Re: BUG #19102: Assertion failure in generate_orderedappend_paths with aggregate pushdown
Andrei Lepikhov <lepihov@gmail.com>
From: Andrei Lepikhov <lepihov@gmail.com>
To: Richard Guo <guofenglinux@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org, akorotkov@postgresql.org,
Kuntal Ghosh <kuntalghosh.2007@gmail.com>
Date: 2025-11-04T13:43:05Z
Lists: pgsql-bugs
On 4/11/2025 08:44, Richard Guo wrote: > Any thoughts?The first patch looks good, but I still have a couple of questions. 1. We don't use parameterised paths in MergeAppend yet. I wonder if it could be nudged by spreading the use of partitioned tables with foreign partitions. Do you think, in such a case, the usage of cheapest_total->rows will stay correct? It seems that the parameterised path has much less estimation than the RelOptInfo... 2. I understand why the upper relation has unset nrows. However, it may be more accurate to set row estimation for a pushing-down upper RelOptInfo. Or, at least, describe in comments why this is desirable behaviour. It would be profitable, at least, for extension developers. I also support the second patch. With many partitions, it allows us to save a significant amount of CPU cycles. -- regards, Andrei Lepikhov, pgEdge