A major new release of PostgreSQL, the enterprise-class open source database, is now in beta, and is expected to be released into general availability this summer. PostgreSQL version 9.0 is the first version to include built-in real-time binary database replication with query scale-out, consisting of two features, hot standby and streaming replication.
"One of the reasons we made it a new major version number was specifically because we are adding a lot of major new features that involve changes, some of which are not 100% backwards compatible, and some of which may be less stable than we normally have for a dot-oh release," Josh Berkus, CEO, PostgreSQL Experts, leader of the PostgreSQL Core Team, tells 5 Minute Briefing. This is "simply because the changes are fairly dramatic."
The beta release will undergo testing and user input until the scheduled release in 2 months. "I'm hoping to get the final version out by July, but that's a hypothetical release date, because a lot of it depends on bug fixing," says Berkus.
In version 9.0, new features will allow developers and DBAs to broaden their use of PostgreSQL, including new binary replication. "Binary replication is the number-one people are talking about," Berkus says. That's because Postgres users have had to rely on third-party replication tools such as Slony until now, he explains. These tools have been unnecessarily complex and expensive. "The problem is that Slony is capable of doing all of those things, but that means if you have simplest case, which is you just want to have replication between two machines, the setup is unnecessarily complicated because you're getting all these high-end features even if you're not going to use them."
In addition, Postgres' new binary replication tool addresses concerns about idle warm standby servers. "The problem with the warm standby failover server is that it's not good for being anything other than an insurance policy while it's running," says Berkus. "But you can't actually query it. It's an inert database until it's activated by failover," he points out. "If Postgres is important enough to you to need warm standby in the first place, then chances are you're going to be running it on a $25,000 machine. So having one of those machines effectively idle and only there for insurance doesn't make people happy about their resource usage. The new feature allows people using warm standby and point-in-time recovery to get some additional use out of their standby machine by allowing them to run read-only queries. It's the same as Oracle's hot standby."
In total, there are more than 200 changes made to the database, according to Postgres. Because version 9.0 includes many new major features as well as overhauled internal code, such as changes to the syntax allowed by the PL/PgSQL language, backwards compatibility issues are expected.
Source code, as well as binary installers for many platforms, is available from the PostgreSQL website.