Part I dealt with the impact your licensing choice can have on the use of the code you write. This part II focuses on how your choice of license impacts your ability to incorporate third party code.

There were new metrics out this week for both EnterpriseDB's PostgreSQL-centric database business, and Sun Microsystems' MySQL business. These players are at the forefront of challenging pricing for databases and surrounding services from competitors such as Oracle, and both are having strong success with strategies focused on open source databases.

When it comes to open source databases, MySQL gets the lion’s share of attention. This is unfortunate, because out of the two, PostgreSQL offers much more security, reliability, and data integrity than MySQL does.

How many open source relational databases can you name? If you’re like most technical people, you probably don’t know any — just as I didn’t until recently. I can already imagine many of you saying... what about MySQL and PostgreSQL?”, but those are just databases, not relational databases.

Times of change are upon the database market. The major established database companies are being challenged by open source upstarts like MySQL and PostgreSQL. For years, Open Source Databases (OSDBs) have been quietly increasing their penetration, but until recently they have lacked the capabilities to seriously threaten proprietary databases like Oracle, IBM's DB2, and Microsoft's SQL Server.

Contrary to published reports and popular opinion alike, the most important impact of open source on the enterprise has not been on pricing. The single most important impact of open source upon the enterprise has been the removal of barriers to entry and adoption - all thanks to open source’s ability to empower individual developers and architects.

What do all these licenses do for you? That's the 64 license question. Today I'm pondering if the current open source model is still valid or if it's outdated. Do we need licensing for open source software? Do we need the GPL, LGPL, APL and all the other licenses that plague...er, grace us? If your software is free and open source, why bother with a license at all?

There was some interesting discussion following my post last week asking whether there is a growing rift between commercial open source software vendors and some aspects of the open source user community.

What's the most popular open source license currently in use? If you said GPL you would be right. But how did you know?