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 <alvhe...@alvh.no-ip.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) > > >
