Subject: Discarded adjust_relid_set() return values in remove_self_join_rel

From: SATYANARAYANA NARLAPURAM <[email-masked]>
Date: Sat, 25 Apr 2026 00:44:01 -0700

Hi hackers,

I found that remove_self_join_rel() in analyzejoins.c discards the
return values of two adjust_relid_set() calls when updating
root->all_result_relids and root->leaf_result_relids:

    adjust_relid_set(root->all_result_relids, toRemove->relid,
toKeep->relid);
    adjust_relid_set(root->leaf_result_relids, toRemove->relid,
toKeep->relid);

adjust_relid_set() does not modify its input in-place.  When it finds
the old relid in the set, it calls bms_copy() to create a new
Bitmapset, performs the substitution on the copy, and returns the new
pointer.  Without capturing the return value, the original sets are
never updated. Every other call site in the file  analyzejoins.c correctly
assigns the return value.

I am not able to craft a query to show it as a problem.
For the current release, these two lines appears to be a no-op?

Attached a patch to assign the returned values.

Thanks,
Satya

---

From: Tender Wang <[email-masked]>
Date: Sat, 25 Apr 2026 15:53:31 +0800

Hi,

SATYANARAYANA NARLAPURAM <[email-masked]> 于2026年4月25日周六 15:44写道：
>     adjust_relid_set(root->all_result_relids, toRemove->relid, toKeep->relid);
>     adjust_relid_set(root->leaf_result_relids, toRemove->relid, toKeep->relid);
>

The topic in [1] seems to be the same issue as your report.
You can take a look at [1] to double-check.

[1] https://www.postgresql.org/message-id/CAMbWs49fYQcqJfJ_Gtn8r1GFNoYtb1%3D2AUab4ieuqY4Zid9ocQ%40mail.gmail.com
(Sorry for not adding pgsql-hackers mail  in the last email)

-- 
Thanks,
Tender Wang