's PostgreSQL 9.3, EnterpriseDB's 9.3 version of Postgres Plus Advanced Server database can handle larger datasets thanks to improvements in partitioning, the company said.
Its Failover Manager is a collection of tools that enable the creation of fault-tolerant database clusters designed to cut downtime and keep the data available if the master database fails.
New features in the Postgres Enterprise Manager 4.0 console include customisable dashboards and new monitoring probes and alerts for log files, SQL injections attacks and replication configurations.
EnterpriseDB Corporation was created in 2004 to provide commercial support and additional features for the community-developed PostgreSQL object-relational database management system.