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-- 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) stored,
m 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,
-- The same for stored expression.
l int,
-- Override the value computed on the source table.
m 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;
i | j | k | l | m
---+---+---+---+---
1 | 0 | 2 | 2 | 0
(1 row)
CREATE EXTENSION pageinspect;
-- HEAP_HASNULL indicates that the value of 'm' 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)
-- For PG < 18, test without VIRTUAL columns.
CREATE TABLE tab8(
i int primary key,
j int,
k int generated always AS (i + 1) stored);
CREATE TABLE tab8_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);
INSERT INTO tab8(i, j) VALUES (1, 1);
SELECT rewrite_table('tab8', 'tab8_new', 'tab8_orig');
rewrite_table
---------------
(1 row)
SELECT * FROM tab8;
i | j | k
---+---+---
1 | 0 | 2
(1 row)
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