On Sat, Jul 23, 2022 at 11:33 AM Joe Conway <m...@joeconway.com> wrote: > > On 7/22/22 17:18, Zheng Li wrote: > > Here is a patch that supports replication of global object commands, > > these include ROLE statements, database statements and tablespace > > statements. > > The patch should be applied on top of the v13 DDL replication patch set that > > ZJ Hou sent in the previous email. > > > > Global objects commands are different from other DDL commands in > > that: > > 1. Global objects commands are allowed to be executed in any databases > > 2. Global objects are not schema qualified > > 2. Global objects commands are not captured by event triggers > > > > This patch supports global objects commands replication by WAL > > logging the command using the same function for DDL logging - > > LogLogicalDDLMessage, towards the end of standard_ProcessUtility. > > Because global objects are not schema qualified, we can skip the deparser > > invocation and directly log the original command string for replay on > > the subscriber. > > I have not looked at the patch but +1 for the general concept. Seems > like you might want to start a separate thread, perhaps after the > currently running commitfest is over.
Thanks for the suggestion. I'll start a new thread on the replication of global objects commands. I think it's different enough to get its own attention. > > > A key problem is global objects can get inconsistent between the > > publisher and the subscriber if a command changes the global object > > in a database (on the source side) which doesn't configure logical > > replication. > > I think we can work on the following directions in order to avoid such > > inconsistency: > > > > 1. Introduce a publication option for global objects command replication > > and document that logical replication of global objects commands is > > preferred > > to be configured on all databases. Otherwise inconsistency can happen > > if a command changes the global object in a database which doesn't configure > > logical replication. > > > > 2. Introduce database cluster level logical replication to avoid > > such inconsistency, this is especially handy when there is a large > > number of databases to configure for logical replication. > > I would strongly favor #2, although I admittedly have no idea what > complexities it adds. I will also start a new thread once we have more concrete plans on this. Regards, Zheng
