On 2016-02-17 09:33:56 +0800, Craig Ringer wrote:
> Some DDL operations don't translate well to a series of replicatable
> actions. The case I hit the most is
>
> ALTER TABLE mytable ADD COLUMN somecolumn sometype NOT NULL DEFAULT
> some_function();
>
> This is executed (simplified) by taking an ACCESS EXCLUSIVE lock, changing
> the catalogs but not making the changes visible yet, rewriting the table,
> and committing to make the rewritten table and the catalog changes visible.
>
> That won't work well with logical replication.
FWIW, I think this is much less a fundamental, and more an
implementation issue. Falling back to just re-replicating the table, and
then optimizing a few common cases (only immutable DEFALUT/USING
involved) should be enough for a while.
Lets get the basics right, before reaching for the moon.
Greetings,
Andres Freund
