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Re: Attribute of type record has wrong type error with MERGE ... WHEN NOT MATCHED BY SOURCE THEN DELETE

Tender Wang <tndrwang@gmail.com>

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From: Tender Wang <tndrwang@gmail.com>
To: Duncan Sands <duncan.sands@deepbluecap.com>
Cc: pgsql-bugs@lists.postgresql.org
Date: 2025-03-10T12:32:40Z
Lists: pgsql-bugs 
Duncan Sands <duncan.sands@deepbluecap.com> 于2025年3月10日周一 18:43写道：

> Postgresql version 17.4 (Ubuntu 17.4-1.pgdg24.10+2) on x86_64-pc-linux-gnu
>
> To reproduce, execute the statements in the attached file cr.sql.  I get:
>
> duncan=> \i cr.sql
> CREATE TABLE
> CREATE TABLE
> CREATE VIEW
> CREATE TABLE
> COPY 1
> COPY 2
> COPY 1
> psql:cr.sql:42: ERROR:  attribute 2 of type record has wrong type
> DETAIL:  Table has type _country_or_region, but query expects record.
>
> I attribute it to the "WHEN NOT MATCHED BY SOURCE THEN DELETE" part of the
> MERGE
> as it doesn't happen if that part is left off.
>
>
Yeah, I can reproduce this on HEAD, but on 17.0, no error happened.
I searched commit history, I found that this error was related to d7d297f84.

commit d7d297f8449641bfd71750d04c302572a350052c
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
Date:   Thu Oct 3 12:50:38 2024 +0100

    Fix incorrect non-strict join recheck in MERGE WHEN NOT MATCHED BY
SOURCE.

    If a MERGE command contains WHEN NOT MATCHED BY SOURCE actions, the
    merge join condition is used by the executor to distinguish MATCHED
    from NOT MATCHED BY SOURCE cases. However, this qual is executed using
    the output from the join subplan node, which nulls the output from the
    source relation in the not matched case, and so the result may be
    incorrect if the join condition is "non-strict" -- for example,
    something like "src.col IS NOT DISTINCT FROM tgt.col".

Reverted above commit, cr.sql succeeded.

 psql (17.0)
Type "help" for help.

postgres=# \i /workspace/cr.sql
CREATE TABLE
CREATE TABLE
CREATE VIEW
CREATE TABLE
COPY 1
COPY 2
COPY 1
MERGE 0


-- 
Thanks,
Tender Wang

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Repair commits 317aba70e et al for -DWRITE_READ_PARSE_PLAN_TREES.

  2. Build whole-row Vars the same way during parsing and planning.

  3. Preserve RangeTblEntry.relid when expanding a view RTE.

  4. Fix incorrect non-strict join recheck in MERGE WHEN NOT MATCHED BY SOURCE.