Most people don't operate in a 100% ACID environment. However, This has a pretty low impact on web applications, so many of us can breathe easy. PostgreSQL's de

Most people don't operate in a 100% ACID environment. However, This has a pretty low impact on web applications, so many of us can breathe easy. PostgreSQL's default isolation level is READ COMMITTED and InnoDB's default isolation level is REPEATABLE READ. While this might seem like a big difference, the SQL standard is pretty loose in the definition of these, and because of their implementations, they have roughly equivalent consequences. From what I understand, most InnoDB users that demand better performance in high concurrency situations switch the default to READ COMMITTED.