Alex Balashov schrieb am 19.03.2019 um 21:52:
> My experience is that adding a column is a rather quick operation even
> on quite large tables, _unless_ the column has a default value, in which
> case that default value is set for every row. In that case, the time
> required for the operation converges with that of a mass-UPDATE.
Which has changed with Postgres 11, where adding a default value does not update all rows in the table.