Thread

1. Discarded adjust_relid_set() return values in remove_self_join_rel

   SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com> — 2026-04-25T07:44:01Z

   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
   

2. Re: Discarded adjust_relid_set() return values in remove_self_join_rel

   Tender Wang <tndrwang@gmail.com> — 2026-04-25T07:53:31Z

   Hi,
   
   SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com> 于2026年4月25日周六 15:44写道：
   >
   > 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.
   
   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