Re: BUG #18902: TRAP:: failed Assert("!is_sorted") in File: "createplan.c"

Tender Wang <tndrwang(at)gmail(dot)com> 于2025年4月23日周三 19:03写道：

>
> I remove the Assert(!is_sorted), its plan looks like as below after adding
> below codes:
> if (presorted_keys > 0 && presorted_keys <
> list_length(best_path->outersortkeys))
> use_incremental_sort = true;
>
> QUERY PLAN
>
>
> ---------------------------------------------------------------------------------------------
> LockRows
> -> Merge Join
> Merge Cond: (local_tbl.c1 = ft1.c2)
> -> Index Scan using local_tbl_pkey on local_tbl
> -> Sort
> Sort Key: ft1.c2
> -> Foreign Scan
> Relations: (((ft1) INNER JOIN (ft2)) INNER JOIN
> (ft4)) INNER JOIN (ft5)
> -> Merge Join
> Merge Cond: (ft1.c2 = ft5.c1)
> -> Sort
> Sort Key: ft1.c2
> -> Merge Join
> Merge Cond: (ft1.c2 = ft4.c1)
> -> Sort
> Sort Key: ft1.c2
> -> Merge Join
> Merge Cond: (ft1.c1 =
> ft2.c1)
> -> Sort
> Sort Key: ft1.c1
> -> Foreign Scan
> on ft1
> -> Sort
> Sort Key: ft2.c1
> -> Foreign Scan
> on ft2
> -> Sort
> Sort Key: ft4.c1
> -> Foreign Scan on ft4
> -> Sort
> Sort Key: ft5.c1
> -> Foreign Scan on ft5
>

If is_sorted is true, it means that it's already fully sorted, the Sort
node doesn't need any more.
I suspect something went wrong somewhere else. I didn't look into the
details.

--
Thanks,
Tender Wang