[hdabrows]

> ... and this is a close second favorite. Having NOT NULL constraints on columns makes schemas much more pleasant to work with, but for schema migrations that means requiring DEFAULT clause to populate existing data. While there are ways to slowly migrate to a NOT NULL / DEFAULT config for a new column (e.g. add column without constraint, migrate data piecemeal, likely in batches of N records, then enable constraint), having it for free in core without rewriting the table at all is simply awesome.

I'm not 100% sure but I don't think that's what it says. If you create a nullable column with a non-null default it won't rewrite the whole table anymore. You could get this behaviour in PostgreSQL 10 by creating the column and setting its default in separate DDL statements (all in a single transaction).

[anarazel]

> You could get this behaviour in PostgreSQL 10 by creating the column and setting its default in separate DDL statements (all in a single transaction).

But that'd mean that the existing columns wouldn't have the DEFAULT value. And thus manually would have to update the whole table. Whereas the facilities in 11 set it on all columns without rewriting the whole table.