Room: Room 2
One of the main reasons we hear for not being able to migrate from Oracle to PostgreSQL is the fact that “We absolutely, definitively must have RAC”. Despite its cost and complexity, RAC is widely used in response to a variety of (real or imagined) performance, high availability and/or scalability requirements. PostgreSQL does not have an equivalent to RAC. But does anyone really need it? In his 2003 white paper “You probably don’t need RAC”, Mogens Norgaard asserts that “If you have a system that needs to be up and running a few seconds after a crash, you probably need RAC. If you cannot buy a big enough system to deliver the CPU power and or memory you crave, you probably need RAC… Otherwise, you probably don’t need RAC. Alternatives will usually be cheaper, easier to manage and quite sufficient”. Does this statement still hold true and what are the alternatives that are available to us in PostgreSQL?