Sun has formed a deal with EnterpriseDB, an open source database vendor, to provide support services around Sun's PostgreSQL offering.

The deal underscores the increasing enterprise viability of PostgreSQL.

The open source database is considered one of the most advanced available, technically speaking, but isn't practical for most large companies because of the lack of an established corporate sponsor offering technical support.

Sun said late last year it would provide support around PostgreSQL, which it recently integrated into its Solaris 10 operating system.

EnterpriseDB, which launched in May 2005, sells a version of PostgreSQL customised to run Oracle applications, along with support.

The deal, announced on Tuesday, will see EnterpriseDB providing Sun with technical support, professional services and training around PostgreSQL. Sun will handle most of its customers' support queries itself, but will turn to EnterpriseDB for more advanced problems.

Sun will also get training for its engineering and technical support teams, and may use EnterpriseDB for consulting services around PostgreSQL architecture and development, the companies said.

Another sign that the market for PostgreSQL-based databases is growing more competitive was the news last week that Pervasive Software would pull the plug on its own offering in the area, Pervasive Postgres.

In an open letter to PostgreSQL developers, Pervasive president John Farr said the company could not compete with other support options.

In February, EnterpriseDB released a major upgrade to its database, incorporating PostgreSQL 8.1.2 as well as new Oracle compatibility features and a integrated debugger.