Re: Skipping schema changes in publication

Hi Shlok,

I was looking at the recent v24 changes.

======
GENERAL.

I saw that you modified the system view to add a new flag:

+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>exceptcol</structfield> <type>bool</type>
+ </para>
+ <para>
+ True if a column list with <literal>EXCEPT</literal> clause is specified
+ for the table in the publication.
+ </para></entry>
+ </row>

So output now might look like this:

+CREATE TABLE pub_test_except1 (a int NOT NULL, b int, c int NOT NULL, d int);
+CREATE PUBLICATION testpub_except FOR TABLE pub_test_except1,
pub_sch1.pub_test_except2 EXCEPT (b, c);
+SELECT * FROM pg_publication_tables WHERE pubname = 'testpub_except';
+ pubname | schemaname | tablename | attnames |
rowfilter | exceptcol
+----------------+------------+------------------+-----------+-----------+-----------
+ testpub_except | public | pub_test_except1 | {a,b,c,d} | | f
+ testpub_except | pub_sch1 | pub_test_except2 | {a,d} | | t
+(2 rows)

~~~

I think this was done in response to a comment from Vignesh [1], but
it did not get implemented in the way that I had imagined. e.g. I
imagined the view might be more like this:

+ pubname | schemaname | tablename | attnames |
rowfilter | exceptcols
+----------------+------------+------------------+-----------+-----------+-----------
+ testpub_except | public | pub_test_except1 | {a,b,c,d} | |
+ testpub_except | pub_sch1 | pub_test_except2 | {a,d} | | {b,c}

I don't know if broadcasting to the user what the unpublished/hidden
columns' names are is very wise (e.g. "{password,internal_notes,
salary}", but OTOH just having a boolean flag saying that "something"
was excluded ddin't seem useful.

~

Furthermore, having a Boolean seemed strangely incompatible with a
normal column list. e.g. Lets say there is a table T1 with cols
c1,c2,c3,c4.

I could publish that as "FOR TABLE T1(c1,c2,c3)"
Or as "FOR TABLE T1 EXCEPT (c4)"

In the v24 implementation, AFAIK, the view will show those as
"attnames = {c1,c2,c3}", and except will be both "f" and "t". It
seemed odd to.

~

Lastly, I think the EXCEPT (col-list) feature was mostly added just
to help users with 100s of columns to write their CREATE PUBLICATION
statement more easily. Since the view already shows all the columns
that will be published. So, I'm kind of -0.5 on this idea of changing
the view to show how they typed their statement.

======
[1] https://www.postgresql.org/message-id/CALDaNm32XQDR4qsOhPQeophVbZ8r%2BShJSSssoVfdPcwG6joPHQ%40mail.gmail.com

Kind Regards,
Peter Smith.
Fujitsu Australia