Re: Question about use_physical_tlist() which is applied on Scan path

On 2023-Jul-26, Jian Guo wrote:

> It looks the columns besides `ps_supplycost` and `ps_availqty` are not
> necessary, but fetched from tuples all at once. For the row-based
> storage such as heap, it looks fine, but for column-based storage, it
> would result into unnecessary overhead and impact performance. Is
> there any plan to optimize here?

I suppose that, at some point, it is going to have to be the table AM
the one that makes the decision. That is, use_physical_tlist would have
to involve some new flag in path->parent->amflags to determine whether
to skip using a physical tlist. Right now, we don't have any columnar
stores, so there's no way to verify an implementation. If you do have a
columnar store implementation, you're welcome to share it.

--
Álvaro Herrera PostgreSQL Developer
"I am amazed at [the pgsql-sql] mailing list for the wonderful support, and
lack of hesitasion in answering a lost soul's question, I just wished the rest
of the mailing list could be like this." (Fotis)
(http://archives.postgresql.org/pgsql-sql/2006-06/msg00265.php)