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

I had the same question recently. In addition, I looked at the results of
tpch which scale factor is 1 ran on postgres REL_15_STABLE and observed no
performance improvement from physical tlist. To be specific, I run two
versions of tpch, one with physical tlist enabled and one with physical
tlist disabled. The performance improvement of some queries in the former
was less than 5%, some queries performed worse than latter, and I think
this is a normal range of performance fluctuations which was not caused by
physical tlist. I have read the relevant commits, maybe because of my
carelessness, I did not find the test queries corresponding to physical
tlist. Are there any test queries of physical tlist?
Thanks

Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> 于2023年7月26日周三 18:16写道：

> 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)
>
>
>