... and here is a review for patch 4

I didn't change any code, just added the odd article to a comment.

While running the regression tests with "make installcheck", I noticed two problems:

  --- /home/laurenz/postgresql/src/test/regress/expected/session_variables.out    2024-10-24 11:14:06.717663613 +0300
  +++ /home/laurenz/postgresql/src/test/regress/results/session_variables.out 2024-10-24 11:15:37.999286228 +0300
  @@ -30,6 +30,7 @@
   GRANT ALL ON SCHEMA svartest TO regress_variable_owner;
   CREATE VARIABLE svartest.var1 AS int;
   CREATE ROLE regress_variable_reader;
  +ERROR:  role "regress_variable_reader" already exists

I suggest that patch 0001 should drop role "regress_variable_reader" again.

  @@ -107,7 +108,7 @@
   CONTEXT:  SQL function "sqlfx" statement 1
   SELECT plpgsqlfx(20);
   ERROR:  permission denied for session variable var1
  -CONTEXT:  SQL expression "$1 + var1"
  +CONTEXT:  PL/pgSQL expression "$1 + var1"

That looks like bit rot from your commit 4af123ad45.

Yours,
Laurenz Albe