drop extension if exists pg_query_rewrite;
--
create extension pg_query_rewrite;
select pgqr_truncate_rule();
 pgqr_truncate_rule 
--------------------
 t
(1 row)

--
--
drop table if exists t;
create table t(i int);
--
drop function if exists fs(in int, out int);
NOTICE:  function fs(pg_catalog.int4) does not exist, skipping
create function fs(IN p int, OUT i int) returns int as $$
begin
    insert into t(i) values (fs.p) returning t.i into fs.i;
end$$
language plpgsql;
--
select fs(1);
 fs 
----
  1
(1 row)

select * from t;
 i 
---
 1
(1 row)

select pgqr_rules();
                       pgqr_rules                       
--------------------------------------------------------
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
(10 rows)

--
select pgqr_add_rule('insert into t(i) values (fs.p) returning t.i', 'insert into t(i) values(2) returning t.i');
 pgqr_add_rule 
---------------
 t
(1 row)

--
drop function fs(in int, out int);
create function fs(IN p int, OUT i int) returns int as $$
begin
    insert into t(i) values (fs.p) returning t.i into fs.i;
end$$
language plpgsql;
--
select fs(1);
 fs 
----
  2
(1 row)

select * from t;
 i 
---
 1
 2
(2 rows)

select pgqr_rules();
                                                                      pgqr_rules                                                                      
------------------------------------------------------------------------------------------------------------------------------------------------------
 (datname=contrib_regression,"source=insert into t(i) values (fs.p) returning t.i","target=insert into t(i) values(2) returning t.i",rewrite_count=1)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
(10 rows)

--
--
--
truncate table t;
select fs(1);
 fs 
----
  2
(1 row)

select * from t;
 i 
---
 2
(1 row)

--
drop function if exists fd(in int, out int);
NOTICE:  function fd(pg_catalog.int4) does not exist, skipping
create function fd(IN p int, OUT i int) returns int as $$
begin
    execute 'select count(*) from t where i = ' || p into fd.i using fd.p;
end$$
language plpgsql;
--
select fd(2);
 fd 
----
  1
(1 row)

select * from t;
 i 
---
 2
(1 row)

select pgqr_rules();
                                                                      pgqr_rules                                                                      
------------------------------------------------------------------------------------------------------------------------------------------------------
 (datname=contrib_regression,"source=insert into t(i) values (fs.p) returning t.i","target=insert into t(i) values(2) returning t.i",rewrite_count=2)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
(10 rows)

--
select pgqr_add_rule('select count(*) from t where i = 2', 'select count(*) from t where i = 3');
 pgqr_add_rule 
---------------
 t
(1 row)

--
select fd(2);
 fd 
----
  0
(1 row)

select * from t;
 i 
---
 2
(1 row)

select pgqr_rules();
                                                                      pgqr_rules                                                                      
------------------------------------------------------------------------------------------------------------------------------------------------------
 (datname=contrib_regression,"source=insert into t(i) values (fs.p) returning t.i","target=insert into t(i) values(2) returning t.i",rewrite_count=2)
 (datname=contrib_regression,"source=select count(*) from t where i = 2","target=select count(*) from t where i = 3",rewrite_count=1)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
 (datname=NULL,source=NULL,target=NULL,rewrite_count=0)
(10 rows)