Re: Support logical replication of DDLs

On Tue, 29 Nov 2022 at 17:51, li jie <ggysxcq(at)gmail(dot)com> wrote:
>
> I will continue to give feedback for this patch.

Thanks a lot, that will be very helpful for us.

> 1. LIKE STORAGE
> ```
> CREATE TABLE ctlt (a text, c text);
> ALTER TABLE ctlt ALTER COLUMN c SET STORAGE EXTERNAL;
> CREATE TABLE ctlt_storage (LIKE ctlt INCLUDING STORAGE);
> ```
>
> postgres=# \d+ ctlt_storage
>
> Table "public.ctlt_storage"
>
> Column | Type | Collation | Nullable | Default | Storage |
> Compression | Stats target | Description
>
> --------+------+-----------+----------+---------+----------+-------------+--------------+-------------
>
> a | text | | | | extended |
> | |
>
> c | text | | | | extended |
> | |
>
>
> It can be seen that the storage attribute in column C of table
> ctlt_storage is not replicated.
>
> After the CREATE TABLE LIKE statement is converted,
> the LIKE STORAGE attribute is lost because it is difficult to display
> it in the CREATE TABLE syntax.
> Maybe we need to add a statement to it, like 'ALTER TABLE ctlt_storage
> ALTER COLUMN c SET STORAGE EXTERNAL;'.
>
> 2. Reference subcommand be dropped.
> ```
> create table another (f1 int, f2 text, f3 text);
>
> alter table another
> alter f1 type text using f2 || ' and ' || f3 || ' more',
> alter f2 type bigint using f1 * 10,
> drop column f3;
> ```
>
> The following error occurs downstream:
> ERROR: column "?dropped?column?" does not exist at character 206
> STATEMENT: ALTER TABLE public.another DROP COLUMN f3 , ALTER COLUMN
> f1 SET DATA TYPE pg_catalog.text COLLATE pg_catalog."default" USING
> (((f2 OPERATOR(pg_catalog.||) ' and '::pg_catalog.text)
> OPERATOR(pg_catalog.||) "?dropped?column?") OPERATOR(pg_catalog.||) '
> more'::pg_catalog.text), ALTER COLUMN f2 SET DATA TYPE pg_catalog.int8
> USING (f1 OPERATOR(pg_catalog.*) 10)
>
> Obviously, column f3 has been deleted and its name no longer exists.
> Maybe we need to keep it and save it in advance like a drop object.
> However, ATLER TABLE is complex, and this problem also occurs in
> other similar scenarios.

I will analyze these issues and post a patch to handle it.

Regards,
Vignesh