Re: Data is copied twice when specifying both child and parent table in publication

On Fri, Mar 17, 2023 at 11:58 AM wangw(dot)fnst(at)fujitsu(dot)com
<wangw(dot)fnst(at)fujitsu(dot)com> wrote:
>
> On Thu, Mar 16, 2023 at 20:25 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
>
> Thanks for your comments.
>
> > + if (server_version >= 160000)
> > + {
> > + appendStringInfo(&cmd, "SELECT DISTINCT N.nspname, C.relname,\n"
> > + " ( SELECT array_agg(a.attname ORDER BY a.attnum)\n"
> > + " FROM pg_attribute a\n"
> > + " WHERE a.attrelid = GPT.relid AND a.attnum > 0 AND\n"
> > + " NOT a.attisdropped AND\n"
> > + " (a.attnum = ANY(GPT.attrs) OR GPT.attrs IS NULL)\n"
> > + " ) AS attnames\n"
> > + " FROM pg_class C\n"
> > + " JOIN pg_namespace N ON N.oid = C.relnamespace\n"
> > + " JOIN ( SELECT (pg_get_publication_tables(VARIADIC
> > array_agg(pubname::text))).*\n"
> > + " FROM pg_publication\n"
> > + " WHERE pubname IN ( %s )) as GPT\n"
> > + " ON GPT.relid = C.oid\n",
> > + pub_names.data);
> >
> > The function pg_get_publication_tables() has already handled dropped
> > columns, so we don't need it here in this query. Also, the part to
> > build attnames should be the same as it is in view
> > pg_publication_tables.
>
> Agree. Changed.
>
> > Can we directly try to pass the list of
> > pubnames to the function pg_get_publication_tables() instead of
> > joining it with pg_publication?
>
> Changed.
> I think the aim of joining it with pg_publication before is to exclude
> non-existing publications.
>

Okay, A comment for that would have made it clear.

> Otherwise, we would get an error because of the call
> to function GetPublicationByName (with 'missing_ok = false') in function
> pg_get_publication_tables. So, I changed "missing_ok" to true. If anyone doesn't
> like this change, I'll reconsider this in the next version.
>

I am not sure about changing missing_ok behavior. Did you check it for
any other similar usage in other functions?

+ foreach(lc, pub_elem_tables)
+ {
+ published_rel *table_info = (published_rel *) malloc(sizeof(published_rel));

Is there a reason to use malloc instead of palloc?

--
With Regards,
Amit Kapila.