"David G. Johnston" <david.g.johnston@xxxxxxxxx> writes: > On Tue, Nov 9, 2021 at 7:50 AM Avi Weinberg <AviW@xxxxxxxxx> wrote: >> Was this done on purpose, that default value for new column is not copied >> for existing data? Does this mean that on destination side we must also >> define the table with default value? > If you run a command on the publisher that causes every row to change then > of course every row will be published with those new values to the > subscriber. I think the important point here is that the ALTER ADD COLUMN operation *didn't* cause a physical update of every row on the publisher, thus nothing got sent to the subscriber. This is sort of annoying, because it is making what ought to be a purely internal optimization user-visible. Depending on the details of the column default (is it null, is it a constant) and which PG version you are talking about, there may or may not be a rewrite of the source table, and here we see that that is semantically visible to subscribers. I don't want to give up the aforesaid optimization --- it's a feature that you can do common forms of ALTER ADD COLUMN in O(1) time. But maybe we ought to document the implications for logical replication better. regards, tom lane
