Re: Column Filtering in Logical Replication

On 2021-Sep-27, Amit Kapila wrote:

> I am not sure what makes you say that we can't distinguish the above
> cases when there is already a separate rule for CURRENT_SCHEMA? I
> think you can distinguish by tracking the previous objects as we are
> already doing in the patch. But one thing that is not clear to me is
> is the reason to introduce a new type PUBLICATIONOBJ_CURRSCHEMA when
> we use PUBLICATIONOBJ_REL_IN_SCHEMA and PUBLICATIONOBJ_CONTINUATION to
> distinguish all cases of CURRENT_SCHEMA. Alvaro might have something
> in mind for this which is not apparent and that might have caused
> confusion to you as well?

My issue is what happens if you have a schema that is named
CURRENT_SCHEMA. In the normal case where you do ALL TABLES IN SCHEMA
"CURRENT_SCHEMA" you would end up with a String containing
"CURRENT_SCHEMA", so how do you distinguish that from ALL TABLES IN
SCHEMA CURRENT_SCHEMA, which does not refer to the schema named
"CURRENT_SCHEMA" but in Vignesh's proposal also uses a String containing
"CURRENT_SCHEMA"?

Now you could say "but who would be stupid enough to do that??!", but it
seems easier to dodge the problem entirely. AFAICS our grammar never
uses String "CURRENT_SCHEMA" to represent CURRENT_SCHEMA, but rather
some special enum value.

--
Álvaro Herrera 39°49'30"S 73°17'W — https://www.EnterpriseDB.com/