Implement handling of generated columns.

Author: Antonin Houska

expected/pg_rewrite.out

@@ -379,3 +379,43 @@ SELECT i FROM tab6 ORDER BY i;
  2
 (2 rows)
 
+-- Generated columns - some meaningful combinations of source and destination
+-- columns.
+CREATE TABLE tab7(
+        i int primary key,
+	j int,
+	k int generated always as (i + 1) virtual,
+	l int generated always AS (i + 1) virtual);
+CREATE TABLE tab7_new(
+        i int primary key,
+        -- Override the value copied from the source table.
+        j int generated always AS (i - 1) stored,
+	-- Check that the expression is evaluated correctly on the source
+	-- table.
+	k int,
+	-- Override the value computed on the source table.
+	l int generated always as (i - 1) virtual);
+INSERT INTO tab7(i, j) VALUES (1, 1);
+SELECT rewrite_table('tab7', 'tab7_new', 'tab7_orig');
+ rewrite_table 
+---------------
+ 
+(1 row)
+
+SELECT * FROM tab7 ORDER BY i;
+ i | j | k | l 
+---+---+---+---
+ 1 | 0 | 2 | 0
+(1 row)
+
+CREATE EXTENSION pageinspect;
+-- HEAP_HASNULL indicates that the value of 'l' hasn't been copied from the
+-- source table.
+SELECT raw_flags
+FROM heap_page_items(get_raw_page('tab7', 0)),
+LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2);
+                      raw_flags                       
+------------------------------------------------------
+ {HEAP_HASNULL,HEAP_XMIN_COMMITTED,HEAP_XMAX_INVALID}
+(1 row)
+

expected/pg_rewrite_concurrent.out

@@ -80,20 +80,20 @@ $$;
 step do_check: 
     TABLE pg_rewrite_progress;
 
-    SELECT i, j FROM tbl_src ORDER BY i, j;
+    SELECT i, j, k, l FROM tbl_src ORDER BY i, j;
 
 src_table|dst_table|src_table_new|ins_initial|ins|upd|del
 ---------+---------+-------------+-----------+---+---+---
 tbl_src  |tbl_dst  |tbl_src_old  |          3|  3|  4|  1
 (1 row)
 
-i| j
--+--
-1| 0
-2| 8
-3|30
-5|50
-6|40
+i| j|  k|  l
+-+--+---+---
+1| 0|  0|  0
+2| 8| -8| -8
+3|30|-30|-30
+5|50|-50|-50
+6|40|-40|-40
 (5 rows)
 
 step wakeup_after_commit_ip: