The free or GPL RDBMS appeared on the marketplace in the mid 90′s. Initially considered as low range products, they progressively gained market share until the point that they are now frequently used for small to mid-size projects, or non critical projects. When one talks about those products, two names always come to mind: postgreSQL and mySql. Both systems are good products, but they may not be the right choice if the data volume, or even the number of users, grow more than expected.
Despite appearences, a free RDBMS is not as free as it looks, at least until some point. The risk of encountering a dead-end is high, and rebuilding a project from scratch on another RDBMS technology will cost a lot of time and money.
The IBM Informix team understood that point and introduced in 2010 a free of charge production edition of the most reliable and fast RDBMS engine: IBM Informix.
Read here why you should seriously consider to adopt IBM Informix Innovator-C Edition against postgreSQL or mySQL.