Generated columns

This is an SQL-standard feature that allows creating columns that are
computed from expressions rather than assigned, similar to a view or
materialized view but on a column basis.

This implements one kind of generated column: stored (computed on
write).  Another kind, virtual (computed on read), is planned for the
future, and some room is left for it.

Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/b151f851-4019-bdb1-699e-ebab07d2f40a@2ndquadrant.com

1 files changed, 14 insertions, 0 deletions

diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 4728511abf3..a96c3271348 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -1364,6 +1364,20 @@ select * from loc1;
 select * from rem1;
 
 -- ===================================================================
+-- test generated columns
+-- ===================================================================
+create table gloc1 (a int, b int);
+alter table gloc1 set (autovacuum_enabled = 'false');
+create foreign table grem1 (
+  a int,
+  b int generated always as (a * 2) stored)
+  server loopback options(table_name 'gloc1');
+insert into grem1 (a) values (1), (2);
+update grem1 set a = 22 where a = 2;
+select * from gloc1;
+select * from grem1;
+
+-- ===================================================================
 -- test local triggers
 -- ===================================================================