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1. BUG #18803: ERROR: wrong varnullingrels (b) (expected (b 4)) for Var 2/1

   PG Bug reporting form <noreply@postgresql.org> — 2025-02-11T14:15:51Z

   The following bug has been logged on the website:
   
   Bug reference:      18803
   Logged by:          Marko Tiikkaja
   Email address:      marko@joh.to
   PostgreSQL version: 16.6
   Operating system:   Linux
   Description:        
   
   Given this schema:
   
   BEGIN;
   CREATE TABLE Users();
   CREATE TABLE Orders(MessageID text);
   CREATE TABLE Transfers (TransferID bigint);
   COMMIT;
   
   
   Running this query:
   
   DO $$
   BEGIN
   
   EXECUTE $SQL$
       SELECT
           CASE WHEN $1 < 1
               THEN 1
               ELSE sum(1) OVER ()
           END AS Total,
           MessageID
       FROM (
           SELECT
               coalesce(
                   ECR.MessageID,
                   Orders.MessageID
               ) AS MessageID
           FROM Orders
           LEFT JOIN LATERAL (
               SELECT
                   Transfers.TransferID || Orders.MessageID AS MessageID
               FROM Transfers
           ) ECR ON TRUE
       ) Txn
   $SQL$
       USING 1;
   
   END
   $$;
   
   produces the following error:
   
   ERROR:  wrong varnullingrels (b) (expected (b 4)) for Var 2/1
   
   (where the "1" seems to correspond to the pg_attribute.attnum of
   Orders.MessageID)
   
   

2. Re: BUG #18803: ERROR: wrong varnullingrels (b) (expected (b 4)) for Var 2/1

   Tom Lane <tgl@sss.pgh.pa.us> — 2025-02-11T15:33:38Z

   PG Bug reporting form <noreply@postgresql.org> writes:
   > Given this schema:
   > ...
   > Running this query:
   > ...
   > produces the following error:
   > ERROR:  wrong varnullingrels (b) (expected (b 4)) for Var 2/1
   
   Thanks for the clear report!  We've seen a few variants of this,
   and apparently yours is among the cases that are recently fixed.
   Trying this example on a fresh 16-tip build (more or less 16.7)
   just emits
   
   DO
   
   			regards, tom lane
   
   
   
   

3. Re: BUG #18803: ERROR: wrong varnullingrels (b) (expected (b 4)) for Var 2/1

   Marko Tiikkaja <marko@joh.to> — 2025-02-11T20:55:32Z

   Hi Tom,
   
   On Tue, Feb 11, 2025 at 5:33 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
   > Thanks for the clear report!  We've seen a few variants of this,
   > and apparently yours is among the cases that are recently fixed.
   > Trying this example on a fresh 16-tip build (more or less 16.7)
   > just emits
   
   That would be my bad.  I git grep'd the 16 branch but I thought it was
   unrelated.  Thanks for the confirmation!
   
   
   .m