Re: Support logical replication of DDLs

On 2023-Feb-16, houzj.fnst@fujitsu.com wrote:

> I did some research for this.
> 
> The provider seems not a database object, user needs to register a provider via
> C ode via register_label_provider. And ObjectAddress only have three
> fields(classId, objectId, objectSubId), so it seems hard to set the provider with name to
> a ObjectAddress. We cannot get the correct provider name from the catalog as
> well because there could be multiple providers for the same db object.

Oh, I didn't realize that the provider wasn't an ObjectAddress.  You're
right, that idea won't fly.

> So, if we don't want to modify the parsetree. Maybe we can introduce a function
> GetDefaultProvider() which can be used if user doesn't specify the provider in
> the DDL command. GetDefaultProvider will return the first provider in the
> providers list as is done in ExecSecLabelStmt(). What do you think ?

One of the design principles is that the DDL execution must resolve the
object just once, and thereafter all references must use the same.
Resolving twice via this new GetDefaultProvider would violate that
(consider if you made it a GUC and the user sent the SIGHUP that changed
it just in between.)

I think another workable possibility is to create a new value in
CollectedCommandType, a separate struct in the union of
CollectedCommand, and stash the info about the whole command there,
including the provider; then tell ProcessUtilitySlow that the command
was already stashed.

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
"La conclusión que podemos sacar de esos estudios es que
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