Add a way to get the current function's OID in pl/pgsql.

Invent "GET DIAGNOSTICS oid_variable = PG_ROUTINE_OID".
This is useful for avoiding the maintenance nuisances that come
with embedding a function's name in its body, as one might do
for logging purposes for example.  Typically users would cast the
result to regproc or regprocedure to get something human-readable,
but we won't pre-judge whether that's appropriate.

Pavel Stehule, reviewed by Kirk Wolak and myself

Discussion: https://postgr.es/m/CAFj8pRA4zMd5pY-B89Gm64bDLRt-L+akOd34aD1j4PEstHHSVQ@mail.gmail.com

2 files changed, 56 insertions, 4 deletions

diff --git a/src/test/regress/expected/plpgsql.out b/src/test/regress/expected/plpgsql.out
index 2d26be1a81..272f5d2111 100644
--- a/src/test/regress/expected/plpgsql.out
+++ b/src/test/regress/expected/plpgsql.out
@@ -5229,7 +5229,7 @@ NOTICE:  outer_func() done
                20
 (1 row)
 
--- repeated call should to work
+-- repeated call should work
 select outer_outer_func(20);
 NOTICE:  calling down into outer_func()
 NOTICE:  calling down into inner_func()
@@ -5311,7 +5311,7 @@ NOTICE:  outer_func() done
                20
 (1 row)
 
--- repeated call should to work
+-- repeated call should work
 select outer_outer_func(20);
 NOTICE:  calling down into outer_func()
 NOTICE:  calling down into inner_func()
@@ -5332,6 +5332,33 @@ NOTICE:  outer_func() done
 drop function outer_outer_func(int);
 drop function outer_func(int);
 drop function inner_func(int);
+-- Test pg_routine_oid
+create function current_function(text)
+returns regprocedure as $$
+declare
+  fn_oid regprocedure;
+begin
+  get diagnostics fn_oid = pg_routine_oid;
+  return fn_oid;
+end;
+$$ language plpgsql;
+select current_function('foo');
+    current_function    
+------------------------
+ current_function(text)
+(1 row)
+
+drop function current_function(text);
+-- shouldn't fail in DO, even though there's no useful data
+do $$
+declare
+  fn_oid oid;
+begin
+  get diagnostics fn_oid = pg_routine_oid;
+  raise notice 'pg_routine_oid = %', fn_oid;
+end;
+$$;
+NOTICE:  pg_routine_oid = 0
 --
 -- Test ASSERT
 --
diff --git a/src/test/regress/sql/plpgsql.sql b/src/test/regress/sql/plpgsql.sql
index 98365e087f..924d524094 100644
--- a/src/test/regress/sql/plpgsql.sql
+++ b/src/test/regress/sql/plpgsql.sql
@@ -4206,7 +4206,7 @@ end;
 $$ language plpgsql;
 
 select outer_outer_func(10);
--- repeated call should to work
+-- repeated call should work
 select outer_outer_func(20);
 
 drop function outer_outer_func(int);
@@ -4261,13 +4261,38 @@ end;
 $$ language plpgsql;
 
 select outer_outer_func(10);
--- repeated call should to work
+-- repeated call should work
 select outer_outer_func(20);
 
 drop function outer_outer_func(int);
 drop function outer_func(int);
 drop function inner_func(int);
 
+-- Test pg_routine_oid
+create function current_function(text)
+returns regprocedure as $$
+declare
+  fn_oid regprocedure;
+begin
+  get diagnostics fn_oid = pg_routine_oid;
+  return fn_oid;
+end;
+$$ language plpgsql;
+
+select current_function('foo');
+
+drop function current_function(text);
+
+-- shouldn't fail in DO, even though there's no useful data
+do $$
+declare
+  fn_oid oid;
+begin
+  get diagnostics fn_oid = pg_routine_oid;
+  raise notice 'pg_routine_oid = %', fn_oid;
+end;
+$$;
+
 --
 -- Test ASSERT
 --