On Fri, 29 May 2020 at 17:57, Kyotaro Horiguchi <horikyota....@gmail.com> wrote: > > At Fri, 29 May 2020 16:21:38 +0900, Michael Paquier <mich...@paquier.xyz> > wrote in > > On Thu, May 28, 2020 at 06:11:39PM +0900, Kyotaro Horiguchi wrote: > > > Mmm. It is not the proper way to use physical replication and it's > > > totally accidental that that worked (or even it might be a bug). The > > > documentation is saying as the follows, as more-or-less the same for > > > all versions since 9.4. > > > > > > https://www.postgresql.org/docs/13/protocol-replication.html > > > > + if (am_db_walsender) > > + ereport(ERROR, > > + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), > > + errmsg("cannot initiate physical > > replication on a logical replication connection"))); > > > > I don't agree with this change. The only restriction that we have in > > place now in walsender.c regarding MyDatabaseId not being set is to > > prevent the execution of SQL commands. Note that it is possible to > > start physical replication even if MyDatabaseId is set in a > > replication connection, so you could break cases that have been valid > > until now. > > It donesn't check MyDatabase, but whether the connection parameter > "repliation" is "true" or "database". The documentation is telling > that "replication" should be "true" for a connection that is to be > used for physical replication, and "replication" should literally be > "database" for a connection that is for logical replication. We need > to revise the documentation if we are going to allow physical > replication on a conection with "replication = database". >
Yes. Conversely, if we start logical replication in a physical replication connection (i.g. replication=true) we got an error before staring replication: ERROR: logical decoding requires a database connection I think we can prevent that SEGV in a similar way. Regards, -- Masahiko Sawada http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
