Ensure that pg_get_ruledef()'s output matches pg_get_viewdef()'s.

Various cases involving renaming of view columns are handled by having
make_viewdef pass down the view's current relation tupledesc to
get_query_def, which then takes care to use the column names from the
tupledesc for the output column names of the SELECT.  For some reason
though, we'd missed teaching make_ruledef to do similarly when it is
printing an ON SELECT rule, even though this is exactly the same case.
The results from pg_get_ruledef would then be different and arguably wrong.
In particular, this breaks pre-v10 versions of pg_dump, which in some
situations would define views by means of emitting a CREATE RULE ... ON
SELECT command.  Third-party tools might not be happy either.

In passing, clean up some crufty code in make_viewdef; we'd apparently
modernized the equivalent code in make_ruledef somewhere along the way,
and missed this copy.

Per report from Gilles Darold.  Back-patch to all supported versions.

Discussion: https://postgr.es/m/ec05659a-40ff-4510-fc45-ca9d965d0838@dalibo.com

2 files changed, 40 insertions, 0 deletions

diff --git a/src/test/regress/expected/create_view.out b/src/test/regress/expected/create_view.out
index bec06276509..e9a017fecb4 100644
--- a/src/test/regress/expected/create_view.out
+++ b/src/test/regress/expected/create_view.out
@@ -1619,6 +1619,35 @@ select pg_get_viewdef('tt22v', true);
       LEFT JOIN tt6 ON TRUE;
 (1 row)
 
+-- check handling of views with immediately-renamed columns
+create view tt23v (col_a, col_b) as
+select q1 as other_name1, q2 as other_name2 from int8_tbl
+union
+select 42, 43;
+select pg_get_viewdef('tt23v', true);
+        pg_get_viewdef         
+-------------------------------
+  SELECT int8_tbl.q1 AS col_a,+
+     int8_tbl.q2 AS col_b     +
+    FROM int8_tbl             +
+ UNION                        +
+  SELECT 42 AS col_a,         +
+     43 AS col_b;
+(1 row)
+
+select pg_get_ruledef(oid, true) from pg_rewrite
+  where ev_class = 'tt23v'::regclass and ev_type = '1';
+                         pg_get_ruledef                          
+-----------------------------------------------------------------
+ CREATE RULE "_RETURN" AS                                       +
+     ON SELECT TO tt23v DO INSTEAD  SELECT int8_tbl.q1 AS col_a,+
+     int8_tbl.q2 AS col_b                                       +
+    FROM int8_tbl                                               +
+ UNION                                                          +
+  SELECT 42 AS col_a,                                           +
+     43 AS col_b;
+(1 row)
+
 -- clean up all the random objects we made above
 set client_min_messages = warning;
 DROP SCHEMA temp_view_test CASCADE;
diff --git a/src/test/regress/sql/create_view.sql b/src/test/regress/sql/create_view.sql
index 2246bade46c..8a365749fce 100644
--- a/src/test/regress/sql/create_view.sql
+++ b/src/test/regress/sql/create_view.sql
@@ -541,6 +541,17 @@ create view tt22v as
 select * from tt5 natural left join tt6;
 select pg_get_viewdef('tt22v', true);
 
+-- check handling of views with immediately-renamed columns
+
+create view tt23v (col_a, col_b) as
+select q1 as other_name1, q2 as other_name2 from int8_tbl
+union
+select 42, 43;
+
+select pg_get_viewdef('tt23v', true);
+select pg_get_ruledef(oid, true) from pg_rewrite
+  where ev_class = 'tt23v'::regclass and ev_type = '1';
+
 -- clean up all the random objects we made above
 set client_min_messages = warning;
 DROP SCHEMA temp_view_test CASCADE;