The result of this strategy is an extraordinary lack of cruft. Postgres has some obscure unpopular features, but it really doesn't have any legacy behaviour. I

The result of this strategy is an extraordinary lack of cruft. Postgres has some obscure unpopular features, but it really doesn't have any legacy behaviour. If you read the MySQL documentation, it's full of "until version 5.7.7.3 this returned NULL if..." or "this will accept invalid dates unless a certain mode flag is enabled" (I'm paraphrasing, obviously). Postgres has none of this. They do occasionally deprecate features, such as OIDs, which are supported but not recommended (or particularly useful), or they change some key behaviour (standard_conforming_strings). Sometimes the development strategy leads to incomplete or overlapping functionality because they prefer discrete, additive changes over big, one-off overhauls. But in general, Postgres' conservative strategy has really paid off.