Subject: Re: Virtual generated columns

From: Peter Eisentraut <[email-masked]>
Date: Wed, 22 May 2024 19:22:47 +0200

On 29.04.24 10:23, Peter Eisentraut wrote:
> Here is a patch set to implement virtual generated columns.

> The main feature patch (0005 here) generally works but has a number of 
> open corner cases that need to be thought about and/or fixed, many of 
> which are marked in the code or the tests.  I'll continue working on 
> that.  But I wanted to see if I can get some feedback on the test 
> structure, so I don't have to keep changing it around later.

Here is an updated patch set.  It needed some rebasing, especially 
around the reverting of the catalogued not-null constraints.  I have 
also fixed up the various incomplete or "fixme" pieces of code mentioned 
above.  I have in most cases added "not supported yet" error messages 
for now, with the idea that some of these things can be added in later, 
as incremental features.

In particular, quoting from the commit message, the following are 
currently not supported (but could possibly be added as incremental 
features, some easier than others):

- index on virtual column
- expression index using a virtual column
- hence also no unique constraints on virtual columns
- not-null constraints on virtual columns
- (check constraints are supported)
- foreign key constraints on virtual columns
- extended statistics on virtual columns
- ALTER TABLE / SET EXPRESSION
- ALTER TABLE / DROP EXPRESSION
- virtual columns as trigger columns
- virtual column cannot have domain type

So, I think this basically works now, and the things that don't work 
should be appropriately prevented.  So if someone wants to test this and 
tell me what in fact doesn't work correctly, that would be helpful.
From 1df68f38a7160fff4e48821c3a0419882a2d2523 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <[email-masked]>
Date: Mon, 29 Apr 2024 09:46:43 +0200
Subject: [PATCH v1 1/5] Rename regress test generated to generated_stored

This makes naming room to have another test file for virtual generated
columns.
---
 .../regress/expected/{generated.out => generated_stored.out}    | 0
 src/test/regress/parallel_schedule                              | 2 +-
 src/test/regress/sql/{generated.sql => generated_stored.sql}    | 0
 3 files changed, 1 insertion(+), 1 deletion(-)
 rename src/test/regress/expected/{generated.out => generated_stored.out} (100%)
 rename src/test/regress/sql/{generated.sql => generated_stored.sql} (100%)

diff --git a/src/test/regress/expected/generated.out b/src/test/regress/expected/generated_stored.out
similarity index 100%
rename from src/test/regress/expected/generated.out
rename to src/test/regress/expected/generated_stored.out
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 969ced994f4..d4bbc0db25b 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -66,7 +66,7 @@ test: select_into select_distinct select_distinct_on select_implicit select_havi
 # ----------
 # Another group of parallel tests
 # ----------
-test: brin gin gist spgist privileges init_privs security_label collate matview lock replica_identity rowsecurity object_address tablesample groupingsets drop_operator password identity generated join_hash
+test: brin gin gist spgist privileges init_privs security_label collate matview lock replica_identity rowsecurity object_address tablesample groupingsets drop_operator password identity generated_stored join_hash
 
 # ----------
 # Additional BRIN tests
diff --git a/src/test/regress/sql/generated.sql b/src/test/regress/sql/generated_stored.sql
similarity index 100%
rename from src/test/regress/sql/generated.sql
rename to src/test/regress/sql/generated_stored.sql

base-commit: c37267162e889fe783786b9e28d1b65b82365a00
-- 
2.44.0

From 313544d8ea4ba22433bbb9501a0252262c916ffc Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <[email-masked]>
Date: Mon, 29 Apr 2024 09:46:43 +0200
Subject: [PATCH v1 2/5] Put generated_stored test objects in a schema

This avoids naming conflicts with concurrent tests with similarly
named objects.  Currently, there are none, but a tests for virtual
generated columns are planned to be added.
---
 .../regress/expected/generated_stored.out     | 71 ++++++++++---------
 src/test/regress/sql/generated_stored.sql     |  8 ++-
 2 files changed, 43 insertions(+), 36 deletions(-)

diff --git a/src/test/regress/expected/generated_stored.out b/src/test/regress/expected/generated_stored.out
index 44058db7c1d..dd74a1a9f0b 100644
--- a/src/test/regress/expected/generated_stored.out
+++ b/src/test/regress/expected/generated_stored.out
@@ -4,9 +4,12 @@ SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT
 ----------+---------+--------------
 (0 rows)
 
+CREATE SCHEMA generated_stored_tests;
+GRANT USAGE ON SCHEMA generated_stored_tests TO PUBLIC;
+SET search_path = generated_stored_tests;
 CREATE TABLE gtest0 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (55) STORED);
 CREATE TABLE gtest1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
-SELECT table_name, column_name, column_default, is_nullable, is_generated, generation_expression FROM information_schema.columns WHERE table_name LIKE 'gtest_' ORDER BY 1, 2;
+SELECT table_name, column_name, column_default, is_nullable, is_generated, generation_expression FROM information_schema.columns WHERE table_schema = 'generated_stored_tests' ORDER BY 1, 2;
  table_name | column_name | column_default | is_nullable | is_generated | generation_expression 
 ------------+-------------+----------------+-------------+--------------+-----------------------
  gtest0     | a           |                | NO          | NEVER        | 
@@ -15,14 +18,14 @@ SELECT table_name, column_name, column_default, is_nullable, is_generated, gener
  gtest1     | b           |                | YES         | ALWAYS       | (a * 2)
 (4 rows)
 
-SELECT table_name, column_name, dependent_column FROM information_schema.column_column_usage ORDER BY 1, 2, 3;
+SELECT table_name, column_name, dependent_column FROM information_schema.column_column_usage WHERE table_schema = 'generated_stored_tests' ORDER BY 1, 2, 3;
  table_name | column_name | dependent_column 
 ------------+-------------+------------------
  gtest1     | a           | b
 (1 row)
 
 \d gtest1
-                            Table "public.gtest1"
+                    Table "generated_stored_tests.gtest1"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           | not null | 
@@ -270,7 +273,7 @@ SELECT * FROM gtest1_1;
 (0 rows)
 
 \d gtest1_1
-                           Table "public.gtest1_1"
+                   Table "generated_stored_tests.gtest1_1"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           | not null | 
@@ -312,7 +315,7 @@ ERROR:  column "b" inherits from generated column but specifies identity
 CREATE TABLE gtestx (x int, b int GENERATED ALWAYS AS (a * 22) STORED) INHERITS (gtest1);  -- ok, overrides parent
 NOTICE:  merging column "b" with inherited definition
 \d+ gtestx
-                                                Table "public.gtestx"
+                                        Table "generated_stored_tests.gtestx"
  Column |  Type   | Collation | Nullable |               Default               | Storage | Stats target | Description 
 --------+---------+-----------+----------+-------------------------------------+---------+--------------+-------------
  a      | integer |           | not null |                                     | plain   |              | 
@@ -348,7 +351,7 @@ NOTICE:  merging multiple inherited definitions of column "b"
 NOTICE:  moving and merging column "b" with inherited definition
 DETAIL:  User-specified column moved to the position of the inherited column.
 \d gtest1_y
-                           Table "public.gtest1_y"
+                   Table "generated_stored_tests.gtest1_y"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           | not null | 
@@ -523,7 +526,7 @@ HINT:  Use DROP ... CASCADE to drop the dependent objects too.
 ALTER TABLE gtest10 DROP COLUMN b CASCADE;  -- drops c too
 NOTICE:  drop cascades to column c of table gtest10
 \d gtest10
-              Table "public.gtest10"
+      Table "generated_stored_tests.gtest10"
  Column |  Type   | Collation | Nullable | Default 
 --------+---------+-----------+----------+---------
  a      | integer |           | not null | 
@@ -622,7 +625,7 @@ CREATE INDEX gtest22c_b_idx ON gtest22c (b);
 CREATE INDEX gtest22c_expr_idx ON gtest22c ((b * 3));
 CREATE INDEX gtest22c_pred_idx ON gtest22c (a) WHERE b > 0;
 \d gtest22c
-                           Table "public.gtest22c"
+                   Table "generated_stored_tests.gtest22c"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           |          | 
@@ -726,7 +729,7 @@ CREATE TABLE gtest23x (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STOR
 ERROR:  invalid ON DELETE action for foreign key constraint containing generated column
 CREATE TABLE gtest23b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED REFERENCES gtest23a (x));
 \d gtest23b
-                           Table "public.gtest23b"
+                   Table "generated_stored_tests.gtest23b"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           | not null | 
@@ -805,7 +808,7 @@ DROP TABLE gtest_child3;
 CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 33) STORED);
 ALTER TABLE gtest_parent ATTACH PARTITION gtest_child3 FOR VALUES FROM ('2016-09-01') TO ('2016-10-01');
 \d gtest_child
-                          Table "public.gtest_child"
+                  Table "generated_stored_tests.gtest_child"
  Column |  Type  | Collation | Nullable |               Default               
 --------+--------+-----------+----------+-------------------------------------
  f1     | date   |           | not null | 
@@ -814,7 +817,7 @@ ALTER TABLE gtest_parent ATTACH PARTITION gtest_child3 FOR VALUES FROM ('2016-09
 Partition of: gtest_parent FOR VALUES FROM ('07-01-2016') TO ('08-01-2016')
 
 \d gtest_child2
-                          Table "public.gtest_child2"
+                  Table "generated_stored_tests.gtest_child2"
  Column |  Type  | Collation | Nullable |               Default                
 --------+--------+-----------+----------+--------------------------------------
  f1     | date   |           | not null | 
@@ -823,7 +826,7 @@ Partition of: gtest_parent FOR VALUES FROM ('07-01-2016') TO ('08-01-2016')
 Partition of: gtest_parent FOR VALUES FROM ('08-01-2016') TO ('09-01-2016')
 
 \d gtest_child3
-                          Table "public.gtest_child3"
+                  Table "generated_stored_tests.gtest_child3"
  Column |  Type  | Collation | Nullable |               Default                
 --------+--------+-----------+----------+--------------------------------------
  f1     | date   |           | not null | 
@@ -855,7 +858,7 @@ SELECT tableoid::regclass, * FROM gtest_parent ORDER BY 1, 2, 3;
 ALTER TABLE ONLY gtest_parent ALTER COLUMN f3 SET EXPRESSION AS (f2 * 4);
 ALTER TABLE gtest_child ALTER COLUMN f3 SET EXPRESSION AS (f2 * 10);
 \d gtest_parent
-                   Partitioned table "public.gtest_parent"
+           Partitioned table "generated_stored_tests.gtest_parent"
  Column |  Type  | Collation | Nullable |               Default               
 --------+--------+-----------+----------+-------------------------------------
  f1     | date   |           | not null | 
@@ -865,7 +868,7 @@ Partition key: RANGE (f1)
 Number of partitions: 3 (Use \d+ to list them.)
 
 \d gtest_child
-                          Table "public.gtest_child"
+                  Table "generated_stored_tests.gtest_child"
  Column |  Type  | Collation | Nullable |               Default                
 --------+--------+-----------+----------+--------------------------------------
  f1     | date   |           | not null | 
@@ -874,7 +877,7 @@ Number of partitions: 3 (Use \d+ to list them.)
 Partition of: gtest_parent FOR VALUES FROM ('07-01-2016') TO ('08-01-2016')
 
 \d gtest_child2
-                          Table "public.gtest_child2"
+                  Table "generated_stored_tests.gtest_child2"
  Column |  Type  | Collation | Nullable |               Default                
 --------+--------+-----------+----------+--------------------------------------
  f1     | date   |           | not null | 
@@ -883,7 +886,7 @@ Partition of: gtest_parent FOR VALUES FROM ('07-01-2016') TO ('08-01-2016')
 Partition of: gtest_parent FOR VALUES FROM ('08-01-2016') TO ('09-01-2016')
 
 \d gtest_child3
-                          Table "public.gtest_child3"
+                  Table "generated_stored_tests.gtest_child3"
  Column |  Type  | Collation | Nullable |               Default                
 --------+--------+-----------+----------+--------------------------------------
  f1     | date   |           | not null | 
@@ -902,7 +905,7 @@ SELECT tableoid::regclass, * FROM gtest_parent ORDER BY 1, 2, 3;
 -- alter generation expression of parent and all its children altogether
 ALTER TABLE gtest_parent ALTER COLUMN f3 SET EXPRESSION AS (f2 * 2);
 \d gtest_parent
-                   Partitioned table "public.gtest_parent"
+           Partitioned table "generated_stored_tests.gtest_parent"
  Column |  Type  | Collation | Nullable |               Default               
 --------+--------+-----------+----------+-------------------------------------
  f1     | date   |           | not null | 
@@ -912,7 +915,7 @@ Partition key: RANGE (f1)
 Number of partitions: 3 (Use \d+ to list them.)
 
 \d gtest_child
-                          Table "public.gtest_child"
+                  Table "generated_stored_tests.gtest_child"
  Column |  Type  | Collation | Nullable |               Default               
 --------+--------+-----------+----------+-------------------------------------
  f1     | date   |           | not null | 
@@ -921,7 +924,7 @@ Number of partitions: 3 (Use \d+ to list them.)
 Partition of: gtest_parent FOR VALUES FROM ('07-01-2016') TO ('08-01-2016')
 
 \d gtest_child2
-                         Table "public.gtest_child2"
+                 Table "generated_stored_tests.gtest_child2"
  Column |  Type  | Collation | Nullable |               Default               
 --------+--------+-----------+----------+-------------------------------------
  f1     | date   |           | not null | 
@@ -930,7 +933,7 @@ Partition of: gtest_parent FOR VALUES FROM ('07-01-2016') TO ('08-01-2016')
 Partition of: gtest_parent FOR VALUES FROM ('08-01-2016') TO ('09-01-2016')
 
 \d gtest_child3
-                         Table "public.gtest_child3"
+                 Table "generated_stored_tests.gtest_child3"
  Column |  Type  | Collation | Nullable |               Default               
 --------+--------+-----------+----------+-------------------------------------
  f1     | date   |           | not null | 
@@ -987,7 +990,7 @@ SELECT * FROM gtest25 ORDER BY a;
 (2 rows)
 
 \d gtest25
-                                         Table "public.gtest25"
+                                 Table "generated_stored_tests.gtest25"
  Column |       Type       | Collation | Nullable |                       Default                        
 --------+------------------+-----------+----------+------------------------------------------------------
  a      | integer          |           | not null | 
@@ -1011,7 +1014,7 @@ ERROR:  cannot alter type of a column used by a generated column
 DETAIL:  Column "a" is used by generated column "x".
 ALTER TABLE gtest27 ALTER COLUMN x TYPE numeric;
 \d gtest27
-                                Table "public.gtest27"
+                        Table "generated_stored_tests.gtest27"
  Column |  Type   | Collation | Nullable |                  Default                   
 --------+---------+-----------+----------+--------------------------------------------
  a      | integer |           |          | 
@@ -1037,7 +1040,7 @@ ALTER TABLE gtest27
   ALTER COLUMN b TYPE bigint,
   ADD COLUMN x bigint GENERATED ALWAYS AS ((a + b) * 2) STORED;
 \d gtest27
-                              Table "public.gtest27"
+                      Table "generated_stored_tests.gtest27"
  Column |  Type  | Collation | Nullable |                 Default                  
 --------+--------+-----------+----------+------------------------------------------
  a      | bigint |           |          | 
@@ -1051,7 +1054,7 @@ ALTER TABLE gtest27
 ERROR:  cannot alter type of a column used by a generated column
 DETAIL:  Column "a" is used by generated column "x".
 \d gtest27
-                              Table "public.gtest27"
+                      Table "generated_stored_tests.gtest27"
  Column |  Type  | Collation | Nullable |                 Default                  
 --------+--------+-----------+----------+------------------------------------------
  a      | bigint |           |          | 
@@ -1079,7 +1082,7 @@ SELECT * FROM gtest29;
 (2 rows)
 
 \d gtest29
-                            Table "public.gtest29"
+                    Table "generated_stored_tests.gtest29"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           |          | 
@@ -1101,7 +1104,7 @@ SELECT * FROM gtest29;
 (2 rows)
 
 \d gtest29
-                            Table "public.gtest29"
+                    Table "generated_stored_tests.gtest29"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           |          | 
@@ -1120,7 +1123,7 @@ SELECT * FROM gtest29;
 (4 rows)
 
 \d gtest29
-              Table "public.gtest29"
+      Table "generated_stored_tests.gtest29"
  Column |  Type   | Collation | Nullable | Default 
 --------+---------+-----------+----------+---------
  a      | integer |           |          | 
@@ -1129,7 +1132,7 @@ SELECT * FROM gtest29;
 -- check that dependencies between columns have also been removed
 ALTER TABLE gtest29 DROP COLUMN a;  -- should not drop b
 \d gtest29
-              Table "public.gtest29"
+      Table "generated_stored_tests.gtest29"
  Column |  Type   | Collation | Nullable | Default 
 --------+---------+-----------+----------+---------
  b      | integer |           |          | 
@@ -1142,7 +1145,7 @@ CREATE TABLE gtest30 (
 CREATE TABLE gtest30_1 () INHERITS (gtest30);
 ALTER TABLE gtest30 ALTER COLUMN b DROP EXPRESSION;
 \d gtest30
-              Table "public.gtest30"
+      Table "generated_stored_tests.gtest30"
  Column |  Type   | Collation | Nullable | Default 
 --------+---------+-----------+----------+---------
  a      | integer |           |          | 
@@ -1150,7 +1153,7 @@ ALTER TABLE gtest30 ALTER COLUMN b DROP EXPRESSION;
 Number of child tables: 1 (Use \d+ to list them.)
 
 \d gtest30_1
-             Table "public.gtest30_1"
+     Table "generated_stored_tests.gtest30_1"
  Column |  Type   | Collation | Nullable | Default 
 --------+---------+-----------+----------+---------
  a      | integer |           |          | 
@@ -1167,7 +1170,7 @@ CREATE TABLE gtest30_1 () INHERITS (gtest30);
 ALTER TABLE ONLY gtest30 ALTER COLUMN b DROP EXPRESSION;  -- error
 ERROR:  ALTER TABLE / DROP EXPRESSION must be applied to child tables too
 \d gtest30
-                            Table "public.gtest30"
+                    Table "generated_stored_tests.gtest30"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           |          | 
@@ -1175,7 +1178,7 @@ ERROR:  ALTER TABLE / DROP EXPRESSION must be applied to child tables too
 Number of child tables: 1 (Use \d+ to list them.)
 
 \d gtest30_1
-                           Table "public.gtest30_1"
+                   Table "generated_stored_tests.gtest30_1"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           |          | 
@@ -1336,14 +1339,14 @@ CREATE TABLE gtest28a (
 ALTER TABLE gtest28a DROP COLUMN a;
 CREATE TABLE gtest28b (LIKE gtest28a INCLUDING GENERATED);
 \d gtest28*
-                           Table "public.gtest28a"
+                   Table "generated_stored_tests.gtest28a"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  b      | integer |           |          | 
  c      | integer |           |          | 
  x      | integer |           |          | generated always as (b * 2) stored
 
-                           Table "public.gtest28b"
+                   Table "generated_stored_tests.gtest28b"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  b      | integer |           |          | 
diff --git a/src/test/regress/sql/generated_stored.sql b/src/test/regress/sql/generated_stored.sql
index cb55d77821f..c18e0e1f655 100644
--- a/src/test/regress/sql/generated_stored.sql
+++ b/src/test/regress/sql/generated_stored.sql
@@ -2,12 +2,16 @@
 SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT IN ('', 's');

+CREATE SCHEMA generated_stored_tests;
+GRANT USAGE ON SCHEMA generated_stored_tests TO PUBLIC;
+SET search_path = generated_stored_tests;
+
 CREATE TABLE gtest0 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (55) STORED);
 CREATE TABLE gtest1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
 
-SELECT table_name, column_name, column_default, is_nullable, is_generated, generation_expression FROM information_schema.columns WHERE table_name LIKE 'gtest_' ORDER BY 1, 2;
+SELECT table_name, column_name, column_default, is_nullable, is_generated, generation_expression FROM information_schema.columns WHERE table_schema = 'generated_stored_tests' ORDER BY 1, 2;
 
-SELECT table_name, column_name, dependent_column FROM information_schema.column_column_usage ORDER BY 1, 2, 3;
+SELECT table_name, column_name, dependent_column FROM information_schema.column_column_usage WHERE table_schema = 'generated_stored_tests' ORDER BY 1, 2, 3;
 
 \d gtest1
 
-- 
2.44.0

From 6653f72f7990488a5958451666b81c105d7f91de Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <[email-masked]>
Date: Mon, 29 Apr 2024 09:46:43 +0200
Subject: [PATCH v1 3/5] Remove useless initializations

The struct is already initialized to all zeros right before this, and
randomly initializing a few but not all fields to zero again has no
technical or educational value.
---
 src/backend/utils/cache/relcache.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index cc9b0c6524f..b09f6a90e44 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -535,8 +535,6 @@ RelationBuildTupleDesc(Relation relation)
 
 	constr = (TupleConstr *) MemoryContextAllocZero(CacheMemoryContext,
 													sizeof(TupleConstr));
-	constr->has_not_null = false;
-	constr->has_generated_stored = false;
 
 	/*
 	 * Form a scan key that selects only user attributes (attnum > 0).
-- 
2.44.0

From d2325a73711d77e5bd0bdc3df234efac229cb948 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <[email-masked]>
Date: Mon, 29 Apr 2024 09:46:44 +0200
Subject: [PATCH v1 4/5] Remove useless code

BuildDescForRelation() goes out of its way to fill in
->constr->has_not_null, but that value is not used for anything later,
so this code can all be removed.  Note that BuildDescForRelation()
doesn't make any effort to fill in the rest of ->constr, so there is
no claim that that structure is completely filled in.
---
 src/backend/commands/tablecmds.c | 25 +++----------------------
 1 file changed, 3 insertions(+), 22 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 313c782cae2..958007ca316 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -1272,7 +1272,9 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
  *
  * Given a list of ColumnDef nodes, build a TupleDesc.
  *
- * Note: tdtypeid will need to be filled in later on.
+ * Note: This is only for the limited purpose of table and view creation.  Not
+ * everything is filled in.  A real tuple descriptor should be obtained from
+ * the relcache.
  */
 TupleDesc
 BuildDescForRelation(const List *columns)
@@ -1281,7 +1283,6 @@ BuildDescForRelation(const List *columns)
 	AttrNumber	attnum;
 	ListCell   *l;
 	TupleDesc	desc;
-	bool		has_not_null;
 	char	   *attname;
 	Oid			atttypid;
 	int32		atttypmod;
@@ -1293,7 +1294,6 @@ BuildDescForRelation(const List *columns)
 	 */
 	natts = list_length(columns);
 	desc = CreateTemplateTupleDesc(natts);
-	has_not_null = false;
 
 	attnum = 0;
 
@@ -1339,7 +1339,6 @@ BuildDescForRelation(const List *columns)
 
 		/* Fill in additional stuff not handled by TupleDescInitEntry */
 		att->attnotnull = entry->is_not_null;
-		has_not_null |= entry->is_not_null;
 		att->attislocal = entry->is_local;
 		att->attinhcount = entry->inhcount;
 		att->attidentity = entry->identity;
@@ -1351,24 +1350,6 @@ BuildDescForRelation(const List *columns)
 			att->attstorage = GetAttributeStorage(att->atttypid, entry->storage_name);
 	}
 
-	if (has_not_null)
-	{
-		TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
-
-		constr->has_not_null = true;
-		constr->has_generated_stored = false;
-		constr->defval = NULL;
-		constr->missing = NULL;
-		constr->num_defval = 0;
-		constr->check = NULL;
-		constr->num_check = 0;
-		desc->constr = constr;
-	}
-	else
-	{
-		desc->constr = NULL;
-	}
-
 	return desc;
 }
 
-- 
2.44.0

From 687cb97094ba038cc4d59f1a6fb04492efaf6a46 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <[email-masked]>
Date: Wed, 22 May 2024 10:44:52 +0200
Subject: [PATCH v1 5/5] Virtual generated columns

This adds a new variant of generated columns that are computed on read
(like a view, unlike the existing stored generated columns, which are
computed on write, like a materialized view).

Some functionality is currently not supported (but could possibly be
added as incremental features, some easier than others):

- index on virtual column
- expression index using a virtual column
- hence also no unique constraints on virtual columns
- not-null constraints on virtual columns
- (check constraints are supported)
- foreign key constraints on virtual columns
- extended statistics on virtual columns
- ALTER TABLE / SET EXPRESSION
- ALTER TABLE / DROP EXPRESSION
- virtual columns as trigger columns
- virtual column cannot have domain type

TODO:
- analysis of access control
- check FDW/foreign table behavior
---
 contrib/pageinspect/expected/page.out         |  35 +
 contrib/pageinspect/sql/page.sql              |  17 +
 .../postgres_fdw/expected/postgres_fdw.out    |  81 +-
 contrib/postgres_fdw/sql/postgres_fdw.sql     |   9 +-
 doc/src/sgml/catalogs.sgml                    |   4 +-
 doc/src/sgml/ddl.sgml                         |  25 +-
 doc/src/sgml/ref/alter_table.sgml             |  14 +-
 doc/src/sgml/ref/create_foreign_table.sgml    |  11 +-
 doc/src/sgml/ref/create_table.sgml            |  22 +-
 doc/src/sgml/ref/create_trigger.sgml          |   2 +-
 doc/src/sgml/trigger.sgml                     |   4 +
 src/backend/access/common/tupdesc.c           |   3 +
 src/backend/commands/indexcmds.c              |  29 +-
 src/backend/commands/statscmds.c              |  10 +
 src/backend/commands/tablecmds.c              | 104 ++-
 src/backend/commands/trigger.c                |  48 +-
 src/backend/executor/execExprInterp.c         |   4 +
 src/backend/executor/execMain.c               |   5 +-
 src/backend/parser/analyze.c                  |   8 +
 src/backend/parser/gram.y                     |  15 +-
 src/backend/parser/parse_clause.c             |   4 +
 src/backend/parser/parse_relation.c           |   9 +-
 src/backend/parser/parse_utilcmd.c            |  40 +-
 src/backend/replication/pgoutput/pgoutput.c   |   3 +-
 src/backend/rewrite/rewriteHandler.c          | 164 +++-
 src/backend/utils/cache/partcache.c           |   3 +
 src/backend/utils/cache/relcache.c            |   2 +
 src/bin/pg_dump/pg_dump.c                     |   3 +
 src/bin/pg_dump/t/002_pg_dump.pl              |   6 +-
 src/bin/psql/describe.c                       |   6 +
 src/include/access/tupdesc.h                  |   1 +
 src/include/catalog/pg_attribute.h            |   1 +
 src/include/nodes/parsenodes.h                |   3 +
 src/include/parser/kwlist.h                   |   1 +
 src/include/parser/parse_node.h               |   1 +
 src/include/rewrite/rewriteHandler.h          |   2 +
 src/pl/plperl/expected/plperl_trigger.out     |   7 +-
 src/pl/plperl/plperl.c                        |   3 +
 src/pl/plperl/sql/plperl_trigger.sql          |   3 +-
 src/pl/plpython/expected/plpython_trigger.out |   7 +-
 src/pl/plpython/plpy_typeio.c                 |   3 +
 src/pl/plpython/sql/plpython_trigger.sql      |   3 +-
 src/pl/tcl/expected/pltcl_trigger.out         |  19 +-
 src/pl/tcl/pltcl.c                            |   3 +
 src/pl/tcl/sql/pltcl_trigger.sql              |   3 +-
 .../regress/expected/create_table_like.out    |  23 +-
 .../regress/expected/generated_stored.out     |   6 +-
 ...rated_stored.out => generated_virtual.out} | 790 ++++++++----------
 src/test/regress/parallel_schedule            |   3 +
 src/test/regress/sql/create_table_like.sql    |   2 +-
 src/test/regress/sql/generated_stored.sql     |   2 +-
 ...rated_stored.sql => generated_virtual.sql} | 280 ++++---
 src/test/subscription/t/011_generated.pl      |  38 +-
 53 files changed, 1184 insertions(+), 710 deletions(-)
 copy src/test/regress/expected/{generated_stored.out => generated_virtual.out} (70%)
 copy src/test/regress/sql/{generated_stored.sql => generated_virtual.sql} (74%)

diff --git a/contrib/pageinspect/expected/page.out b/contrib/pageinspect/expected/page.out
index 80ddb45a60a..7e0b09e279b 100644
--- a/contrib/pageinspect/expected/page.out
+++ b/contrib/pageinspect/expected/page.out
@@ -208,6 +208,41 @@ select tuple_data_split('test8'::regclass, t_data, t_infomask, t_infomask2, t_bi
 (1 row)
 
 drop table test8;
+-- check storage of generated columns
+-- stored
+create table test9s (a int not null, b int generated always as (a * 2) stored);
+insert into test9s values (131584);
+select t_infomask, t_bits, t_data from heap_page_items(get_raw_page('test9s', 0));
+ t_infomask | t_bits |       t_data       
+------------+--------+--------------------
+       2048 |        | \x0002020000040400
+(1 row)
+
+select tuple_data_split('test9s'::regclass, t_data, t_infomask, t_infomask2, t_bits)
+    from heap_page_items(get_raw_page('test9s', 0));
+       tuple_data_split        
+-------------------------------
+ {"\\x00020200","\\x00040400"}
+(1 row)
+
+drop table test9s;
+-- virtual
+create table test9v (a int not null, b int generated always as (a * 2) virtual);
+insert into test9v values (131584);
+select t_infomask, t_bits, t_data from heap_page_items(get_raw_page('test9v', 0));
+ t_infomask |  t_bits  |   t_data   
+------------+----------+------------
+       2049 | 10000000 | \x00020200
+(1 row)
+
+select tuple_data_split('test9v'::regclass, t_data, t_infomask, t_infomask2, t_bits)
+    from heap_page_items(get_raw_page('test9v', 0));
+   tuple_data_split   
+----------------------
+ {"\\x00020200",NULL}
+(1 row)
+
+drop table test9v;
 -- Failure with incorrect page size
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes.
diff --git a/contrib/pageinspect/sql/page.sql b/contrib/pageinspect/sql/page.sql
index 5bff568d3b5..186dda1e8d0 100644
--- a/contrib/pageinspect/sql/page.sql
+++ b/contrib/pageinspect/sql/page.sql
@@ -84,6 +84,23 @@ CREATE TEMP TABLE test1 (a int, b int);
     from heap_page_items(get_raw_page('test8', 0));
 drop table test8;
 
+-- check storage of generated columns
+-- stored
+create table test9s (a int not null, b int generated always as (a * 2) stored);
+insert into test9s values (131584);
+select t_infomask, t_bits, t_data from heap_page_items(get_raw_page('test9s', 0));
+select tuple_data_split('test9s'::regclass, t_data, t_infomask, t_infomask2, t_bits)
+    from heap_page_items(get_raw_page('test9s', 0));
+drop table test9s;
+
+-- virtual
+create table test9v (a int not null, b int generated always as (a * 2) virtual);
+insert into test9v values (131584);
+select t_infomask, t_bits, t_data from heap_page_items(get_raw_page('test9v', 0));
+select tuple_data_split('test9v'::regclass, t_data, t_infomask, t_infomask2, t_bits)
+    from heap_page_items(get_raw_page('test9v', 0));
+drop table test9v;
+
 -- Failure with incorrect page size
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes.
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index 078b8a966f8..7a3e71c07b4 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -7215,65 +7215,68 @@ select * from rem1;
 -- ===================================================================
 create table gloc1 (
   a int,
-  b int generated always as (a * 2) stored);
+  b int generated always as (a * 2) stored,
+  c 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');
+  b int generated always as (a * 2) stored,
+  c int generated always as (a * 3) virtual
+) server loopback options(table_name 'gloc1');
 explain (verbose, costs off)
 insert into grem1 (a) values (1), (2);
-                            QUERY PLAN                             
--------------------------------------------------------------------
+                                  QUERY PLAN                                   
+-------------------------------------------------------------------------------
  Insert on public.grem1
-   Remote SQL: INSERT INTO public.gloc1(a, b) VALUES ($1, DEFAULT)
+   Remote SQL: INSERT INTO public.gloc1(a, b, c) VALUES ($1, DEFAULT, DEFAULT)
    Batch Size: 1
    ->  Values Scan on "*VALUES*"
-         Output: "*VALUES*".column1, NULL::integer
+         Output: "*VALUES*".column1, NULL::integer, NULL::integer
 (5 rows)
 
 insert into grem1 (a) values (1), (2);
 explain (verbose, costs off)
 update grem1 set a = 22 where a = 2;
-                                     QUERY PLAN                                     
-------------------------------------------------------------------------------------
+                                       QUERY PLAN                                       
+----------------------------------------------------------------------------------------
  Update on public.grem1
-   Remote SQL: UPDATE public.gloc1 SET a = $2, b = DEFAULT WHERE ctid = $1
+   Remote SQL: UPDATE public.gloc1 SET a = $2, b = DEFAULT, c = DEFAULT WHERE ctid = $1
    ->  Foreign Scan on public.grem1
          Output: 22, ctid, grem1.*
-         Remote SQL: SELECT a, b, ctid FROM public.gloc1 WHERE ((a = 2)) FOR UPDATE
+         Remote SQL: SELECT a, b, c, ctid FROM public.gloc1 WHERE ((a = 2)) FOR UPDATE
 (5 rows)
 
 update grem1 set a = 22 where a = 2;
 select * from gloc1;
- a  | b  
-----+----
-  1 |  2
- 22 | 44
+ a  | b  | c 
+----+----+---
+  1 |  2 |  
+ 22 | 44 |  
 (2 rows)
 
 select * from grem1;
- a  | b  
-----+----
-  1 |  2
- 22 | 44
+ a  | b  | c  
+----+----+----
+  1 |  2 |  3
+ 22 | 44 | 66
 (2 rows)
 
 delete from grem1;
 -- test copy from
 copy grem1 from stdin;
 select * from gloc1;
- a | b 
----+---
- 1 | 2
- 2 | 4
+ a | b | c 
+---+---+---
+ 1 | 2 |  
+ 2 | 4 |  
 (2 rows)
 
 select * from grem1;
- a | b 
----+---
- 1 | 2
- 2 | 4
+ a | b | c 
+---+---+---
+ 1 | 2 | 3
+ 2 | 4 | 6
 (2 rows)
 
 delete from grem1;
@@ -7281,28 +7284,28 @@ delete from grem1;
 alter server loopback options (add batch_size '10');
 explain (verbose, costs off)
 insert into grem1 (a) values (1), (2);
-                            QUERY PLAN                             
--------------------------------------------------------------------
+                                  QUERY PLAN                                   
+-------------------------------------------------------------------------------
  Insert on public.grem1
-   Remote SQL: INSERT INTO public.gloc1(a, b) VALUES ($1, DEFAULT)
+   Remote SQL: INSERT INTO public.gloc1(a, b, c) VALUES ($1, DEFAULT, DEFAULT)
    Batch Size: 10
    ->  Values Scan on "*VALUES*"
-         Output: "*VALUES*".column1, NULL::integer
+         Output: "*VALUES*".column1, NULL::integer, NULL::integer
 (5 rows)
 
 insert into grem1 (a) values (1), (2);
 select * from gloc1;
- a | b 
----+---
- 1 | 2
- 2 | 4
+ a | b | c 
+---+---+---
+ 1 | 2 |  
+ 2 | 4 |  
 (2 rows)
 
 select * from grem1;
- a | b 
----+---
- 1 | 2
- 2 | 4
+ a | b | c 
+---+---+---
+ 1 | 2 | 3
+ 2 | 4 | 6
 (2 rows)
 
 delete from grem1;
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 09ba234e43d..1fc28b3e264 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -1806,12 +1806,15 @@ CREATE VIEW rw_view AS SELECT * FROM parent_tbl WHERE a < 5 WITH CHECK OPTION;
 -- ===================================================================
 create table gloc1 (
   a int,
-  b int generated always as (a * 2) stored);
+  b int generated always as (a * 2) stored,
+  c 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');
+  b int generated always as (a * 2) stored,
+  c int generated always as (a * 3) virtual
+) server loopback options(table_name 'gloc1');
 explain (verbose, costs off)
 insert into grem1 (a) values (1), (2);
 insert into grem1 (a) values (1), (2);
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 15f6255d865..839b1ddb682 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1317,8 +1317,8 @@ <title><structname>pg_attribute</structname> Columns</title>
       </para>
       <para>
        If a zero byte (<literal>''</literal>), then not a generated column.
-       Otherwise, <literal>s</literal> = stored.  (Other values might be added
-       in the future.)
+       Otherwise, <literal>s</literal> = stored, <literal>v</literal> =
+       virtual.
       </para></entry>
      </row>
 
diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index 6aab79e901c..d800f538146 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -361,7 +361,6 @@ <title>Generated Columns</title>
    storage and is computed when it is read.  Thus, a virtual generated column
    is similar to a view and a stored generated column is similar to a
    materialized view (except that it is always updated automatically).
-   <productname>PostgreSQL</productname> currently implements only stored generated columns.
   </para>
 
   <para>
@@ -371,12 +370,12 @@ <title>Generated Columns</title>
 CREATE TABLE people (
     ...,
     height_cm numeric,
-    height_in numeric <emphasis>GENERATED ALWAYS AS (height_cm / 2.54) STORED</emphasis>
+    height_in numeric <emphasis>GENERATED ALWAYS AS (height_cm / 2.54)</emphasis>
 );
 </programlisting>
-   The keyword <literal>STORED</literal> must be specified to choose the
-   stored kind of generated column.  See <xref linkend="sql-createtable"/> for
-   more details.
+   A generated column is by default of the virtual kind.  Use the keywords
+   <literal>VIRTUAL</literal> or <literal>STORED</literal> to make the choice
+   explicit.  See <xref linkend="sql-createtable"/> for more details.
   </para>
 
   <para>
@@ -442,12 +441,18 @@ <title>Generated Columns</title>
       <listitem>
        <para>
         If a parent column is a generated column, its child column must also
-        be a generated column; however, the child column can have a
-        different generation expression.  The generation expression that is
+        be a generated column of the same kind (stored or virtual); however,
+        the child column can have a different generation expression.
+       </para>
+
+       <para>
+        For stored generated columns, the generation expression that is
         actually applied during insert or update of a row is the one
-        associated with the table that the row is physically in.
-        (This is unlike the behavior for column defaults: for those, the
-        default value associated with the table named in the query applies.)
+        associated with the table that the row is physically in.  (This is
+        unlike the behavior for column defaults: for those, the default value
+        associated with the table named in the query applies.)  For virtual
+        generated columns, the generation expression of the table named in the
+        query applies when a table is read.
        </para>
       </listitem>
       <listitem>
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 5d352abf991..f89f85fb195 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -271,6 +271,11 @@ <title>Description</title>
       in the column is rewritten and all the future changes will apply the new
       generation expression.
      </para>
+
+     <para>
+      This form is currently only supported for stored generated columns (not
+      virtual ones).
+     </para>
     </listitem>
    </varlistentry>
 
@@ -283,10 +288,15 @@ <title>Description</title>
       longer apply the generation expression.
      </para>
 
+     <para>
+      This form is currently only supported for stored generated columns (not
+      virtual ones).
+     </para>
+
      <para>
       If <literal>DROP EXPRESSION IF EXISTS</literal> is specified and the
-      column is not a stored generated column, no error is thrown.  In this
-      case a notice is issued instead.
+      column is not a generated column, no error is thrown.  In this case a
+      notice is issued instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/doc/src/sgml/ref/create_foreign_table.sgml b/doc/src/sgml/ref/create_foreign_table.sgml
index dc4b9075990..21b5d6a14d0 100644
--- a/doc/src/sgml/ref/create_foreign_table.sgml
+++ b/doc/src/sgml/ref/create_foreign_table.sgml
@@ -47,7 +47,7 @@
   NULL |
   CHECK ( <replaceable class="parameter">expression</replaceable> ) [ NO INHERIT ] |
   DEFAULT <replaceable>default_expr</replaceable> |
-  GENERATED ALWAYS AS ( <replaceable>generation_expr</replaceable> ) STORED }
+  GENERATED ALWAYS AS ( <replaceable>generation_expr</replaceable> ) [ STORED | VIRTUAL ] }
 
 <phrase>and <replaceable class="parameter">table_constraint</replaceable> is:</phrase>
 
@@ -275,7 +275,7 @@ <title>Parameters</title>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>GENERATED ALWAYS AS ( <replaceable>generation_expr</replaceable> ) STORED</literal><indexterm><primary>generated column</primary></indexterm></term>
+    <term><literal>GENERATED ALWAYS AS ( <replaceable>generation_expr</replaceable> ) [ STORED | VIRTUAL ]</literal><indexterm><primary>generated column</primary></indexterm></term>
     <listitem>
      <para>
       This clause creates the column as a <firstterm>generated
@@ -284,10 +284,13 @@ <title>Parameters</title>
      </para>
 
      <para>
-      The keyword <literal>STORED</literal> is required to signify that the
+      When <literal>VIRTUAL</literal> is specified, the column will be
+      computed when it is read.  (The foreign-data wrapper will see it as a
+      null value in new rows and may choose to store it as a null value or
+      ignore it altogether.)  When <literal>STORED</literal> is specified, the
       column will be computed on write.  (The computed value will be presented
       to the foreign-data wrapper for storage and must be returned on
-      reading.)
+      reading.)  <literal>VIRTUAL</literal> is the default.
      </para>
 
      <para>
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index f19306e7760..6bca32ff383 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -65,7 +65,7 @@
   NULL |
   CHECK ( <replaceable class="parameter">expression</replaceable> ) [ NO INHERIT ] |
   DEFAULT <replaceable>default_expr</replaceable> |
-  GENERATED ALWAYS AS ( <replaceable>generation_expr</replaceable> ) STORED |
+  GENERATED ALWAYS AS ( <replaceable>generation_expr</replaceable> ) [ STORED | VIRTUAL ] |
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE [ NULLS [ NOT ] DISTINCT ] <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
@@ -720,8 +720,9 @@ <title>Parameters</title>
         <term><literal>INCLUDING GENERATED</literal></term>
         <listitem>
          <para>
-          Any generation expressions of copied column definitions will be
-          copied.  By default, new columns will be regular base columns.
+          Any generation expressions as well as the stored/virtual choice of
+          copied column definitions will be copied.  By default, new columns
+          will be regular base columns.
          </para>
         </listitem>
        </varlistentry>
@@ -897,7 +898,7 @@ <title>Parameters</title>
    </varlistentry>
 
    <varlistentry id="sql-createtable-parms-generated-stored">
-    <term><literal>GENERATED ALWAYS AS ( <replaceable>generation_expr</replaceable> ) STORED</literal><indexterm><primary>generated column</primary></indexterm></term>
+    <term><literal>GENERATED ALWAYS AS ( <replaceable>generation_expr</replaceable> ) [ STORED | VIRTUAL ]</literal><indexterm><primary>generated column</primary></indexterm></term>
     <listitem>
      <para>
       This clause creates the column as a <firstterm>generated
@@ -906,8 +907,11 @@ <title>Parameters</title>
      </para>
 
      <para>
-      The keyword <literal>STORED</literal> is required to signify that the
-      column will be computed on write and will be stored on disk.
+      When <literal>VIRTUAL</literal> is specified, the column will be
+      computed when it is read, and it will not occupy any storage.  When
+      <literal>STORED</literal> is specified, the column will be computed on
+      write and will be stored on disk.  <literal>VIRTUAL</literal> is the
+      default.
      </para>
 
      <para>
@@ -2380,9 +2384,9 @@ <title>Multiple Identity Columns</title>
    <title>Generated Columns</title>
 
    <para>
-    The option <literal>STORED</literal> is not standard but is also used by
-    other SQL implementations.  The SQL standard does not specify the storage
-    of generated columns.
+    The options <literal>STORED</literal> and <literal>VIRTUAL</literal> are
+    not standard but are also used by other SQL implementations.  The SQL
+    standard does not specify the storage of generated columns.
    </para>
   </refsect2>
 
diff --git a/doc/src/sgml/ref/create_trigger.sgml b/doc/src/sgml/ref/create_trigger.sgml
index 982ab6f3ee4..752fe50860a 100644
--- a/doc/src/sgml/ref/create_trigger.sgml
+++ b/doc/src/sgml/ref/create_trigger.sgml
@@ -279,7 +279,7 @@ <title>Parameters</title>
      <para>
       <literal>INSTEAD OF UPDATE</literal> events do not allow a list of columns.
       A column list cannot be specified when requesting transition relations,
-      either.
+      either.  Virtual generated columns are not supported in the column list.
      </para>
     </listitem>
    </varlistentry>
diff --git a/doc/src/sgml/trigger.sgml b/doc/src/sgml/trigger.sgml
index 31626536a2e..5953d24ae8f 100644
--- a/doc/src/sgml/trigger.sgml
+++ b/doc/src/sgml/trigger.sgml
@@ -289,6 +289,10 @@ <title>Overview of Trigger Behavior</title>
     <literal>BEFORE</literal> trigger.  Changes to the value of a generated
     column in a <literal>BEFORE</literal> trigger are ignored and will be
     overwritten.
+    Virtual generated columns are never computed when triggers fire.  In the C
+    language interface, their content is undefined in a trigger function.
+    Higher-level programming languages should prevent access to virtual
+    generated columns in triggers.
    </para>
 
    <para>
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 47379fef220..13840ba533c 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -190,6 +190,7 @@ CreateTupleDescCopyConstr(TupleDesc tupdesc)
 
 		cpy->has_not_null = constr->has_not_null;
 		cpy->has_generated_stored = constr->has_generated_stored;
+		cpy->has_generated_virtual = constr->has_generated_virtual;
 
 		if ((cpy->num_defval = constr->num_defval) > 0)
 		{
@@ -494,6 +495,8 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 			return false;
 		if (constr1->has_generated_stored != constr2->has_generated_stored)
 			return false;
+		if (constr1->has_generated_virtual != constr2->has_generated_virtual)
+			return false;
 		n = constr1->num_defval;
 		if (n != (int) constr2->num_defval)
 			return false;
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 309389e20d2..c7c991ad57f 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1085,6 +1085,9 @@ DefineIndex(Oid tableId,
 	/*
 	 * We disallow indexes on system columns.  They would not necessarily get
 	 * updated correctly, and they don't seem useful anyway.
+	 *
+	 * Also disallow virtual generated columns in indexes (use expression
+	 * index instead).
 	 */
 	for (int i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
 	{
@@ -1094,14 +1097,22 @@ DefineIndex(Oid tableId,
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("index creation on system columns is not supported")));
+
+
+		if (TupleDescAttr(RelationGetDescr(rel), attno - 1)->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("index creation on virtual generated columns is not supported")));
 	}
 
 	/*
-	 * Also check for system columns used in expressions or predicates.
+	 * Also check for system and generated columns used in expressions or
+	 * predicates.
 	 */
 	if (indexInfo->ii_Expressions || indexInfo->ii_Predicate)
 	{
 		Bitmapset  *indexattrs = NULL;
+		int			j;
 
 		pull_varattnos((Node *) indexInfo->ii_Expressions, 1, &indexattrs);
 		pull_varattnos((Node *) indexInfo->ii_Predicate, 1, &indexattrs);
@@ -1114,6 +1125,22 @@ DefineIndex(Oid tableId,
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 						 errmsg("index creation on system columns is not supported")));
 		}
+
+		/*
+		 * XXX Virtual generated columns in index expressions or predicates
+		 * could be supported, but it needs support in
+		 * RelationGetIndexExpressions() and RelationGetIndexPredicate().
+		 */
+		j = -1;
+		while ((j = bms_next_member(indexattrs, j)) >= 0)
+		{
+			AttrNumber	attno = j + FirstLowInvalidHeapAttributeNumber;
+
+			if (TupleDescAttr(RelationGetDescr(rel), attno - 1)->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index creation on virtual generated columns is not supported")));
+		}
 	}
 
 	/* Is index safe for others to ignore?  See set_indexsafe_procflags() */
diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
index 1db3ef69d22..fd56e472d88 100644
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -246,6 +246,11 @@ CreateStatistics(CreateStatsStmt *stmt)
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 						 errmsg("statistics creation on system columns is not supported")));
 
+			if (attForm->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("statistics creation on virtual generated columns is not supported")));
+
 			/* Disallow data types without a less-than operator */
 			type = lookup_type_cache(attForm->atttypid, TYPECACHE_LT_OPR);
 			if (type->lt_opr == InvalidOid)
@@ -269,6 +274,11 @@ CreateStatistics(CreateStatsStmt *stmt)
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 						 errmsg("statistics creation on system columns is not supported")));
 
+			if (get_attgenerated(relid, var->varattno) == ATTRIBUTE_GENERATED_VIRTUAL)
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("statistics creation on virtual generated columns is not supported")));
+
 			/* Disallow data types without a less-than operator */
 			type = lookup_type_cache(var->vartype, TYPECACHE_LT_OPR);
 			if (type->lt_opr == InvalidOid)
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 958007ca316..fa8fc3bde56 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2939,6 +2939,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 									 errhint("A child table column cannot be generated unless its parent column is.")));
 					}
 
+					if (coldef->generated && restdef->generated && coldef->generated != restdef->generated)
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
+								 errmsg("column \"%s\" inherits from generated column of different kind",
+										restdef->colname)));
+
 					/*
 					 * Override the parent's default value for this column
 					 * (coldef->cooked_default) with the partition's local
@@ -3210,6 +3216,12 @@ MergeChildAttribute(List *inh_columns, int exist_attno, int newcol_attno, const
 					 errhint("A child table column cannot be generated unless its parent column is.")));
 	}
 
+	if (inhdef->generated && newdef->generated && newdef->generated != inhdef->generated)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
+				 errmsg("column \"%s\" inherits from generated column of different kind",
+						inhdef->colname)));
+
 	/*
 	 * If new def has a default, override previous default
 	 */
@@ -5998,7 +6010,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 		{
 			case CONSTR_CHECK:
 				needscan = true;
-				con->qualstate = ExecPrepareExpr((Expr *) con->qual, estate);
+				con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, newrel ? newrel : oldrel), estate);
 				break;
 			case CONSTR_FOREIGN:
 				/* Nothing to do here */
@@ -7683,6 +7695,7 @@ ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 const char *colName, LOCKMODE lockmode)
 {
 	HeapTuple	tuple;
+	Form_pg_attribute attTup;
 	AttrNumber	attnum;
 	Relation	attr_rel;
 	ObjectAddress address;
@@ -7699,8 +7712,8 @@ ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				(errcode(ERRCODE_UNDEFINED_COLUMN),
 				 errmsg("column \"%s\" of relation \"%s\" does not exist",
 						colName, RelationGetRelationName(rel))));
-
-	attnum = ((Form_pg_attribute) GETSTRUCT(tuple))->attnum;
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
 
 	/* Prevent them from altering a system attribute */
 	if (attnum <= 0)
@@ -7709,12 +7722,20 @@ ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
+	/* TODO: see transformColumnDefinition() */
+	if (attTup->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("not-null constraints are not supported on virtual generated columns"),
+				 errdetail("Column \"%s\" of relation \"%s\" is a virtual generated column.",
+						   colName, RelationGetRelationName(rel))));
+
 	/*
 	 * Okay, actually perform the catalog change ... if needed
 	 */
-	if (!((Form_pg_attribute) GETSTRUCT(tuple))->attnotnull)
+	if (!attTup->attnotnull)
 	{
-		((Form_pg_attribute) GETSTRUCT(tuple))->attnotnull = true;
+		attTup->attnotnull = true;
 
 		CatalogTupleUpdate(attr_rel, &tuple->t_self, tuple);
 
@@ -7725,7 +7746,7 @@ ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 		 * already found that we must verify some other not-null constraint.
 		 */
 		if (!tab->verify_new_notnull &&
-			!NotNullImpliedByRelConstraints(rel, (Form_pg_attribute) GETSTRUCT(tuple)))
+			!NotNullImpliedByRelConstraints(rel, attTup))
 		{
 			/* Tell Phase 3 it needs to test the constraint */
 			tab->verify_new_notnull = true;
@@ -8307,7 +8328,18 @@ ATExecSetExpression(AlteredTableInfo *tab, Relation rel, const char *colName,
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
-	if (attTup->attgenerated != ATTRIBUTE_GENERATED_STORED)
+	/*
+	 * TODO: This could be done, but it would need a different implementation:
+	 * no rewriting, but still need to recheck any constraints.
+	 */
+	if (attTup->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("ALTER TABLE / SET EXPRESSION is not supported for virtual generated columns"),
+				 errdetail("Column \"%s\" of relation \"%s\" is a virtual generated column.",
+						   colName, RelationGetRelationName(rel))));
+
+	if (!attTup->attgenerated)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 				 errmsg("column \"%s\" of relation \"%s\" is not a generated column",
@@ -8464,17 +8496,30 @@ ATExecDropExpression(Relation rel, const char *colName, bool missing_ok, LOCKMOD
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
-	if (attTup->attgenerated != ATTRIBUTE_GENERATED_STORED)
+	/*
+	 * TODO: This could be done, but it would need a table rewrite to
+	 * materialize the generated values.  Note that for the time being, we
+	 * still error with missing_ok, so that we don't silently leave the column
+	 * as generated.
+	 */
+	if (attTup->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("ALTER TABLE / DROP EXPRESSION is not supported for virtual generated columns"),
+				 errdetail("Column \"%s\" of relation \"%s\" is a virtual generated column.",
+						   colName, RelationGetRelationName(rel))));
+
+	if (!attTup->attgenerated)
 	{
 		if (!missing_ok)
 			ereport(ERROR,
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-					 errmsg("column \"%s\" of relation \"%s\" is not a stored generated column",
+					 errmsg("column \"%s\" of relation \"%s\" is not a generated column",
 							colName, RelationGetRelationName(rel))));
 		else
 		{
 			ereport(NOTICE,
-					(errmsg("column \"%s\" of relation \"%s\" is not a stored generated column, skipping",
+					(errmsg("column \"%s\" of relation \"%s\" is not a generated column, skipping",
 							colName, RelationGetRelationName(rel))));
 			heap_freetuple(tuple);
 			table_close(attrelation, RowExclusiveLock);
@@ -9696,6 +9741,19 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 						 errmsg("invalid %s action for foreign key constraint containing generated column",
 								"ON DELETE")));
 		}
+
+		/*
+		 * FKs on virtual columns are not supported.  This would require
+		 * various additional support in ri_triggers.c, including special
+		 * handling in ri_NullCheck(), ri_KeysEqual(),
+		 * RI_FKey_fk_upd_check_required() (since all virtual columns appear
+		 * as NULL there).  Also not really practical as long as you can't
+		 * index virtual columns.
+		 */
+		if (attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("foreign key constraints on virtual generated columns are not supported")));
 	}
 
 	/*
@@ -11659,7 +11717,7 @@ ATExecValidateConstraint(List **wqueue, Relation rel, char *constrName,
 			val = SysCacheGetAttrNotNull(CONSTROID, tuple,
 										 Anum_pg_constraint_conbin);
 			conbin = TextDatumGetCString(val);
-			newcon->qual = (Node *) stringToNode(conbin);
+			newcon->qual = (Node *) expand_generated_columns_in_expr(stringToNode(conbin), rel);
 
 			/* Find or create work queue entry for this table */
 			tab = ATGetQueueEntry(wqueue, rel);
@@ -12700,8 +12758,12 @@ ATPrepAlterColumnType(List **wqueue,
 					   list_make1_oid(rel->rd_rel->reltype),
 					   0);
 
-	if (tab->relkind == RELKIND_RELATION ||
-		tab->relkind == RELKIND_PARTITIONED_TABLE)
+	if (attTup->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+	{
+		/* do nothing */
+	}
+	else if (tab->relkind == RELKIND_RELATION ||
+			 tab->relkind == RELKIND_PARTITIONED_TABLE)
 	{
 		/*
 		 * Set up an expression to transform the old data value to the new
@@ -17858,8 +17920,11 @@ ComputePartitionAttrs(ParseState *pstate, Relation rel, List *partParams, AttrNu
 						 parser_errposition(pstate, pelem->location)));
 
 			/*
-			 * Generated columns cannot work: They are computed after BEFORE
-			 * triggers, but partition routing is done before all triggers.
+			 * Stored generated columns cannot work: They are computed after
+			 * BEFORE triggers, but partition routing is done before all
+			 * triggers.  Maybe virtual generated columns could be made to
+			 * work, but then they would need to be handled as an expression
+			 * below.
 			 */
 			if (attform->attgenerated)
 				ereport(ERROR,
@@ -17941,9 +18006,12 @@ ComputePartitionAttrs(ParseState *pstate, Relation rel, List *partParams, AttrNu
 				}
 
 				/*
-				 * Generated columns cannot work: They are computed after
-				 * BEFORE triggers, but partition routing is done before all
-				 * triggers.
+				 * Stored generated columns cannot work: They are computed
+				 * after BEFORE triggers, but partition routing is done before
+				 * all triggers.  Virtual generated columns could probably
+				 * work, but it would require more work elsewhere (for example
+				 * SET EXPRESSION would need to check whether the column is
+				 * used in partition keys).  Seems safer to prohibit for now.
 				 */
 				i = -1;
 				while ((i = bms_next_member(expr_attrs, i)) >= 0)
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index 95de402fa65..92c8c9824e2 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -43,6 +43,7 @@
 #include "parser/parse_relation.h"
 #include "partitioning/partdesc.h"
 #include "pgstat.h"
+#include "rewrite/rewriteHandler.h"
 #include "rewrite/rewriteManip.h"
 #include "storage/lmgr.h"
 #include "utils/acl.h"
@@ -101,6 +102,7 @@ static void AfterTriggerSaveEvent(EState *estate, ResultRelInfo *relinfo,
 								  bool is_crosspart_update);
 static void AfterTriggerEnlargeQueryState(void);
 static bool before_stmt_triggers_fired(Oid relid, CmdType cmdType);
+static void check_modified_virtual_generated(TupleDesc tupdesc, HeapTuple tuple);

 /*
@@ -641,7 +643,8 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString,
 					if (TRIGGER_FOR_BEFORE(tgtype) &&
 						var->varattno == 0 &&
 						RelationGetDescr(rel)->constr &&
-						RelationGetDescr(rel)->constr->has_generated_stored)
+						(RelationGetDescr(rel)->constr->has_generated_stored ||
+						 RelationGetDescr(rel)->constr->has_generated_virtual))
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 								 errmsg("BEFORE trigger's WHEN condition cannot reference NEW generated columns"),
@@ -942,6 +945,13 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString,
 						 errmsg("column \"%s\" of relation \"%s\" does not exist",
 								name, RelationGetRelationName(rel))));
 
+			/* Currently doesn't work. */
+			if (TupleDescAttr(RelationGetDescr(rel), attnum - 1)->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+				ereport(ERROR,
+						errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("virtual generated columns are not supported as trigger columns"),
+						errdetail("Column \"%s\" is a virtual generated column.", name));
+
 			/* Check for duplicates */
 			for (j = i - 1; j >= 0; j--)
 			{
@@ -2501,6 +2511,8 @@ ExecBRInsertTriggers(EState *estate, ResultRelInfo *relinfo,
 		}
 		else if (newtuple != oldtuple)
 		{
+			check_modified_virtual_generated(RelationGetDescr(relinfo->ri_RelationDesc), newtuple);
+
 			ExecForceStoreHeapTuple(newtuple, slot, false);
 
 			/*
@@ -3058,6 +3070,8 @@ ExecBRUpdateTriggers(EState *estate, EPQState *epqstate,
 		}
 		else if (newtuple != oldtuple)
 		{
+			check_modified_virtual_generated(RelationGetDescr(relinfo->ri_RelationDesc), newtuple);
+
 			ExecForceStoreHeapTuple(newtuple, newslot, false);
 
 			/*
@@ -3488,6 +3502,7 @@ TriggerEnabled(EState *estate, ResultRelInfo *relinfo,
 
 			oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
 			tgqual = stringToNode(trigger->tgqual);
+			tgqual = (Node *) expand_generated_columns_in_expr(tgqual, relinfo->ri_RelationDesc);
 			/* Change references to OLD and NEW to INNER_VAR and OUTER_VAR */
 			ChangeVarNodes(tgqual, PRS2_OLD_VARNO, INNER_VAR, 0);
 			ChangeVarNodes(tgqual, PRS2_NEW_VARNO, OUTER_VAR, 0);
@@ -6593,3 +6608,34 @@ pg_trigger_depth(PG_FUNCTION_ARGS)
 {
 	PG_RETURN_INT32(MyTriggerDepth);
 }
+
+/*
+ * Check whether a trigger modified a virtual generated column and error if
+ * so.
+ *
+ * We need to check this so that we don't end up storing a non-null value in a
+ * virtual generated column.
+ *
+ * We don't need to check for stored generated columns, since those will be
+ * overwritten later anyway.
+ */
+static void
+check_modified_virtual_generated(TupleDesc tupdesc, HeapTuple tuple)
+{
+	if (!(tupdesc->constr && tupdesc->constr->has_generated_virtual))
+		return;
+
+	for (int i = 0; i < tupdesc->natts; i++)
+	{
+		if (TupleDescAttr(tupdesc, i)->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+		{
+			bool		isnull;
+
+			fastgetattr(tuple, i + 1, tupdesc, &isnull);
+			if (!isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
+						 errmsg("trigger modified virtual generated column value")));
+		}
+	}
+}
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 852186312c5..3eeddc81311 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -2001,6 +2001,10 @@ CheckVarSlotCompatibility(TupleTableSlot *slot, int attnum, Oid vartype)
 
 		attr = TupleDescAttr(slot_tupdesc, attnum - 1);
 
+		/* Internal error: somebody forgot to expand it. */
+		if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+			elog(ERROR, "unexpected virtual generated column reference");
+
 		if (attr->attisdropped)
 			ereport(ERROR,
 					(errcode(ERRCODE_UNDEFINED_COLUMN),
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 4d7c92d63c1..d82170785bf 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -1748,6 +1748,7 @@ ExecRelCheck(ResultRelInfo *resultRelInfo,
 			Expr	   *checkconstr;
 
 			checkconstr = stringToNode(check[i].ccbin);
+			checkconstr = (Expr *) expand_generated_columns_in_expr((Node *) checkconstr, rel);
 			resultRelInfo->ri_ConstraintExprs[i] =
 				ExecPrepareExpr(checkconstr, estate);
 		}
@@ -2295,7 +2296,9 @@ ExecBuildSlotValueDescription(Oid reloid,
 
 		if (table_perm || column_perm)
 		{
-			if (slot->tts_isnull[i])
+			if (att->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+				val = "virtual";
+			else if (slot->tts_isnull[i])
 				val = "null";
 			else
 			{
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 28fed9d87f6..01dedbfc396 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -562,6 +562,7 @@ transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt)
 	qry->hasWindowFuncs = pstate->p_hasWindowFuncs;
 	qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
 	qry->hasAggs = pstate->p_hasAggs;
+	qry->hasGeneratedVirtual = pstate->p_hasGeneratedVirtual;
 
 	assign_query_collations(pstate, qry);
 
@@ -988,6 +989,7 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 
 	qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
 	qry->hasSubLinks = pstate->p_hasSubLinks;
+	qry->hasGeneratedVirtual = pstate->p_hasGeneratedVirtual;
 
 	assign_query_collations(pstate, qry);
 
@@ -1453,6 +1455,7 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
 	qry->hasWindowFuncs = pstate->p_hasWindowFuncs;
 	qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
 	qry->hasAggs = pstate->p_hasAggs;
+	qry->hasGeneratedVirtual = pstate->p_hasGeneratedVirtual;
 
 	foreach(l, stmt->lockingClause)
 	{
@@ -1679,6 +1682,7 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 	qry->jointree = makeFromExpr(pstate->p_joinlist, NULL);
 
 	qry->hasSubLinks = pstate->p_hasSubLinks;
+	qry->hasGeneratedVirtual = pstate->p_hasGeneratedVirtual;
 
 	assign_query_collations(pstate, qry);
 
@@ -1930,6 +1934,7 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 	qry->hasWindowFuncs = pstate->p_hasWindowFuncs;
 	qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
 	qry->hasAggs = pstate->p_hasAggs;
+	qry->hasGeneratedVirtual = pstate->p_hasGeneratedVirtual;
 
 	foreach(l, lockingClause)
 	{
@@ -2404,6 +2409,7 @@ transformReturnStmt(ParseState *pstate, ReturnStmt *stmt)
 	qry->hasWindowFuncs = pstate->p_hasWindowFuncs;
 	qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
 	qry->hasAggs = pstate->p_hasAggs;
+	qry->hasGeneratedVirtual = pstate->p_hasGeneratedVirtual;
 
 	assign_query_collations(pstate, qry);
 
@@ -2471,6 +2477,7 @@ transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt)
 
 	qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
 	qry->hasSubLinks = pstate->p_hasSubLinks;
+	qry->hasGeneratedVirtual = pstate->p_hasGeneratedVirtual;
 
 	assign_query_collations(pstate, qry);
 
@@ -2837,6 +2844,7 @@ transformPLAssignStmt(ParseState *pstate, PLAssignStmt *stmt)
 	qry->hasWindowFuncs = pstate->p_hasWindowFuncs;
 	qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
 	qry->hasAggs = pstate->p_hasAggs;
+	qry->hasGeneratedVirtual = pstate->p_hasGeneratedVirtual;
 
 	foreach(l, sstmt->lockingClause)
 	{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 4d582950b72..6c80405c48e 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -641,7 +641,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <str>		opt_existing_window_name
 %type <boolean> opt_if_not_exists
 %type <boolean> opt_unique_null_treatment
-%type <ival>	generated_when override_kind
+%type <ival>	generated_when override_kind opt_virtual_or_stored
 %type <partspec>	PartitionSpec OptPartitionSpec
 %type <partelem>	part_elem
 %type <list>		part_params
@@ -791,7 +791,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	UNLISTEN UNLOGGED UNTIL UPDATE USER USING
 
 	VACUUM VALID VALIDATE VALIDATOR VALUE_P VALUES VARCHAR VARIADIC VARYING
-	VERBOSE VERSION_P VIEW VIEWS VOLATILE
+	VERBOSE VERSION_P VIEW VIEWS VIRTUAL VOLATILE
 
 	WHEN WHERE WHITESPACE_P WINDOW WITH WITHIN WITHOUT WORK WRAPPER WRITE
 
@@ -4025,7 +4025,7 @@ ColConstraintElem:
 					n->location = @1;
 					$$ = (Node *) n;
 				}
-			| GENERATED generated_when AS '(' a_expr ')' STORED
+			| GENERATED generated_when AS '(' a_expr ')' opt_virtual_or_stored
 				{
 					Constraint *n = makeNode(Constraint);
 
@@ -4033,6 +4033,7 @@ ColConstraintElem:
 					n->generated_when = $2;
 					n->raw_expr = $5;
 					n->cooked_expr = NULL;
+					n->generated_kind = $7;
 					n->location = @1;
 
 					/*
@@ -4079,6 +4080,12 @@ generated_when:
 			| BY DEFAULT	{ $$ = ATTRIBUTE_IDENTITY_BY_DEFAULT; }
 		;
 
+opt_virtual_or_stored:
+			STORED			{ $$ = ATTRIBUTE_GENERATED_STORED; }
+			| VIRTUAL		{ $$ = ATTRIBUTE_GENERATED_VIRTUAL; }
+			| /*EMPTY*/		{ $$ = ATTRIBUTE_GENERATED_VIRTUAL; }
+		;
+
 /*
  * ConstraintAttr represents constraint attributes, which we parse as if
  * they were independent constraint clauses, in order to avoid shift/reduce
@@ -17882,6 +17889,7 @@ unreserved_keyword:
 			| VERSION_P
 			| VIEW
 			| VIEWS
+			| VIRTUAL
 			| VOLATILE
 			| WHITESPACE_P
 			| WITHIN
@@ -18538,6 +18546,7 @@ bare_label_keyword:
 			| VERSION_P
 			| VIEW
 			| VIEWS
+			| VIRTUAL
 			| VOLATILE
 			| WHEN
 			| WHITESPACE_P
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
index 8118036495b..48524ac3fc2 100644
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -207,6 +207,10 @@ setTargetTable(ParseState *pstate, RangeVar *relation,
 	pstate->p_target_relation = parserOpenTable(pstate, relation,
 												RowExclusiveLock);
 
+	if (pstate->p_target_relation->rd_att->constr &&
+		pstate->p_target_relation->rd_att->constr->has_generated_virtual)
+		pstate->p_hasGeneratedVirtual = true;
+
 	/*
 	 * Now build an RTE and a ParseNamespaceItem.
 	 */
diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index 2f64eaf0e37..b864749f09c 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -704,7 +704,11 @@ scanNSItemForColumn(ParseState *pstate, ParseNamespaceItem *nsitem,
 						colname),
 				 parser_errposition(pstate, location)));
 
-	/* In generated column, no system column is allowed except tableOid */
+	/*
+	 * In generated column, no system column is allowed except tableOid.
+	 * (Required for stored generated, but we also do it for virtual generated
+	 * for now for consistency.)
+	 */
 	if (pstate->p_expr_kind == EXPR_KIND_GENERATED_COLUMN &&
 		attnum < InvalidAttrNumber && attnum != TableOidAttributeNumber)
 		ereport(ERROR,
@@ -1511,6 +1515,9 @@ addRangeTableEntry(ParseState *pstate,
 	rte->eref = makeAlias(refname, NIL);
 	buildRelationAliases(rel->rd_att, alias, rte->eref);
 
+	if (rel->rd_att->constr && rel->rd_att->constr->has_generated_virtual)
+		pstate->p_hasGeneratedVirtual = true;
+
 	/*
 	 * Set flags and initialize access permissions.
 	 *
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 639cfa443e2..0ae731861a6 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -760,10 +760,36 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 									column->colname, cxt->relation->relname),
 							 parser_errposition(cxt->pstate,
 												constraint->location)));
-				column->generated = ATTRIBUTE_GENERATED_STORED;
+				column->generated = constraint->generated_kind;
 				column->raw_default = constraint->raw_expr;
 				Assert(constraint->cooked_expr == NULL);
 				saw_generated = true;
+
+				/*
+				 * TODO: Prevent virtual generated columns from having a
+				 * domain type.  We would have to enforce domain constraints
+				 * when columns underlying the generated column change.  This
+				 * could possibly be implemented, but it's not.
+				 *
+				 * XXX If column->typeName is not set, then this column
+				 * definition is probably a partition definition and will
+				 * presumably get its pre-vetted type from elsewhere.  If that
+				 * doesn't hold, maybe this check needs to be moved elsewhere.
+				 */
+				if (column->generated == ATTRIBUTE_GENERATED_VIRTUAL && column->typeName)
+				{
+					Type		ctype;
+
+					ctype = typenameType(cxt->pstate, column->typeName, NULL);
+					if (((Form_pg_type) GETSTRUCT(ctype))->typtype == TYPTYPE_DOMAIN)
+						ereport(ERROR,
+								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+								 errmsg("virtual generated column \"%s\" cannot have a domain type",
+										column->colname),
+								 parser_errposition(cxt->pstate,
+													column->location)));
+					ReleaseSysCache(ctype);
+				}
 				break;
 
 			case CONSTR_CHECK:
@@ -848,6 +874,18 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 							column->colname, cxt->relation->relname),
 					 parser_errposition(cxt->pstate,
 										constraint->location)));
+
+		/*
+		 * TODO: Straightforward not-null constraints won't work on virtual
+		 * generated columns, because there is no support for expanding the
+		 * column when the constraint is checked.  Maybe we could convert the
+		 * not-null constraint into a full check constraint, so that the
+		 * generation expression can be expanded at check time.
+		 */
+		if (column->is_not_null && column->generated == ATTRIBUTE_GENERATED_VIRTUAL)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("not-null constraints are not supported on virtual generated columns")));
 	}
 
 	/*
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index d2b35cfb96d..e44ec8ae644 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -27,6 +27,7 @@
 #include "replication/logicalproto.h"
 #include "replication/origin.h"
 #include "replication/pgoutput.h"
+#include "rewrite/rewriteHandler.h"
 #include "utils/builtins.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
@@ -996,7 +997,7 @@ pgoutput_row_filter_init(PGOutputData *data, List *publications,
 				continue;
 
 			foreach(lc, rfnodes[idx])
-				filters = lappend(filters, stringToNode((char *) lfirst(lc)));
+				filters = lappend(filters, expand_generated_columns_in_expr(stringToNode((char *) lfirst(lc)), relation));
 
 			/* combine the row filter and cache the ExprState */
 			rfnode = make_orclause(filters);
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index 8a29fbbc465..2e5b48a533e 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -89,6 +89,8 @@ static List *matchLocks(CmdType event, Relation relation,
 						int varno, Query *parsetree, bool *hasUpdate);
 static Query *fireRIRrules(Query *parsetree, List *activeRIRs);
 static Bitmapset *adjust_view_column_set(Bitmapset *cols, List *targetlist);
+struct expand_generated_context;
+static Query *expand_generated_columns_in_query(Query *query, struct expand_generated_context *context);

 /*
@@ -973,7 +975,8 @@ rewriteTargetListIU(List *targetList,
 		if (att_tup->attgenerated)
 		{
 			/*
-			 * stored generated column will be fixed in executor
+			 * virtual generated column stores a null value; stored generated
+			 * column will be fixed in executor
 			 */
 			new_tle = NULL;
 		}
@@ -4341,6 +4344,150 @@ RewriteQuery(Query *parsetree, List *rewrite_events, int orig_rt_length)
 }

+static Node *
+expand_generated_columns_in_expr_mutator(Node *node, Relation rel)
+{
+	if (node == NULL)
+		return NULL;
+
+	if (IsA(node, Var))
+	{
+		Var		   *v = (Var *) node;
+		AttrNumber	attnum = v->varattno;
+
+		if (attnum > 0 && TupleDescAttr(RelationGetDescr(rel), attnum - 1)->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+		{
+			node = build_column_default(rel, attnum);
+			if (node == NULL)
+				elog(ERROR, "no generation expression found for column number %d of table \"%s\"",
+					 attnum, RelationGetRelationName(rel));
+			ChangeVarNodes(node, 1, v->varno, 0);
+		}
+
+		return node;
+	}
+	else
+		return expression_tree_mutator(node, expand_generated_columns_in_expr_mutator, rel);
+}
+
+
+Node *
+expand_generated_columns_in_expr(Node *node, Relation rel)
+{
+	TupleDesc	tupdesc = RelationGetDescr(rel);
+
+	if (tupdesc->constr && tupdesc->constr->has_generated_virtual)
+		return expression_tree_mutator(node,
+									   expand_generated_columns_in_expr_mutator,
+									   rel);
+	else
+		return node;
+}
+
+struct expand_generated_context
+{
+	/* list of range tables, innermost last */
+	List	   *rtables;
+};
+
+static Node *
+expand_generated_columns_in_query_mutator(Node *node, struct expand_generated_context *context)
+{
+	if (node == NULL)
+		return NULL;
+
+	if (IsA(node, Var))
+	{
+		Var		   *v = (Var *) node;
+		Oid			relid;
+		AttrNumber	attnum;
+		List	   *rtable = list_nth_node(List,
+										   context->rtables,
+										   list_length(context->rtables) - v->varlevelsup - 1);
+
+		relid = rt_fetch(v->varno, rtable)->relid;
+		attnum = v->varattno;
+
+		if (!relid || !attnum)
+			return node;
+
+		if (get_attgenerated(relid, attnum) == ATTRIBUTE_GENERATED_VIRTUAL)
+		{
+			Relation	rt_entry_relation = table_open(relid, NoLock);
+
+			node = build_column_default(rt_entry_relation, attnum);
+			if (node == NULL)
+				elog(ERROR, "no generation expression found for column number %d of table \"%s\"",
+					 attnum, RelationGetRelationName(rt_entry_relation));
+			ChangeVarNodes(node, 1, v->varno, v->varlevelsup);
+
+			table_close(rt_entry_relation, NoLock);
+		}
+
+		return node;
+	}
+	else if (IsA(node, Query))
+	{
+		Query	   *query = (Query *) node;
+
+		query = expand_generated_columns_in_query(query, context);
+
+		return (Node *) query;
+	}
+	else
+		return expression_tree_mutator(node, expand_generated_columns_in_query_mutator, context);
+}
+
+/*
+ * Expand virtual generated columns in a Query.  We do some optimizations here
+ * to avoid digging through the whole Query unless necessary.
+ */
+static Query *
+expand_generated_columns_in_query(Query *query, struct expand_generated_context *context)
+{
+	context->rtables = lappend(context->rtables, query->rtable);
+
+	/*
+	 * If any table in the query has a virtual column or there is a sublink,
+	 * then we need to do the whole walk.
+	 */
+	if (query->hasGeneratedVirtual || query->hasSubLinks)
+	{
+		query = query_tree_mutator(query,
+								   expand_generated_columns_in_query_mutator,
+								   context,
+								   QTW_DONT_COPY_QUERY);
+	}
+
+	/*
+	 * Else we only need to process subqueries.
+	 */
+	else
+	{
+		ListCell   *lc;
+
+		foreach(lc, query->rtable)
+		{
+			RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
+
+			if (rte->rtekind == RTE_SUBQUERY)
+				rte->subquery = expand_generated_columns_in_query(rte->subquery, context);
+		}
+
+		foreach(lc, query->cteList)
+		{
+			CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
+
+			cte->ctequery = (Node *) expand_generated_columns_in_query(castNode(Query, cte->ctequery), context);
+		}
+	}
+
+	context->rtables = list_truncate(context->rtables, list_length(context->rtables) - 1);
+
+	return query;
+}
+
+
 /*
  * QueryRewrite -
  *	  Primary entry point to the query rewriter.
@@ -4396,6 +4543,21 @@ QueryRewrite(Query *parsetree)
 	/*
 	 * Step 3
 	 *
+	 * Expand virtual generated columns.
+	 */
+	foreach(l, querylist)
+	{
+		Query	   *query = (Query *) lfirst(l);
+		struct expand_generated_context context;
+
+		context.rtables = NIL;
+
+		query = expand_generated_columns_in_query(query, &context);
+	}
+
+	/*
+	 * Step 4
+	 *
 	 * Determine which, if any, of the resulting queries is supposed to set
 	 * the command-result tag; and update the canSetTag fields accordingly.
 	 *
diff --git a/src/backend/utils/cache/partcache.c b/src/backend/utils/cache/partcache.c
index beec6cddbc4..1dee7c1e899 100644
--- a/src/backend/utils/cache/partcache.c
+++ b/src/backend/utils/cache/partcache.c
@@ -26,6 +26,7 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/optimizer.h"
 #include "partitioning/partbounds.h"
+#include "rewrite/rewriteHandler.h"
 #include "utils/builtins.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
@@ -148,6 +149,8 @@ RelationBuildPartitionKey(Relation relation)
 		expr = stringToNode(exprString);
 		pfree(exprString);
 
+		expr = expand_generated_columns_in_expr(expr, relation);
+
 		/*
 		 * Run the expressions through const-simplification since the planner
 		 * will be comparing them to similarly-processed qual clause operands,
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index b09f6a90e44..747322e8136 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -588,6 +588,8 @@ RelationBuildTupleDesc(Relation relation)
 			constr->has_not_null = true;
 		if (attp->attgenerated == ATTRIBUTE_GENERATED_STORED)
 			constr->has_generated_stored = true;
+		if (attp->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+			constr->has_generated_virtual = true;
 		if (attp->atthasdef)
 			ndef++;
 
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index e3240708284..f4b147e48b4 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -16004,6 +16004,9 @@ dumpTableSchema(Archive *fout, const TableInfo *tbinfo)
 						if (tbinfo->attgenerated[j] == ATTRIBUTE_GENERATED_STORED)
 							appendPQExpBuffer(q, " GENERATED ALWAYS AS (%s) STORED",
 											  tbinfo->attrdefs[j]->adef_expr);
+						else if (tbinfo->attgenerated[j] == ATTRIBUTE_GENERATED_VIRTUAL)
+							appendPQExpBuffer(q, " GENERATED ALWAYS AS (%s)",
+											  tbinfo->attrdefs[j]->adef_expr);
 						else
 							appendPQExpBuffer(q, " DEFAULT %s",
 											  tbinfo->attrdefs[j]->adef_expr);
diff --git a/src/bin/pg_dump/t/002_pg_dump.pl b/src/bin/pg_dump/t/002_pg_dump.pl
index d3dd8784d64..794610ee010 100644
--- a/src/bin/pg_dump/t/002_pg_dump.pl
+++ b/src/bin/pg_dump/t/002_pg_dump.pl
@@ -3595,12 +3595,14 @@
 		create_order => 3,
 		create_sql => 'CREATE TABLE dump_test.test_table_generated (
 						   col1 int primary key,
-						   col2 int generated always as (col1 * 2) stored
+						   col2 int generated always as (col1 * 2) stored,
+						   col3 int generated always as (col1 * 3) virtual
 					   );',
 		regexp => qr/^
 			\QCREATE TABLE dump_test.test_table_generated (\E\n
 			\s+\Qcol1 integer NOT NULL,\E\n
-			\s+\Qcol2 integer GENERATED ALWAYS AS ((col1 * 2)) STORED\E\n
+			\s+\Qcol2 integer GENERATED ALWAYS AS ((col1 * 2)) STORED,\E\n
+			\s+\Qcol3 integer GENERATED ALWAYS AS ((col1 * 3))\E\n
 			\);
 			/xms,
 		like =>
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index f67bf0b8925..7474a481559 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -2089,6 +2089,12 @@ describeOneTableDetails(const char *schemaname,
 									   PQgetvalue(res, i, attrdef_col));
 				mustfree = true;
 			}
+			else if (generated[0] == ATTRIBUTE_GENERATED_VIRTUAL)
+			{
+				default_str = psprintf("generated always as (%s)",
+									   PQgetvalue(res, i, attrdef_col));
+				mustfree = true;
+			}
 			else
 				default_str = PQgetvalue(res, i, attrdef_col);
 
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index 8930a28d660..6ef40249583 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -43,6 +43,7 @@ typedef struct TupleConstr
 	uint16		num_check;
 	bool		has_not_null;
 	bool		has_generated_stored;
+	bool		has_generated_virtual;
 } TupleConstr;
 
 /*
diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index 1c62b8bfcb5..8f158dc6083 100644
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -234,6 +234,7 @@ MAKE_SYSCACHE(ATTNUM, pg_attribute_relid_attnum_index, 128);
 #define		  ATTRIBUTE_IDENTITY_BY_DEFAULT 'd'
 
 #define		  ATTRIBUTE_GENERATED_STORED	's'
+#define		  ATTRIBUTE_GENERATED_VIRTUAL	'v'
 
 #endif							/* EXPOSE_TO_CLIENT_CODE */
 
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index ddfed02db22..3163fff7db0 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -160,6 +160,8 @@ typedef struct Query
 	bool		hasForUpdate pg_node_attr(query_jumble_ignore);
 	/* rewriter has applied some RLS policy */
 	bool		hasRowSecurity pg_node_attr(query_jumble_ignore);
+	/* some table has a virtual generated column */
+	bool		hasGeneratedVirtual pg_node_attr(query_jumble_ignore);
 	/* is a RETURN statement */
 	bool		isReturn pg_node_attr(query_jumble_ignore);
 
@@ -2745,6 +2747,7 @@ typedef struct Constraint
 	char	   *cooked_expr;	/* CHECK or DEFAULT expression, as
 								 * nodeToString representation */
 	char		generated_when; /* ALWAYS or BY DEFAULT */
+	char		generated_kind; /* STORED or VIRTUAL */
 	int			inhcount;		/* initial inheritance count to apply, for
 								 * "raw" NOT NULL constraints */
 	bool		nulls_not_distinct; /* null treatment for UNIQUE constraints */
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index f7fe834cf45..96167877b75 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -492,6 +492,7 @@ PG_KEYWORD("verbose", VERBOSE, TYPE_FUNC_NAME_KEYWORD, BARE_LABEL)
 PG_KEYWORD("version", VERSION_P, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("view", VIEW, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("views", VIEWS, UNRESERVED_KEYWORD, BARE_LABEL)
+PG_KEYWORD("virtual", VIRTUAL, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("volatile", VOLATILE, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("when", WHEN, RESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("where", WHERE, RESERVED_KEYWORD, AS_LABEL)
diff --git a/src/include/parser/parse_node.h b/src/include/parser/parse_node.h
index 5b781d87a9d..1b02128548b 100644
--- a/src/include/parser/parse_node.h
+++ b/src/include/parser/parse_node.h
@@ -225,6 +225,7 @@ struct ParseState
 	bool		p_hasTargetSRFs;
 	bool		p_hasSubLinks;
 	bool		p_hasModifyingCTE;
+	bool		p_hasGeneratedVirtual;
 
 	Node	   *p_last_srf;		/* most recent set-returning func/op found */
 
diff --git a/src/include/rewrite/rewriteHandler.h b/src/include/rewrite/rewriteHandler.h
index 1b65cda71cf..a646a20675a 100644
--- a/src/include/rewrite/rewriteHandler.h
+++ b/src/include/rewrite/rewriteHandler.h
@@ -38,4 +38,6 @@ extern void error_view_not_updatable(Relation view,
 									 List *mergeActionList,
 									 const char *detail);
 
+extern Node *expand_generated_columns_in_expr(Node *node, Relation rel);
+
 #endif							/* REWRITEHANDLER_H */
diff --git a/src/pl/plperl/expected/plperl_trigger.out b/src/pl/plperl/expected/plperl_trigger.out
index d4879e2f03b..42c52ecbba8 100644
--- a/src/pl/plperl/expected/plperl_trigger.out
+++ b/src/pl/plperl/expected/plperl_trigger.out
@@ -8,7 +8,8 @@ CREATE TABLE trigger_test (
 );
 CREATE TABLE trigger_test_generated (
     i int,
-    j int GENERATED ALWAYS AS (i * 2) STORED
+    j int GENERATED ALWAYS AS (i * 2) STORED,
+    k int GENERATED ALWAYS AS (i * 3) VIRTUAL
 );
 CREATE OR REPLACE FUNCTION trigger_data() RETURNS trigger LANGUAGE plperl AS $$
 
@@ -386,7 +387,7 @@ INSERT INTO trigger_test_generated (i) VALUES (1);
 ERROR:  cannot set generated column "j"
 CONTEXT:  PL/Perl function "generated_test_func1"
 SELECT * FROM trigger_test_generated;
- i | j 
----+---
+ i | j | k 
+---+---+---
 (0 rows)
 
diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index d68ad7be345..9611aa82352 100644
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -3052,6 +3052,9 @@ plperl_hash_from_tuple(HeapTuple tuple, TupleDesc tupdesc, bool include_generate
 			/* don't include unless requested */
 			if (!include_generated)
 				continue;
+			/* never include virtual columns */
+			if (att->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+				continue;
 		}
 
 		attname = NameStr(att->attname);
diff --git a/src/pl/plperl/sql/plperl_trigger.sql b/src/pl/plperl/sql/plperl_trigger.sql
index 4adddeb80ac..2798a02fa12 100644
--- a/src/pl/plperl/sql/plperl_trigger.sql
+++ b/src/pl/plperl/sql/plperl_trigger.sql
@@ -10,7 +10,8 @@ CREATE TABLE trigger_test (
 
 CREATE TABLE trigger_test_generated (
     i int,
-    j int GENERATED ALWAYS AS (i * 2) STORED
+    j int GENERATED ALWAYS AS (i * 2) STORED,
+    k int GENERATED ALWAYS AS (i * 3) VIRTUAL
 );
 
 CREATE OR REPLACE FUNCTION trigger_data() RETURNS trigger LANGUAGE plperl AS $$
diff --git a/src/pl/plpython/expected/plpython_trigger.out b/src/pl/plpython/expected/plpython_trigger.out
index 4cb90cb5204..64eab2fa3f4 100644
--- a/src/pl/plpython/expected/plpython_trigger.out
+++ b/src/pl/plpython/expected/plpython_trigger.out
@@ -69,7 +69,8 @@ CREATE TABLE trigger_test
 	(i int, v text );
 CREATE TABLE trigger_test_generated (
 	i int,
-        j int GENERATED ALWAYS AS (i * 2) STORED
+        j int GENERATED ALWAYS AS (i * 2) STORED,
+        k int GENERATED ALWAYS AS (i * 3) VIRTUAL
 );
 CREATE FUNCTION trigger_data() RETURNS trigger LANGUAGE plpython3u AS $$
 
@@ -614,8 +615,8 @@ ERROR:  cannot set generated column "j"
 CONTEXT:  while modifying trigger row
 PL/Python function "generated_test_func1"
 SELECT * FROM trigger_test_generated;
- i | j 
----+---
+ i | j | k 
+---+---+---
 (0 rows)
 
 -- recursive call of a trigger mustn't corrupt TD (bug #18456)
diff --git a/src/pl/plpython/plpy_typeio.c b/src/pl/plpython/plpy_typeio.c
index db14c5f8dae..51e1d610259 100644
--- a/src/pl/plpython/plpy_typeio.c
+++ b/src/pl/plpython/plpy_typeio.c
@@ -844,6 +844,9 @@ PLyDict_FromTuple(PLyDatumToOb *arg, HeapTuple tuple, TupleDesc desc, bool inclu
 				/* don't include unless requested */
 				if (!include_generated)
 					continue;
+				/* never include virtual columns */
+				if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+					continue;
 			}
 
 			key = NameStr(attr->attname);
diff --git a/src/pl/plpython/sql/plpython_trigger.sql b/src/pl/plpython/sql/plpython_trigger.sql
index f6c2ef8d6a0..440549c0785 100644
--- a/src/pl/plpython/sql/plpython_trigger.sql
+++ b/src/pl/plpython/sql/plpython_trigger.sql
@@ -69,7 +69,8 @@ CREATE TABLE trigger_test
 
 CREATE TABLE trigger_test_generated (
 	i int,
-        j int GENERATED ALWAYS AS (i * 2) STORED
+        j int GENERATED ALWAYS AS (i * 2) STORED,
+        k int GENERATED ALWAYS AS (i * 3) VIRTUAL
 );
 
 CREATE FUNCTION trigger_data() RETURNS trigger LANGUAGE plpython3u AS $$
diff --git a/src/pl/tcl/expected/pltcl_trigger.out b/src/pl/tcl/expected/pltcl_trigger.out
index 008ea195095..3bf63ba6133 100644
--- a/src/pl/tcl/expected/pltcl_trigger.out
+++ b/src/pl/tcl/expected/pltcl_trigger.out
@@ -63,7 +63,8 @@ CREATE TABLE trigger_test (
 ALTER TABLE trigger_test DROP dropme;
 CREATE TABLE trigger_test_generated (
    i int,
-   j int GENERATED ALWAYS AS (i * 2) STORED
+   j int GENERATED ALWAYS AS (i * 2) STORED,
+   k int GENERATED ALWAYS AS (i * 3) VIRTUAL
 );
 CREATE VIEW trigger_test_view AS SELECT i, v FROM trigger_test;
 CREATE FUNCTION trigger_data() returns trigger language pltcl as $_$
@@ -647,7 +648,7 @@ NOTICE:  OLD: {}
 NOTICE:  TG_level: ROW
 NOTICE:  TG_name: show_trigger_data_trig_before
 NOTICE:  TG_op: INSERT
-NOTICE:  TG_relatts: {{} i j}
+NOTICE:  TG_relatts: {{} i j k}
 NOTICE:  TG_relid: bogus:12345
 NOTICE:  TG_table_name: trigger_test_generated
 NOTICE:  TG_table_schema: public
@@ -658,7 +659,7 @@ NOTICE:  OLD: {}
 NOTICE:  TG_level: ROW
 NOTICE:  TG_name: show_trigger_data_trig_after
 NOTICE:  TG_op: INSERT
-NOTICE:  TG_relatts: {{} i j}
+NOTICE:  TG_relatts: {{} i j k}
 NOTICE:  TG_relid: bogus:12345
 NOTICE:  TG_table_name: trigger_test_generated
 NOTICE:  TG_table_schema: public
@@ -670,7 +671,7 @@ NOTICE:  OLD: {i: 1, j: 2}
 NOTICE:  TG_level: ROW
 NOTICE:  TG_name: show_trigger_data_trig_before
 NOTICE:  TG_op: UPDATE
-NOTICE:  TG_relatts: {{} i j}
+NOTICE:  TG_relatts: {{} i j k}
 NOTICE:  TG_relid: bogus:12345
 NOTICE:  TG_table_name: trigger_test_generated
 NOTICE:  TG_table_schema: public
@@ -681,7 +682,7 @@ NOTICE:  OLD: {i: 1, j: 2}
 NOTICE:  TG_level: ROW
 NOTICE:  TG_name: show_trigger_data_trig_after
 NOTICE:  TG_op: UPDATE
-NOTICE:  TG_relatts: {{} i j}
+NOTICE:  TG_relatts: {{} i j k}
 NOTICE:  TG_relid: bogus:12345
 NOTICE:  TG_table_name: trigger_test_generated
 NOTICE:  TG_table_schema: public
@@ -693,7 +694,7 @@ NOTICE:  OLD: {i: 11, j: 22}
 NOTICE:  TG_level: ROW
 NOTICE:  TG_name: show_trigger_data_trig_before
 NOTICE:  TG_op: DELETE
-NOTICE:  TG_relatts: {{} i j}
+NOTICE:  TG_relatts: {{} i j k}
 NOTICE:  TG_relid: bogus:12345
 NOTICE:  TG_table_name: trigger_test_generated
 NOTICE:  TG_table_schema: public
@@ -704,7 +705,7 @@ NOTICE:  OLD: {i: 11, j: 22}
 NOTICE:  TG_level: ROW
 NOTICE:  TG_name: show_trigger_data_trig_after
 NOTICE:  TG_op: DELETE
-NOTICE:  TG_relatts: {{} i j}
+NOTICE:  TG_relatts: {{} i j k}
 NOTICE:  TG_relid: bogus:12345
 NOTICE:  TG_table_name: trigger_test_generated
 NOTICE:  TG_table_schema: public
@@ -882,7 +883,7 @@ TRUNCATE trigger_test_generated;
 INSERT INTO trigger_test_generated (i) VALUES (1);
 ERROR:  cannot set generated column "j"
 SELECT * FROM trigger_test_generated;
- i | j 
----+---
+ i | j | k 
+---+---+---
 (0 rows)
 
diff --git a/src/pl/tcl/pltcl.c b/src/pl/tcl/pltcl.c
index 18d14a2b982..fc2399fc978 100644
--- a/src/pl/tcl/pltcl.c
+++ b/src/pl/tcl/pltcl.c
@@ -3114,6 +3114,9 @@ pltcl_build_tuple_argument(HeapTuple tuple, TupleDesc tupdesc, bool include_gene
 			/* don't include unless requested */
 			if (!include_generated)
 				continue;
+			/* never include virtual columns */
+			if (att->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
+				continue;
 		}
 
 		/************************************************************
diff --git a/src/pl/tcl/sql/pltcl_trigger.sql b/src/pl/tcl/sql/pltcl_trigger.sql
index 2db75a333a0..e4acf6a5fd9 100644
--- a/src/pl/tcl/sql/pltcl_trigger.sql
+++ b/src/pl/tcl/sql/pltcl_trigger.sql
@@ -73,7 +73,8 @@ CREATE TABLE trigger_test (
 
 CREATE TABLE trigger_test_generated (
    i int,
-   j int GENERATED ALWAYS AS (i * 2) STORED
+   j int GENERATED ALWAYS AS (i * 2) STORED,
+   k int GENERATED ALWAYS AS (i * 3) VIRTUAL
 );
 
 CREATE VIEW trigger_test_view AS SELECT i, v FROM trigger_test;
diff --git a/src/test/regress/expected/create_table_like.out b/src/test/regress/expected/create_table_like.out
index 0ed94f1d2fb..4ef8a33858c 100644
--- a/src/test/regress/expected/create_table_like.out
+++ b/src/test/regress/expected/create_table_like.out
@@ -113,19 +113,20 @@ SELECT * FROM test_like_id_3;  -- identity was copied and applied
 (1 row)
 
 DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
-CREATE TABLE test_like_gen_1 (a int, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE test_like_gen_1 (a int, b int GENERATED ALWAYS AS (a * 2) STORED, c int GENERATED ALWAYS AS (a * 3) VIRTUAL);
 \d test_like_gen_1
                         Table "public.test_like_gen_1"
  Column |  Type   | Collation | Nullable |              Default               
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           |          | 
  b      | integer |           |          | generated always as (a * 2) stored
+ c      | integer |           |          | generated always as (a * 3)
 
 INSERT INTO test_like_gen_1 (a) VALUES (1);
 SELECT * FROM test_like_gen_1;
- a | b 
----+---
- 1 | 2
+ a | b | c 
+---+---+---
+ 1 | 2 | 3
 (1 row)
 
 CREATE TABLE test_like_gen_2 (LIKE test_like_gen_1);
@@ -135,12 +136,13 @@ CREATE TABLE test_like_gen_2 (LIKE test_like_gen_1);
 --------+---------+-----------+----------+---------
  a      | integer |           |          | 
  b      | integer |           |          | 
+ c      | integer |           |          | 
 
 INSERT INTO test_like_gen_2 (a) VALUES (1);
 SELECT * FROM test_like_gen_2;
- a | b 
----+---
- 1 |  
+ a | b | c 
+---+---+---
+ 1 |   |  
 (1 row)
 
 CREATE TABLE test_like_gen_3 (LIKE test_like_gen_1 INCLUDING GENERATED);
@@ -150,12 +152,13 @@ CREATE TABLE test_like_gen_3 (LIKE test_like_gen_1 INCLUDING GENERATED);
 --------+---------+-----------+----------+------------------------------------
  a      | integer |           |          | 
  b      | integer |           |          | generated always as (a * 2) stored
+ c      | integer |           |          | generated always as (a * 3)
 
 INSERT INTO test_like_gen_3 (a) VALUES (1);
 SELECT * FROM test_like_gen_3;
- a | b 
----+---
- 1 | 2
+ a | b | c 
+---+---+---
+ 1 | 2 | 3
 (1 row)
 
 DROP TABLE test_like_gen_1, test_like_gen_2, test_like_gen_3;
diff --git a/src/test/regress/expected/generated_stored.out b/src/test/regress/expected/generated_stored.out
index dd74a1a9f0b..c74d6b4e5cf 100644
--- a/src/test/regress/expected/generated_stored.out
+++ b/src/test/regress/expected/generated_stored.out
@@ -1,5 +1,5 @@
 -- sanity check of system catalog
-SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT IN ('', 's');
+SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT IN ('', 's', 'v');
  attrelid | attname | attgenerated 
 ----------+---------+--------------
 (0 rows)
@@ -1091,9 +1091,9 @@ SELECT * FROM gtest29;
 ALTER TABLE gtest29 ALTER COLUMN a SET EXPRESSION AS (a * 3);  -- error
 ERROR:  column "a" of relation "gtest29" is not a generated column
 ALTER TABLE gtest29 ALTER COLUMN a DROP EXPRESSION;  -- error
-ERROR:  column "a" of relation "gtest29" is not a stored generated column
+ERROR:  column "a" of relation "gtest29" is not a generated column
 ALTER TABLE gtest29 ALTER COLUMN a DROP EXPRESSION IF EXISTS;  -- notice
-NOTICE:  column "a" of relation "gtest29" is not a stored generated column, skipping
+NOTICE:  column "a" of relation "gtest29" is not a generated column, skipping
 -- Change the expression
 ALTER TABLE gtest29 ALTER COLUMN b SET EXPRESSION AS (a * 3);
 SELECT * FROM gtest29;
diff --git a/src/test/regress/expected/generated_stored.out b/src/test/regress/expected/generated_virtual.out
similarity index 70%
copy from src/test/regress/expected/generated_stored.out
copy to src/test/regress/expected/generated_virtual.out
index dd74a1a9f0b..16c8e0ede16 100644
--- a/src/test/regress/expected/generated_stored.out
+++ b/src/test/regress/expected/generated_virtual.out
@@ -1,15 +1,15 @@
 -- sanity check of system catalog
-SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT IN ('', 's');
+SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT IN ('', 's', 'v');
  attrelid | attname | attgenerated 
 ----------+---------+--------------
 (0 rows)
 
-CREATE SCHEMA generated_stored_tests;
-GRANT USAGE ON SCHEMA generated_stored_tests TO PUBLIC;
-SET search_path = generated_stored_tests;
-CREATE TABLE gtest0 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (55) STORED);
-CREATE TABLE gtest1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
-SELECT table_name, column_name, column_default, is_nullable, is_generated, generation_expression FROM information_schema.columns WHERE table_schema = 'generated_stored_tests' ORDER BY 1, 2;
+CREATE SCHEMA generated_virtual_tests;
+GRANT USAGE ON SCHEMA generated_virtual_tests TO PUBLIC;
+SET search_path = generated_virtual_tests;
+CREATE TABLE gtest0 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (55) VIRTUAL);
+CREATE TABLE gtest1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
+SELECT table_name, column_name, column_default, is_nullable, is_generated, generation_expression FROM information_schema.columns WHERE table_schema = 'generated_virtual_tests' ORDER BY 1, 2;
  table_name | column_name | column_default | is_nullable | is_generated | generation_expression 
 ------------+-------------+----------------+-------------+--------------+-----------------------
  gtest0     | a           |                | NO          | NEVER        | 
@@ -18,89 +18,89 @@ SELECT table_name, column_name, column_default, is_nullable, is_generated, gener
  gtest1     | b           |                | YES         | ALWAYS       | (a * 2)
 (4 rows)
 
-SELECT table_name, column_name, dependent_column FROM information_schema.column_column_usage WHERE table_schema = 'generated_stored_tests' ORDER BY 1, 2, 3;
+SELECT table_name, column_name, dependent_column FROM information_schema.column_column_usage WHERE table_schema = 'generated_virtual_tests' ORDER BY 1, 2, 3;
  table_name | column_name | dependent_column 
 ------------+-------------+------------------
  gtest1     | a           | b
 (1 row)
 
 \d gtest1
-                    Table "generated_stored_tests.gtest1"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
+                Table "generated_virtual_tests.gtest1"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           | not null | 
- b      | integer |           |          | generated always as (a * 2) stored
+ b      | integer |           |          | generated always as (a * 2)
 Indexes:
     "gtest1_pkey" PRIMARY KEY, btree (a)
 
 -- duplicate generated
-CREATE TABLE gtest_err_1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED GENERATED ALWAYS AS (a * 3) STORED);
+CREATE TABLE gtest_err_1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL GENERATED ALWAYS AS (a * 3) VIRTUAL);
 ERROR:  multiple generation clauses specified for column "b" of table "gtest_err_1"
-LINE 1: ...ARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED GENERATED ...
+LINE 1: ...RY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL GENERATED ...
                                                              ^
 -- references to other generated columns, including self-references
-CREATE TABLE gtest_err_2a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (b * 2) STORED);
+CREATE TABLE gtest_err_2a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (b * 2) VIRTUAL);
 ERROR:  cannot use generated column "b" in column generation expression
-LINE 1: ...2a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (b * 2) STO...
+LINE 1: ...2a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (b * 2) VIR...
                                                              ^
 DETAIL:  A generated column cannot reference another generated column.
-CREATE TABLE gtest_err_2b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED, c int GENERATED ALWAYS AS (b * 3) STORED);
+CREATE TABLE gtest_err_2b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL, c int GENERATED ALWAYS AS (b * 3) VIRTUAL);
 ERROR:  cannot use generated column "b" in column generation expression
-LINE 1: ...AYS AS (a * 2) STORED, c int GENERATED ALWAYS AS (b * 3) STO...
+LINE 1: ...YS AS (a * 2) VIRTUAL, c int GENERATED ALWAYS AS (b * 3) VIR...
                                                              ^
 DETAIL:  A generated column cannot reference another generated column.
 -- a whole-row var is a self-reference on steroids, so disallow that too
 CREATE TABLE gtest_err_2c (a int PRIMARY KEY,
-    b int GENERATED ALWAYS AS (num_nulls(gtest_err_2c)) STORED);
+    b int GENERATED ALWAYS AS (num_nulls(gtest_err_2c)) VIRTUAL);
 ERROR:  cannot use whole-row variable in column generation expression
-LINE 2:     b int GENERATED ALWAYS AS (num_nulls(gtest_err_2c)) STOR...
+LINE 2:     b int GENERATED ALWAYS AS (num_nulls(gtest_err_2c)) VIRT...
                                                  ^
 DETAIL:  This would cause the generated column to depend on its own value.
 -- invalid reference
-CREATE TABLE gtest_err_3 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (c * 2) STORED);
+CREATE TABLE gtest_err_3 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (c * 2) VIRTUAL);
 ERROR:  column "c" does not exist
-LINE 1: ..._3 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (c * 2) STO...
+LINE 1: ..._3 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (c * 2) VIR...
                                                              ^
 -- generation expression must be immutable
-CREATE TABLE gtest_err_4 (a int PRIMARY KEY, b double precision GENERATED ALWAYS AS (random()) STORED);
+CREATE TABLE gtest_err_4 (a int PRIMARY KEY, b double precision GENERATED ALWAYS AS (random()) VIRTUAL);
 ERROR:  generation expression is not immutable
 -- ... but be sure that the immutability test is accurate
-CREATE TABLE gtest2 (a int, b text GENERATED ALWAYS AS (a || ' sec') STORED);
+CREATE TABLE gtest2 (a int, b text GENERATED ALWAYS AS (a || ' sec') VIRTUAL);
 DROP TABLE gtest2;
 -- cannot have default/identity and generated
-CREATE TABLE gtest_err_5a (a int PRIMARY KEY, b int DEFAULT 5 GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest_err_5a (a int PRIMARY KEY, b int DEFAULT 5 GENERATED ALWAYS AS (a * 2) VIRTUAL);
 ERROR:  both default and generation expression specified for column "b" of table "gtest_err_5a"
 LINE 1: ... gtest_err_5a (a int PRIMARY KEY, b int DEFAULT 5 GENERATED ...
                                                              ^
-CREATE TABLE gtest_err_5b (a int PRIMARY KEY, b int GENERATED ALWAYS AS identity GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest_err_5b (a int PRIMARY KEY, b int GENERATED ALWAYS AS identity GENERATED ALWAYS AS (a * 2) VIRTUAL);
 ERROR:  both identity and generation expression specified for column "b" of table "gtest_err_5b"
 LINE 1: ...t PRIMARY KEY, b int GENERATED ALWAYS AS identity GENERATED ...
                                                              ^
 -- reference to system column not allowed in generated column
 -- (except tableoid, which we test below)
-CREATE TABLE gtest_err_6a (a int PRIMARY KEY, b bool GENERATED ALWAYS AS (xmin <> 37) STORED);
+CREATE TABLE gtest_err_6a (a int PRIMARY KEY, b bool GENERATED ALWAYS AS (xmin <> 37) VIRTUAL);
 ERROR:  cannot use system column "xmin" in column generation expression
 LINE 1: ...a (a int PRIMARY KEY, b bool GENERATED ALWAYS AS (xmin <> 37...
                                                              ^
 -- various prohibited constructs
-CREATE TABLE gtest_err_7a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (avg(a)) STORED);
+CREATE TABLE gtest_err_7a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (avg(a)) VIRTUAL);
 ERROR:  aggregate functions are not allowed in column generation expressions
-LINE 1: ...7a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (avg(a)) ST...
+LINE 1: ...7a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (avg(a)) VI...
                                                              ^
-CREATE TABLE gtest_err_7b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (row_number() OVER (ORDER BY a)) STORED);
+CREATE TABLE gtest_err_7b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (row_number() OVER (ORDER BY a)) VIRTUAL);
 ERROR:  window functions are not allowed in column generation expressions
 LINE 1: ...7b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (row_number...
                                                              ^
-CREATE TABLE gtest_err_7c (a int PRIMARY KEY, b int GENERATED ALWAYS AS ((SELECT a)) STORED);
+CREATE TABLE gtest_err_7c (a int PRIMARY KEY, b int GENERATED ALWAYS AS ((SELECT a)) VIRTUAL);
 ERROR:  cannot use subquery in column generation expression
 LINE 1: ...7c (a int PRIMARY KEY, b int GENERATED ALWAYS AS ((SELECT a)...
                                                              ^
-CREATE TABLE gtest_err_7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generate_series(1, a)) STORED);
+CREATE TABLE gtest_err_7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generate_series(1, a)) VIRTUAL);
 ERROR:  set-returning functions are not allowed in column generation expressions
 LINE 1: ...7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generate_s...
                                                              ^
 -- GENERATED BY DEFAULT not allowed
-CREATE TABLE gtest_err_8 (a int PRIMARY KEY, b int GENERATED BY DEFAULT AS (a * 2) STORED);
+CREATE TABLE gtest_err_8 (a int PRIMARY KEY, b int GENERATED BY DEFAULT AS (a * 2) VIRTUAL);
 ERROR:  for a generated column, GENERATED ALWAYS must be specified
 LINE 1: ...E gtest_err_8 (a int PRIMARY KEY, b int GENERATED BY DEFAULT...
                                                              ^
@@ -153,16 +153,10 @@ SELECT a, b FROM gtest1 WHERE b = 4 ORDER BY a;
  2 | 4
 (1 row)
 
--- test that overflow error happens on write
+-- test that overflow error happens on read
 INSERT INTO gtest1 VALUES (2000000000);
-ERROR:  integer out of range
 SELECT * FROM gtest1;
- a | b 
----+---
- 2 | 4
- 1 | 2
-(2 rows)
-
+ERROR:  integer out of range
 DELETE FROM gtest1 WHERE a = 2000000000;
 -- test with joins
 CREATE TABLE gtestx (x int, y int);
@@ -203,8 +197,8 @@ CREATE TABLE gtestm (
   id int PRIMARY KEY,
   f1 int,
   f2 int,
-  f3 int GENERATED ALWAYS AS (f1 * 2) STORED,
-  f4 int GENERATED ALWAYS AS (f2 * 2) STORED
+  f3 int GENERATED ALWAYS AS (f1 * 2) VIRTUAL,
+  f4 int GENERATED ALWAYS AS (f2 * 2) VIRTUAL
 );
 INSERT INTO gtestm VALUES (1, 5, 100);
 MERGE INTO gtestm t USING (VALUES (1, 10), (2, 20)) v(id, f1) ON t.id = v.id
@@ -273,11 +267,11 @@ SELECT * FROM gtest1_1;
 (0 rows)
 
 \d gtest1_1
-                   Table "generated_stored_tests.gtest1_1"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
+               Table "generated_virtual_tests.gtest1_1"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           | not null | 
- b      | integer |           |          | generated always as (a * 2) stored
+ b      | integer |           |          | generated always as (a * 2)
 Inherits: gtest1
 
 INSERT INTO gtest1_1 VALUES (4);
@@ -296,12 +290,12 @@ SELECT * FROM gtest1;
 
 -- can't have generated column that is a child of normal column
 CREATE TABLE gtest_normal (a int, b int);
-CREATE TABLE gtest_normal_child (a int, b int GENERATED ALWAYS AS (a * 2) STORED) INHERITS (gtest_normal);  -- error
+CREATE TABLE gtest_normal_child (a int, b int GENERATED ALWAYS AS (a * 2) VIRTUAL) INHERITS (gtest_normal);  -- error
 NOTICE:  merging column "a" with inherited definition
 NOTICE:  merging column "b" with inherited definition
 ERROR:  child column "b" specifies generation expression
 HINT:  A child table column cannot be generated unless its parent column is.
-CREATE TABLE gtest_normal_child (a int, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest_normal_child (a int, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 ALTER TABLE gtest_normal_child INHERIT gtest_normal;  -- error
 ERROR:  column "b" in child table must not be a generated column
 DROP TABLE gtest_normal, gtest_normal_child;
@@ -312,23 +306,41 @@ ERROR:  column "b" inherits from generated column but specifies default
 CREATE TABLE gtestx (x int, b int GENERATED ALWAYS AS IDENTITY) INHERITS (gtest1);  -- error
 NOTICE:  merging column "b" with inherited definition
 ERROR:  column "b" inherits from generated column but specifies identity
-CREATE TABLE gtestx (x int, b int GENERATED ALWAYS AS (a * 22) STORED) INHERITS (gtest1);  -- ok, overrides parent
+CREATE TABLE gtestx (x int, b int GENERATED ALWAYS AS (a * 22) STORED) INHERITS (gtest1);  -- error
+NOTICE:  merging column "b" with inherited definition
+ERROR:  column "b" inherits from generated column of different kind
+CREATE TABLE gtestx (x int, b int GENERATED ALWAYS AS (a * 22) VIRTUAL) INHERITS (gtest1);  -- ok, overrides parent
 NOTICE:  merging column "b" with inherited definition
 \d+ gtestx
-                                        Table "generated_stored_tests.gtestx"
- Column |  Type   | Collation | Nullable |               Default               | Storage | Stats target | Description 
---------+---------+-----------+----------+-------------------------------------+---------+--------------+-------------
- a      | integer |           | not null |                                     | plain   |              | 
- b      | integer |           |          | generated always as (a * 22) stored | plain   |              | 
- x      | integer |           |          |                                     | plain   |              | 
+                                    Table "generated_virtual_tests.gtestx"
+ Column |  Type   | Collation | Nullable |           Default            | Storage | Stats target | Description 
+--------+---------+-----------+----------+------------------------------+---------+--------------+-------------
+ a      | integer |           | not null |                              | plain   |              | 
+ b      | integer |           |          | generated always as (a * 22) | plain   |              | 
+ x      | integer |           |          |                              | plain   |              | 
 Inherits: gtest1
 
+INSERT INTO gtestx (a, x) VALUES (11, 22);
+SELECT * FROM gtest1;
+ a  | b  
+----+----
+  3 |  6
+  4 |  8
+ 11 | 22
+(3 rows)
+
+SELECT * FROM gtestx;
+ a  |  b  | x  
+----+-----+----
+ 11 | 242 | 22
+(1 row)
+
 CREATE TABLE gtestxx_1 (a int NOT NULL, b int);
 ALTER TABLE gtestxx_1 INHERIT gtest1;  -- error
 ERROR:  column "b" in child table must be a generated column
-CREATE TABLE gtestxx_3 (a int NOT NULL, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtestxx_3 (a int NOT NULL, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 ALTER TABLE gtestxx_3 INHERIT gtest1;  -- ok
-CREATE TABLE gtestxx_4 (b int GENERATED ALWAYS AS (a * 2) STORED, a int NOT NULL);
+CREATE TABLE gtestxx_4 (b int GENERATED ALWAYS AS (a * 2) VIRTUAL, a int NOT NULL);
 ALTER TABLE gtestxx_4 INHERIT gtest1;  -- ok
 -- test multiple inheritance mismatches
 CREATE TABLE gtesty (x int, b int DEFAULT 55);
@@ -341,28 +353,28 @@ CREATE TABLE gtest1_y () INHERITS (gtest1, gtesty);  -- error
 NOTICE:  merging multiple inherited definitions of column "b"
 ERROR:  inherited column "b" has a generation conflict
 DROP TABLE gtesty;
-CREATE TABLE gtesty (x int, b int GENERATED ALWAYS AS (x * 22) STORED);
+CREATE TABLE gtesty (x int, b int GENERATED ALWAYS AS (x * 22) VIRTUAL);
 CREATE TABLE gtest1_y () INHERITS (gtest1, gtesty);  -- error
 NOTICE:  merging multiple inherited definitions of column "b"
 ERROR:  column "b" inherits conflicting generation expressions
 HINT:  To resolve the conflict, specify a generation expression explicitly.
-CREATE TABLE gtest1_y (b int GENERATED ALWAYS AS (x + 1) STORED) INHERITS (gtest1, gtesty);  -- ok
+CREATE TABLE gtest1_y (b int GENERATED ALWAYS AS (x + 1) VIRTUAL) INHERITS (gtest1, gtesty);  -- ok
 NOTICE:  merging multiple inherited definitions of column "b"
 NOTICE:  moving and merging column "b" with inherited definition
 DETAIL:  User-specified column moved to the position of the inherited column.
 \d gtest1_y
-                   Table "generated_stored_tests.gtest1_y"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
+               Table "generated_virtual_tests.gtest1_y"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           | not null | 
- b      | integer |           |          | generated always as (x + 1) stored
+ b      | integer |           |          | generated always as (x + 1)
  x      | integer |           |          | 
 Inherits: gtest1,
           gtesty
 
 -- test correct handling of GENERATED column that's only in child
 CREATE TABLE gtestp (f1 int);
-CREATE TABLE gtestc (f2 int GENERATED ALWAYS AS (f1+1) STORED) INHERITS(gtestp);
+CREATE TABLE gtestc (f2 int GENERATED ALWAYS AS (f1+1) VIRTUAL) INHERITS(gtestp);
 INSERT INTO gtestc values(42);
 TABLE gtestc;
  f1 | f2 
@@ -379,8 +391,8 @@ TABLE gtestc;
 
 DROP TABLE gtestp CASCADE;
 NOTICE:  drop cascades to table gtestc
--- test stored update
-CREATE TABLE gtest3 (a int, b int GENERATED ALWAYS AS (a * 3) STORED);
+-- test update XXX
+CREATE TABLE gtest3 (a int, b int GENERATED ALWAYS AS (a * 3) VIRTUAL);
 INSERT INTO gtest3 (a) VALUES (1), (2), (3), (NULL);
 SELECT * FROM gtest3 ORDER BY a;
  a | b 
@@ -401,7 +413,7 @@ SELECT * FROM gtest3 ORDER BY a;
     |   
 (4 rows)
 
-CREATE TABLE gtest3a (a text, b text GENERATED ALWAYS AS (a || '+' || a) STORED);
+CREATE TABLE gtest3a (a text, b text GENERATED ALWAYS AS (a || '+' || a) VIRTUAL);
 INSERT INTO gtest3a (a) VALUES ('a'), ('b'), ('c'), (NULL);
 SELECT * FROM gtest3a ORDER BY a;
  a |  b  
@@ -466,7 +478,7 @@ SELECT * FROM gtest3 ORDER BY a;
 (4 rows)
 
 -- null values
-CREATE TABLE gtest2 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (NULL) STORED);
+CREATE TABLE gtest2 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (NULL) VIRTUAL);
 INSERT INTO gtest2 VALUES (1);
 SELECT * FROM gtest2;
  a | b 
@@ -475,7 +487,7 @@ SELECT * FROM gtest2;
 (1 row)
 
 -- simple column reference for varlena types
-CREATE TABLE gtest_varlena (a varchar, b varchar GENERATED ALWAYS AS (a) STORED);
+CREATE TABLE gtest_varlena (a varchar, b varchar GENERATED ALWAYS AS (a) VIRTUAL);
 INSERT INTO gtest_varlena (a) VALUES('01234567890123456789');
 INSERT INTO gtest_varlena (a) VALUES(NULL);
 SELECT * FROM gtest_varlena ORDER BY a;
@@ -490,7 +502,7 @@ DROP TABLE gtest_varlena;
 CREATE TYPE double_int as (a int, b int);
 CREATE TABLE gtest4 (
     a int,
-    b double_int GENERATED ALWAYS AS ((a * 2, a * 3)) STORED
+    b double_int GENERATED ALWAYS AS ((a * 2, a * 3)) VIRTUAL
 );
 INSERT INTO gtest4 VALUES (1), (6);
 SELECT * FROM gtest4;
@@ -505,11 +517,11 @@ DROP TYPE double_int;
 -- using tableoid is allowed
 CREATE TABLE gtest_tableoid (
   a int PRIMARY KEY,
-  b bool GENERATED ALWAYS AS (tableoid = 'gtest_tableoid'::regclass) STORED
+  b bool GENERATED ALWAYS AS (tableoid = 'gtest_tableoid'::regclass) VIRTUAL
 );
 INSERT INTO gtest_tableoid VALUES (1), (2);
 ALTER TABLE gtest_tableoid ADD COLUMN
-  c regclass GENERATED ALWAYS AS (tableoid) STORED;
+  c regclass GENERATED ALWAYS AS (tableoid) VIRTUAL;
 SELECT * FROM gtest_tableoid;
  a | b |       c        
 ---+---+----------------
@@ -518,7 +530,7 @@ SELECT * FROM gtest_tableoid;
 (2 rows)
 
 -- drop column behavior
-CREATE TABLE gtest10 (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (b * 2) STORED);
+CREATE TABLE gtest10 (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (b * 2) VIRTUAL);
 ALTER TABLE gtest10 DROP COLUMN b;  -- fails
 ERROR:  cannot drop column b of table gtest10 because other objects depend on it
 DETAIL:  column c of table gtest10 depends on column b of table gtest10
@@ -526,30 +538,31 @@ HINT:  Use DROP ... CASCADE to drop the dependent objects too.
 ALTER TABLE gtest10 DROP COLUMN b CASCADE;  -- drops c too
 NOTICE:  drop cascades to column c of table gtest10
 \d gtest10
-      Table "generated_stored_tests.gtest10"
+      Table "generated_virtual_tests.gtest10"
  Column |  Type   | Collation | Nullable | Default 
 --------+---------+-----------+----------+---------
  a      | integer |           | not null | 
 Indexes:
     "gtest10_pkey" PRIMARY KEY, btree (a)
 
-CREATE TABLE gtest10a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest10a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 ALTER TABLE gtest10a DROP COLUMN b;
 INSERT INTO gtest10a (a) VALUES (1);
 -- privileges
 CREATE USER regress_user11;
-CREATE TABLE gtest11s (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (b * 2) STORED);
-INSERT INTO gtest11s VALUES (1, 10), (2, 20);
-GRANT SELECT (a, c) ON gtest11s TO regress_user11;
+CREATE TABLE gtest11v (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (b * 2) VIRTUAL);
+INSERT INTO gtest11v VALUES (1, 10), (2, 20);
+GRANT SELECT (a, c) ON gtest11v TO regress_user11;
 CREATE FUNCTION gf1(a int) RETURNS int AS $$ SELECT a * 3 $$ IMMUTABLE LANGUAGE SQL;
 REVOKE ALL ON FUNCTION gf1(int) FROM PUBLIC;
-CREATE TABLE gtest12s (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (gf1(b)) STORED);
-INSERT INTO gtest12s VALUES (1, 10), (2, 20);
+CREATE TABLE gtest12v (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (gf1(b)) VIRTUAL);
+INSERT INTO gtest12v VALUES (1, 10), (2, 20);
 GRANT SELECT (a, c) ON gtest12s TO regress_user11;
+ERROR:  relation "gtest12s" does not exist
 SET ROLE regress_user11;
-SELECT a, b FROM gtest11s;  -- not allowed
-ERROR:  permission denied for table gtest11s
-SELECT a, c FROM gtest11s;  -- allowed
+SELECT a, b FROM gtest11v;  -- not allowed
+ERROR:  permission denied for table gtest11v
+SELECT a, c FROM gtest11v;  -- allowed
  a | c  
 ---+----
  1 | 20
@@ -558,231 +571,139 @@ SELECT a, c FROM gtest11s;  -- allowed
 
 SELECT gf1(10);  -- not allowed
 ERROR:  permission denied for function gf1
-SELECT a, c FROM gtest12s;  -- allowed
- a | c  
----+----
- 1 | 30
- 2 | 60
-(2 rows)
-
+SELECT a, c FROM gtest12v;  -- not allowed; TODO: ought to be allowed
+ERROR:  permission denied for table gtest12v
 RESET ROLE;
 DROP FUNCTION gf1(int);  -- fail
 ERROR:  cannot drop function gf1(integer) because other objects depend on it
-DETAIL:  column c of table gtest12s depends on function gf1(integer)
+DETAIL:  column c of table gtest12v depends on function gf1(integer)
 HINT:  Use DROP ... CASCADE to drop the dependent objects too.
-DROP TABLE gtest11s, gtest12s;
+DROP TABLE gtest11v, gtest12v;
 DROP FUNCTION gf1(int);
 DROP USER regress_user11;
 -- check constraints
-CREATE TABLE gtest20 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED CHECK (b < 50));
+CREATE TABLE gtest20 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL CHECK (b < 50));
 INSERT INTO gtest20 (a) VALUES (10);  -- ok
 INSERT INTO gtest20 (a) VALUES (30);  -- violates constraint
 ERROR:  new row for relation "gtest20" violates check constraint "gtest20_b_check"
-DETAIL:  Failing row contains (30, 60).
+DETAIL:  Failing row contains (30, virtual).
 ALTER TABLE gtest20 ALTER COLUMN b SET EXPRESSION AS (a * 100);  -- violates constraint
-ERROR:  check constraint "gtest20_b_check" of relation "gtest20" is violated by some row
+ERROR:  ALTER TABLE / SET EXPRESSION is not supported for virtual generated columns
+DETAIL:  Column "b" of relation "gtest20" is a virtual generated column.
 ALTER TABLE gtest20 ALTER COLUMN b SET EXPRESSION AS (a * 3);  -- ok
-CREATE TABLE gtest20a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
+ERROR:  ALTER TABLE / SET EXPRESSION is not supported for virtual generated columns
+DETAIL:  Column "b" of relation "gtest20" is a virtual generated column.
+CREATE TABLE gtest20a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 INSERT INTO gtest20a (a) VALUES (10);
 INSERT INTO gtest20a (a) VALUES (30);
 ALTER TABLE gtest20a ADD CHECK (b < 50);  -- fails on existing row
 ERROR:  check constraint "gtest20a_b_check" of relation "gtest20a" is violated by some row
-CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 INSERT INTO gtest20b (a) VALUES (10);
 INSERT INTO gtest20b (a) VALUES (30);
 ALTER TABLE gtest20b ADD CONSTRAINT chk CHECK (b < 50) NOT VALID;
 ALTER TABLE gtest20b VALIDATE CONSTRAINT chk;  -- fails on existing row
 ERROR:  check constraint "chk" of relation "gtest20b" is violated by some row
--- not-null constraints
-CREATE TABLE gtest21a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (nullif(a, 0)) STORED NOT NULL);
-INSERT INTO gtest21a (a) VALUES (1);  -- ok
-INSERT INTO gtest21a (a) VALUES (0);  -- violates constraint
-ERROR:  null value in column "b" of relation "gtest21a" violates not-null constraint
-DETAIL:  Failing row contains (0, null).
-CREATE TABLE gtest21b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (nullif(a, 0)) STORED);
+-- not-null constraints (currently not supported)
+CREATE TABLE gtest21a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (nullif(a, 0)) VIRTUAL NOT NULL);
+ERROR:  not-null constraints are not supported on virtual generated columns
+--INSERT INTO gtest21a (a) VALUES (1);  -- ok
+--INSERT INTO gtest21a (a) VALUES (0);  -- violates constraint
+CREATE TABLE gtest21b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (nullif(a, 0)) VIRTUAL);
 ALTER TABLE gtest21b ALTER COLUMN b SET NOT NULL;
-INSERT INTO gtest21b (a) VALUES (1);  -- ok
-INSERT INTO gtest21b (a) VALUES (0);  -- violates constraint
-ERROR:  null value in column "b" of relation "gtest21b" violates not-null constraint
-DETAIL:  Failing row contains (0, null).
+ERROR:  not-null constraints are not supported on virtual generated columns
+DETAIL:  Column "b" of relation "gtest21b" is a virtual generated column.
+--INSERT INTO gtest21b (a) VALUES (1);  -- ok
+--INSERT INTO gtest21b (a) VALUES (0);  -- violates constraint
 ALTER TABLE gtest21b ALTER COLUMN b DROP NOT NULL;
-INSERT INTO gtest21b (a) VALUES (0);  -- ok now
+--INSERT INTO gtest21b (a) VALUES (0);  -- ok now
 -- index constraints
-CREATE TABLE gtest22a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a / 2) STORED UNIQUE);
-INSERT INTO gtest22a VALUES (2);
-INSERT INTO gtest22a VALUES (3);
-ERROR:  duplicate key value violates unique constraint "gtest22a_b_key"
-DETAIL:  Key (b)=(1) already exists.
-INSERT INTO gtest22a VALUES (4);
-CREATE TABLE gtest22b (a int, b int GENERATED ALWAYS AS (a / 2) STORED, PRIMARY KEY (a, b));
-INSERT INTO gtest22b VALUES (2);
-INSERT INTO gtest22b VALUES (2);
-ERROR:  duplicate key value violates unique constraint "gtest22b_pkey"
-DETAIL:  Key (a, b)=(2, 1) already exists.
+CREATE TABLE gtest22a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a / 2) VIRTUAL UNIQUE);
+ERROR:  index creation on virtual generated columns is not supported
+--INSERT INTO gtest22a VALUES (2);
+--INSERT INTO gtest22a VALUES (3);
+--INSERT INTO gtest22a VALUES (4);
+CREATE TABLE gtest22b (a int, b int GENERATED ALWAYS AS (a / 2) VIRTUAL, PRIMARY KEY (a, b));
+ERROR:  index creation on virtual generated columns is not supported
+--INSERT INTO gtest22b VALUES (2);
+--INSERT INTO gtest22b VALUES (2);
 -- indexes
-CREATE TABLE gtest22c (a int, b int GENERATED ALWAYS AS (a * 2) STORED);
-CREATE INDEX gtest22c_b_idx ON gtest22c (b);
-CREATE INDEX gtest22c_expr_idx ON gtest22c ((b * 3));
-CREATE INDEX gtest22c_pred_idx ON gtest22c (a) WHERE b > 0;
-\d gtest22c
-                   Table "generated_stored_tests.gtest22c"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
- a      | integer |           |          | 
- b      | integer |           |          | generated always as (a * 2) stored
-Indexes:
-    "gtest22c_b_idx" btree (b)
-    "gtest22c_expr_idx" btree ((b * 3))
-    "gtest22c_pred_idx" btree (a) WHERE b > 0
-
-INSERT INTO gtest22c VALUES (1), (2), (3);
-SET enable_seqscan TO off;
-SET enable_bitmapscan TO off;
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b = 4;
-                 QUERY PLAN                  
----------------------------------------------
- Index Scan using gtest22c_b_idx on gtest22c
-   Index Cond: (b = 4)
-(2 rows)
-
-SELECT * FROM gtest22c WHERE b = 4;
- a | b 
----+---
- 2 | 4
-(1 row)
-
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b * 3 = 6;
-                   QUERY PLAN                   
-------------------------------------------------
- Index Scan using gtest22c_expr_idx on gtest22c
-   Index Cond: ((b * 3) = 6)
-(2 rows)
-
-SELECT * FROM gtest22c WHERE b * 3 = 6;
- a | b 
----+---
- 1 | 2
-(1 row)
-
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
-                   QUERY PLAN                   
-------------------------------------------------
- Index Scan using gtest22c_pred_idx on gtest22c
-   Index Cond: (a = 1)
-(2 rows)
-
-SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
- a | b 
----+---
- 1 | 2
-(1 row)
-
-ALTER TABLE gtest22c ALTER COLUMN b SET EXPRESSION AS (a * 4);
-ANALYZE gtest22c;
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b = 8;
-                 QUERY PLAN                  
----------------------------------------------
- Index Scan using gtest22c_b_idx on gtest22c
-   Index Cond: (b = 8)
-(2 rows)
-
-SELECT * FROM gtest22c WHERE b = 8;
- a | b 
----+---
- 2 | 8
-(1 row)
-
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b * 3 = 12;
-                   QUERY PLAN                   
-------------------------------------------------
- Index Scan using gtest22c_expr_idx on gtest22c
-   Index Cond: ((b * 3) = 12)
-(2 rows)
-
-SELECT * FROM gtest22c WHERE b * 3 = 12;
- a | b 
----+---
- 1 | 4
-(1 row)
-
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
-                   QUERY PLAN                   
-------------------------------------------------
- Index Scan using gtest22c_pred_idx on gtest22c
-   Index Cond: (a = 1)
-(2 rows)
-
-SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
- a | b 
----+---
- 1 | 4
-(1 row)
-
-RESET enable_seqscan;
-RESET enable_bitmapscan;
+CREATE TABLE gtest22c (a int, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
+--CREATE INDEX gtest22c_b_idx ON gtest22c (b);
+--CREATE INDEX gtest22c_expr_idx ON gtest22c ((b * 3));
+--CREATE INDEX gtest22c_pred_idx ON gtest22c (a) WHERE b > 0;
+--\d gtest22c
+--INSERT INTO gtest22c VALUES (1), (2), (3);
+--SET enable_seqscan TO off;
+--SET enable_bitmapscan TO off;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b = 4;
+--SELECT * FROM gtest22c WHERE b = 4;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b * 3 = 6;
+--SELECT * FROM gtest22c WHERE b * 3 = 6;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
+--SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
+--ALTER TABLE gtest22c ALTER COLUMN b SET EXPRESSION AS (a * 4);
+--ANALYZE gtest22c;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b = 8;
+--SELECT * FROM gtest22c WHERE b = 8;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b * 3 = 12;
+--SELECT * FROM gtest22c WHERE b * 3 = 12;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
+--SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
+--RESET enable_seqscan;
+--RESET enable_bitmapscan;
 -- foreign keys
 CREATE TABLE gtest23a (x int PRIMARY KEY, y int);
-INSERT INTO gtest23a VALUES (1, 11), (2, 22), (3, 33);
-CREATE TABLE gtest23x (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED REFERENCES gtest23a (x) ON UPDATE CASCADE);  -- error
+--INSERT INTO gtest23a VALUES (1, 11), (2, 22), (3, 33);
+CREATE TABLE gtest23x (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL REFERENCES gtest23a (x) ON UPDATE CASCADE);  -- error
 ERROR:  invalid ON UPDATE action for foreign key constraint containing generated column
-CREATE TABLE gtest23x (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED REFERENCES gtest23a (x) ON DELETE SET NULL);  -- error
+CREATE TABLE gtest23x (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL REFERENCES gtest23a (x) ON DELETE SET NULL);  -- error
 ERROR:  invalid ON DELETE action for foreign key constraint containing generated column
-CREATE TABLE gtest23b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED REFERENCES gtest23a (x));
-\d gtest23b
-                   Table "generated_stored_tests.gtest23b"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
- a      | integer |           | not null | 
- b      | integer |           |          | generated always as (a * 2) stored
-Indexes:
-    "gtest23b_pkey" PRIMARY KEY, btree (a)
-Foreign-key constraints:
-    "gtest23b_b_fkey" FOREIGN KEY (b) REFERENCES gtest23a(x)
-
-INSERT INTO gtest23b VALUES (1);  -- ok
-INSERT INTO gtest23b VALUES (5);  -- error
-ERROR:  insert or update on table "gtest23b" violates foreign key constraint "gtest23b_b_fkey"
-DETAIL:  Key (b)=(10) is not present in table "gtest23a".
-ALTER TABLE gtest23b ALTER COLUMN b SET EXPRESSION AS (a * 5); -- error
-ERROR:  insert or update on table "gtest23b" violates foreign key constraint "gtest23b_b_fkey"
-DETAIL:  Key (b)=(5) is not present in table "gtest23a".
-ALTER TABLE gtest23b ALTER COLUMN b SET EXPRESSION AS (a * 1); -- ok
-DROP TABLE gtest23b;
-DROP TABLE gtest23a;
-CREATE TABLE gtest23p (x int, y int GENERATED ALWAYS AS (x * 2) STORED, PRIMARY KEY (y));
-INSERT INTO gtest23p VALUES (1), (2), (3);
+CREATE TABLE gtest23b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL REFERENCES gtest23a (x));
+ERROR:  foreign key constraints on virtual generated columns are not supported
+--\d gtest23b
+--INSERT INTO gtest23b VALUES (1);  -- ok
+--INSERT INTO gtest23b VALUES (5);  -- error
+--ALTER TABLE gtest23b ALTER COLUMN b SET EXPRESSION AS (a * 5); -- error
+--ALTER TABLE gtest23b ALTER COLUMN b SET EXPRESSION AS (a * 1); -- ok
+--DROP TABLE gtest23b;
+--DROP TABLE gtest23a;
+CREATE TABLE gtest23p (x int, y int GENERATED ALWAYS AS (x * 2) VIRTUAL, PRIMARY KEY (y));
+ERROR:  index creation on virtual generated columns is not supported
+--INSERT INTO gtest23p VALUES (1), (2), (3);
 CREATE TABLE gtest23q (a int PRIMARY KEY, b int REFERENCES gtest23p (y));
-INSERT INTO gtest23q VALUES (1, 2);  -- ok
-INSERT INTO gtest23q VALUES (2, 5);  -- error
-ERROR:  insert or update on table "gtest23q" violates foreign key constraint "gtest23q_b_fkey"
-DETAIL:  Key (b)=(5) is not present in table "gtest23p".
+ERROR:  relation "gtest23p" does not exist
+--INSERT INTO gtest23q VALUES (1, 2);  -- ok
+--INSERT INTO gtest23q VALUES (2, 5);  -- error
 -- domains
 CREATE DOMAIN gtestdomain1 AS int CHECK (VALUE < 10);
-CREATE TABLE gtest24 (a int PRIMARY KEY, b gtestdomain1 GENERATED ALWAYS AS (a * 2) STORED);
-INSERT INTO gtest24 (a) VALUES (4);  -- ok
-INSERT INTO gtest24 (a) VALUES (6);  -- error
-ERROR:  value for domain gtestdomain1 violates check constraint "gtestdomain1_check"
+CREATE TABLE gtest24 (a int PRIMARY KEY, b gtestdomain1 GENERATED ALWAYS AS (a * 2) VIRTUAL);
+ERROR:  virtual generated column "b" cannot have a domain type
+LINE 1: CREATE TABLE gtest24 (a int PRIMARY KEY, b gtestdomain1 GENE...
+                                                 ^
+--INSERT INTO gtest24 (a) VALUES (4);  -- ok
+--INSERT INTO gtest24 (a) VALUES (6);  -- error
 -- typed tables (currently not supported)
 CREATE TYPE gtest_type AS (f1 integer, f2 text, f3 bigint);
-CREATE TABLE gtest28 OF gtest_type (f1 WITH OPTIONS GENERATED ALWAYS AS (f2 *2) STORED);
+CREATE TABLE gtest28 OF gtest_type (f1 WITH OPTIONS GENERATED ALWAYS AS (f2 *2) VIRTUAL);
 ERROR:  generated columns are not supported on typed tables
 DROP TYPE gtest_type CASCADE;
 -- partitioning cases
 CREATE TABLE gtest_parent (f1 date NOT NULL, f2 bigint, f3 bigint) PARTITION BY RANGE (f1);
 CREATE TABLE gtest_child PARTITION OF gtest_parent (
-    f3 WITH OPTIONS GENERATED ALWAYS AS (f2 * 2) STORED
+    f3 WITH OPTIONS GENERATED ALWAYS AS (f2 * 2) VIRTUAL
 ) FOR VALUES FROM ('2016-07-01') TO ('2016-08-01'); -- error
 ERROR:  child column "f3" specifies generation expression
 HINT:  A child table column cannot be generated unless its parent column is.
-CREATE TABLE gtest_child (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) STORED);
+CREATE TABLE gtest_child (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) VIRTUAL);
 ALTER TABLE gtest_parent ATTACH PARTITION gtest_child FOR VALUES FROM ('2016-07-01') TO ('2016-08-01'); -- error
 ERROR:  column "f3" in child table must not be a generated column
 DROP TABLE gtest_parent, gtest_child;
-CREATE TABLE gtest_parent (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) STORED) PARTITION BY RANGE (f1);
+CREATE TABLE gtest_parent (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) VIRTUAL) PARTITION BY RANGE (f1);
 CREATE TABLE gtest_child PARTITION OF gtest_parent
   FOR VALUES FROM ('2016-07-01') TO ('2016-08-01');  -- inherits gen expr
 CREATE TABLE gtest_child2 PARTITION OF gtest_parent (
-    f3 WITH OPTIONS GENERATED ALWAYS AS (f2 * 22) STORED  -- overrides gen expr
+    f3 WITH OPTIONS GENERATED ALWAYS AS (f2 * 22) VIRTUAL  -- overrides gen expr
 ) FOR VALUES FROM ('2016-08-01') TO ('2016-09-01');
 CREATE TABLE gtest_child3 PARTITION OF gtest_parent (
     f3 DEFAULT 42  -- error
@@ -792,6 +713,10 @@ CREATE TABLE gtest_child3 PARTITION OF gtest_parent (
     f3 WITH OPTIONS GENERATED ALWAYS AS IDENTITY  -- error
 ) FOR VALUES FROM ('2016-09-01') TO ('2016-10-01');
 ERROR:  identity columns are not supported on partitions
+CREATE TABLE gtest_child3 PARTITION OF gtest_parent (
+    f3 GENERATED ALWAYS AS (f2 * 2) STORED  -- error
+) FOR VALUES FROM ('2016-09-01') TO ('2016-10-01');
+ERROR:  column "f3" inherits from generated column of different kind
 CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint);
 ALTER TABLE gtest_parent ATTACH PARTITION gtest_child3 FOR VALUES FROM ('2016-09-01') TO ('2016-10-01'); -- error
 ERROR:  column "f3" in child table must be a generated column
@@ -805,33 +730,33 @@ ALTER TABLE gtest_parent ATTACH PARTITION gtest_child3 FOR VALUES FROM ('2016-09
 ERROR:  table "gtest_child3" being attached contains an identity column "f3"
 DETAIL:  The new partition may not contain an identity column.
 DROP TABLE gtest_child3;
-CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 33) STORED);
+CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 33) VIRTUAL);
 ALTER TABLE gtest_parent ATTACH PARTITION gtest_child3 FOR VALUES FROM ('2016-09-01') TO ('2016-10-01');
 \d gtest_child
-                  Table "generated_stored_tests.gtest_child"
- Column |  Type  | Collation | Nullable |               Default               
---------+--------+-----------+----------+-------------------------------------
+              Table "generated_virtual_tests.gtest_child"
+ Column |  Type  | Collation | Nullable |           Default            
+--------+--------+-----------+----------+------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 2) stored
+ f3     | bigint |           |          | generated always as (f2 * 2)
 Partition of: gtest_parent FOR VALUES FROM ('07-01-2016') TO ('08-01-2016')
 
 \d gtest_child2
-                  Table "generated_stored_tests.gtest_child2"
- Column |  Type  | Collation | Nullable |               Default                
---------+--------+-----------+----------+--------------------------------------
+              Table "generated_virtual_tests.gtest_child2"
+ Column |  Type  | Collation | Nullable |            Default            
+--------+--------+-----------+----------+-------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 22) stored
+ f3     | bigint |           |          | generated always as (f2 * 22)
 Partition of: gtest_parent FOR VALUES FROM ('08-01-2016') TO ('09-01-2016')
 
 \d gtest_child3
-                  Table "generated_stored_tests.gtest_child3"
- Column |  Type  | Collation | Nullable |               Default                
---------+--------+-----------+----------+--------------------------------------
+              Table "generated_virtual_tests.gtest_child3"
+ Column |  Type  | Collation | Nullable |            Default            
+--------+--------+-----------+----------+-------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 33) stored
+ f3     | bigint |           |          | generated always as (f2 * 33)
 Partition of: gtest_parent FOR VALUES FROM ('09-01-2016') TO ('10-01-2016')
 
 INSERT INTO gtest_parent (f1, f2) VALUES ('2016-07-15', 1);
@@ -842,7 +767,7 @@ SELECT tableoid::regclass, * FROM gtest_parent ORDER BY 1, 2, 3;
 --------------+------------+----+----
  gtest_child  | 07-15-2016 |  1 |  2
  gtest_child  | 07-15-2016 |  2 |  4
- gtest_child2 | 08-15-2016 |  3 | 66
+ gtest_child2 | 08-15-2016 |  3 |  6
 (3 rows)
 
 UPDATE gtest_parent SET f1 = f1 + 60 WHERE f2 = 1;
@@ -850,95 +775,101 @@ SELECT tableoid::regclass, * FROM gtest_parent ORDER BY 1, 2, 3;
    tableoid   |     f1     | f2 | f3 
 --------------+------------+----+----
  gtest_child  | 07-15-2016 |  2 |  4
- gtest_child2 | 08-15-2016 |  3 | 66
- gtest_child3 | 09-13-2016 |  1 | 33
+ gtest_child2 | 08-15-2016 |  3 |  6
+ gtest_child3 | 09-13-2016 |  1 |  2
 (3 rows)
 
 -- alter only parent's and one child's generation expression
 ALTER TABLE ONLY gtest_parent ALTER COLUMN f3 SET EXPRESSION AS (f2 * 4);
+ERROR:  ALTER TABLE / SET EXPRESSION is not supported for virtual generated columns
+DETAIL:  Column "f3" of relation "gtest_parent" is a virtual generated column.
 ALTER TABLE gtest_child ALTER COLUMN f3 SET EXPRESSION AS (f2 * 10);
+ERROR:  ALTER TABLE / SET EXPRESSION is not supported for virtual generated columns
+DETAIL:  Column "f3" of relation "gtest_child" is a virtual generated column.
 \d gtest_parent
-           Partitioned table "generated_stored_tests.gtest_parent"
- Column |  Type  | Collation | Nullable |               Default               
---------+--------+-----------+----------+-------------------------------------
+       Partitioned table "generated_virtual_tests.gtest_parent"
+ Column |  Type  | Collation | Nullable |           Default            
+--------+--------+-----------+----------+------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 4) stored
+ f3     | bigint |           |          | generated always as (f2 * 2)
 Partition key: RANGE (f1)
 Number of partitions: 3 (Use \d+ to list them.)
 
 \d gtest_child
-                  Table "generated_stored_tests.gtest_child"
- Column |  Type  | Collation | Nullable |               Default                
---------+--------+-----------+----------+--------------------------------------
+              Table "generated_virtual_tests.gtest_child"
+ Column |  Type  | Collation | Nullable |           Default            
+--------+--------+-----------+----------+------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 10) stored
+ f3     | bigint |           |          | generated always as (f2 * 2)
 Partition of: gtest_parent FOR VALUES FROM ('07-01-2016') TO ('08-01-2016')
 
 \d gtest_child2
-                  Table "generated_stored_tests.gtest_child2"
- Column |  Type  | Collation | Nullable |               Default                
---------+--------+-----------+----------+--------------------------------------
+              Table "generated_virtual_tests.gtest_child2"
+ Column |  Type  | Collation | Nullable |            Default            
+--------+--------+-----------+----------+-------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 22) stored
+ f3     | bigint |           |          | generated always as (f2 * 22)
 Partition of: gtest_parent FOR VALUES FROM ('08-01-2016') TO ('09-01-2016')
 
 \d gtest_child3
-                  Table "generated_stored_tests.gtest_child3"
- Column |  Type  | Collation | Nullable |               Default                
---------+--------+-----------+----------+--------------------------------------
+              Table "generated_virtual_tests.gtest_child3"
+ Column |  Type  | Collation | Nullable |            Default            
+--------+--------+-----------+----------+-------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 33) stored
+ f3     | bigint |           |          | generated always as (f2 * 33)
 Partition of: gtest_parent FOR VALUES FROM ('09-01-2016') TO ('10-01-2016')
 
 SELECT tableoid::regclass, * FROM gtest_parent ORDER BY 1, 2, 3;
    tableoid   |     f1     | f2 | f3 
 --------------+------------+----+----
- gtest_child  | 07-15-2016 |  2 | 20
- gtest_child2 | 08-15-2016 |  3 | 66
- gtest_child3 | 09-13-2016 |  1 | 33
+ gtest_child  | 07-15-2016 |  2 |  4
+ gtest_child2 | 08-15-2016 |  3 |  6
+ gtest_child3 | 09-13-2016 |  1 |  2
 (3 rows)
 
 -- alter generation expression of parent and all its children altogether
 ALTER TABLE gtest_parent ALTER COLUMN f3 SET EXPRESSION AS (f2 * 2);
+ERROR:  ALTER TABLE / SET EXPRESSION is not supported for virtual generated columns
+DETAIL:  Column "f3" of relation "gtest_parent" is a virtual generated column.
 \d gtest_parent
-           Partitioned table "generated_stored_tests.gtest_parent"
- Column |  Type  | Collation | Nullable |               Default               
---------+--------+-----------+----------+-------------------------------------
+       Partitioned table "generated_virtual_tests.gtest_parent"
+ Column |  Type  | Collation | Nullable |           Default            
+--------+--------+-----------+----------+------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 2) stored
+ f3     | bigint |           |          | generated always as (f2 * 2)
 Partition key: RANGE (f1)
 Number of partitions: 3 (Use \d+ to list them.)
 
 \d gtest_child
-                  Table "generated_stored_tests.gtest_child"
- Column |  Type  | Collation | Nullable |               Default               
---------+--------+-----------+----------+-------------------------------------
+              Table "generated_virtual_tests.gtest_child"
+ Column |  Type  | Collation | Nullable |           Default            
+--------+--------+-----------+----------+------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 2) stored
+ f3     | bigint |           |          | generated always as (f2 * 2)
 Partition of: gtest_parent FOR VALUES FROM ('07-01-2016') TO ('08-01-2016')
 
 \d gtest_child2
-                 Table "generated_stored_tests.gtest_child2"
- Column |  Type  | Collation | Nullable |               Default               
---------+--------+-----------+----------+-------------------------------------
+              Table "generated_virtual_tests.gtest_child2"
+ Column |  Type  | Collation | Nullable |            Default            
+--------+--------+-----------+----------+-------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 2) stored
+ f3     | bigint |           |          | generated always as (f2 * 22)
 Partition of: gtest_parent FOR VALUES FROM ('08-01-2016') TO ('09-01-2016')
 
 \d gtest_child3
-                 Table "generated_stored_tests.gtest_child3"
- Column |  Type  | Collation | Nullable |               Default               
---------+--------+-----------+----------+-------------------------------------
+              Table "generated_virtual_tests.gtest_child3"
+ Column |  Type  | Collation | Nullable |            Default            
+--------+--------+-----------+----------+-------------------------------
  f1     | date   |           | not null | 
  f2     | bigint |           |          | 
- f3     | bigint |           |          | generated always as (f2 * 2) stored
+ f3     | bigint |           |          | generated always as (f2 * 33)
 Partition of: gtest_parent FOR VALUES FROM ('09-01-2016') TO ('10-01-2016')
 
 SELECT tableoid::regclass, * FROM gtest_parent ORDER BY 1, 2, 3;
@@ -951,54 +882,54 @@ SELECT tableoid::regclass, * FROM gtest_parent ORDER BY 1, 2, 3;
 
 -- we leave these tables around for purposes of testing dump/reload/upgrade
 -- generated columns in partition key (not allowed)
-CREATE TABLE gtest_part_key (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) STORED) PARTITION BY RANGE (f3);
+CREATE TABLE gtest_part_key (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) VIRTUAL) PARTITION BY RANGE (f3);
 ERROR:  cannot use generated column in partition key
-LINE 1: ...ENERATED ALWAYS AS (f2 * 2) STORED) PARTITION BY RANGE (f3);
+LINE 1: ...NERATED ALWAYS AS (f2 * 2) VIRTUAL) PARTITION BY RANGE (f3);
                                                                    ^
 DETAIL:  Column "f3" is a generated column.
-CREATE TABLE gtest_part_key (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) STORED) PARTITION BY RANGE ((f3 * 3));
+CREATE TABLE gtest_part_key (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) VIRTUAL) PARTITION BY RANGE ((f3 * 3));
 ERROR:  cannot use generated column in partition key
-LINE 1: ...ED ALWAYS AS (f2 * 2) STORED) PARTITION BY RANGE ((f3 * 3));
+LINE 1: ...D ALWAYS AS (f2 * 2) VIRTUAL) PARTITION BY RANGE ((f3 * 3));
                                                              ^
 DETAIL:  Column "f3" is a generated column.
 -- ALTER TABLE ... ADD COLUMN
 CREATE TABLE gtest25 (a int PRIMARY KEY);
 INSERT INTO gtest25 VALUES (3), (4);
-ALTER TABLE gtest25 ADD COLUMN b int GENERATED ALWAYS AS (a * 2) STORED, ALTER COLUMN b SET EXPRESSION AS (a * 3);
+ALTER TABLE gtest25 ADD COLUMN b int GENERATED ALWAYS AS (a * 2) VIRTUAL, ALTER COLUMN b SET EXPRESSION AS (a * 3);
+ERROR:  ALTER TABLE / SET EXPRESSION is not supported for virtual generated columns
+DETAIL:  Column "b" of relation "gtest25" is a virtual generated column.
 SELECT * FROM gtest25 ORDER BY a;
- a | b  
----+----
- 3 |  9
- 4 | 12
+ a 
+---
+ 3
+ 4
 (2 rows)
 
-ALTER TABLE gtest25 ADD COLUMN x int GENERATED ALWAYS AS (b * 4) STORED;  -- error
-ERROR:  cannot use generated column "b" in column generation expression
-DETAIL:  A generated column cannot reference another generated column.
-ALTER TABLE gtest25 ADD COLUMN x int GENERATED ALWAYS AS (z * 4) STORED;  -- error
+ALTER TABLE gtest25 ADD COLUMN x int GENERATED ALWAYS AS (b * 4) VIRTUAL;  -- error
+ERROR:  column "b" does not exist
+ALTER TABLE gtest25 ADD COLUMN x int GENERATED ALWAYS AS (z * 4) VIRTUAL;  -- error
 ERROR:  column "z" does not exist
 ALTER TABLE gtest25 ADD COLUMN c int DEFAULT 42,
-  ADD COLUMN x int GENERATED ALWAYS AS (c * 4) STORED;
+  ADD COLUMN x int GENERATED ALWAYS AS (c * 4) VIRTUAL;
 ALTER TABLE gtest25 ADD COLUMN d int DEFAULT 101;
 ALTER TABLE gtest25 ALTER COLUMN d SET DATA TYPE float8,
-  ADD COLUMN y float8 GENERATED ALWAYS AS (d * 4) STORED;
+  ADD COLUMN y float8 GENERATED ALWAYS AS (d * 4) VIRTUAL;
 SELECT * FROM gtest25 ORDER BY a;
- a | b  | c  |  x  |  d  |  y  
----+----+----+-----+-----+-----
- 3 |  9 | 42 | 168 | 101 | 404
- 4 | 12 | 42 | 168 | 101 | 404
+ a | c  |  x  |  d  |  y  
+---+----+-----+-----+-----
+ 3 | 42 | 168 | 101 | 404
+ 4 | 42 | 168 | 101 | 404
 (2 rows)
 
 \d gtest25
-                                 Table "generated_stored_tests.gtest25"
- Column |       Type       | Collation | Nullable |                       Default                        
---------+------------------+-----------+----------+------------------------------------------------------
+                             Table "generated_virtual_tests.gtest25"
+ Column |       Type       | Collation | Nullable |                    Default                    
+--------+------------------+-----------+----------+-----------------------------------------------
  a      | integer          |           | not null | 
- b      | integer          |           |          | generated always as (a * 3) stored
  c      | integer          |           |          | 42
- x      | integer          |           |          | generated always as (c * 4) stored
+ x      | integer          |           |          | generated always as (c * 4)
  d      | double precision |           |          | 101
- y      | double precision |           |          | generated always as (d * 4::double precision) stored
+ y      | double precision |           |          | generated always as (d * 4::double precision)
 Indexes:
     "gtest25_pkey" PRIMARY KEY, btree (a)
 
@@ -1006,7 +937,7 @@ Indexes:
 CREATE TABLE gtest27 (
     a int,
     b int,
-    x int GENERATED ALWAYS AS ((a + b) * 2) STORED
+    x int GENERATED ALWAYS AS ((a + b) * 2) VIRTUAL
 );
 INSERT INTO gtest27 (a, b) VALUES (3, 7), (4, 11);
 ALTER TABLE gtest27 ALTER COLUMN a TYPE text;  -- error
@@ -1014,12 +945,12 @@ ERROR:  cannot alter type of a column used by a generated column
 DETAIL:  Column "a" is used by generated column "x".
 ALTER TABLE gtest27 ALTER COLUMN x TYPE numeric;
 \d gtest27
-                        Table "generated_stored_tests.gtest27"
- Column |  Type   | Collation | Nullable |                  Default                   
---------+---------+-----------+----------+--------------------------------------------
+                    Table "generated_virtual_tests.gtest27"
+ Column |  Type   | Collation | Nullable |               Default               
+--------+---------+-----------+----------+-------------------------------------
  a      | integer |           |          | 
  b      | integer |           |          | 
- x      | numeric |           |          | generated always as (((a + b) * 2)) stored
+ x      | numeric |           |          | generated always as (((a + b) * 2))
 
 SELECT * FROM gtest27;
  a | b  | x  
@@ -1032,20 +963,19 @@ ALTER TABLE gtest27 ALTER COLUMN x TYPE boolean USING x <> 0;  -- error
 ERROR:  generation expression for column "x" cannot be cast automatically to type boolean
 ALTER TABLE gtest27 ALTER COLUMN x DROP DEFAULT;  -- error
 ERROR:  column "x" of relation "gtest27" is a generated column
-HINT:  Use ALTER TABLE ... ALTER COLUMN ... DROP EXPRESSION instead.
 -- It's possible to alter the column types this way:
 ALTER TABLE gtest27
   DROP COLUMN x,
   ALTER COLUMN a TYPE bigint,
   ALTER COLUMN b TYPE bigint,
-  ADD COLUMN x bigint GENERATED ALWAYS AS ((a + b) * 2) STORED;
+  ADD COLUMN x bigint GENERATED ALWAYS AS ((a + b) * 2) VIRTUAL;
 \d gtest27
-                      Table "generated_stored_tests.gtest27"
- Column |  Type  | Collation | Nullable |                 Default                  
---------+--------+-----------+----------+------------------------------------------
+                  Table "generated_virtual_tests.gtest27"
+ Column |  Type  | Collation | Nullable |              Default              
+--------+--------+-----------+----------+-----------------------------------
  a      | bigint |           |          | 
  b      | bigint |           |          | 
- x      | bigint |           |          | generated always as ((a + b) * 2) stored
+ x      | bigint |           |          | generated always as ((a + b) * 2)
 
 -- Ideally you could just do this, but not today (and should x change type?):
 ALTER TABLE gtest27
@@ -1054,12 +984,12 @@ ALTER TABLE gtest27
 ERROR:  cannot alter type of a column used by a generated column
 DETAIL:  Column "a" is used by generated column "x".
 \d gtest27
-                      Table "generated_stored_tests.gtest27"
- Column |  Type  | Collation | Nullable |                 Default                  
---------+--------+-----------+----------+------------------------------------------
+                  Table "generated_virtual_tests.gtest27"
+ Column |  Type  | Collation | Nullable |              Default              
+--------+--------+-----------+----------+-----------------------------------
  a      | bigint |           |          | 
  b      | bigint |           |          | 
- x      | bigint |           |          | generated always as ((a + b) * 2) stored
+ x      | bigint |           |          | generated always as ((a + b) * 2)
 
 SELECT * FROM gtest27;
  a | b  | x  
@@ -1071,7 +1001,7 @@ SELECT * FROM gtest27;
 -- ALTER TABLE ... ALTER COLUMN ... DROP EXPRESSION
 CREATE TABLE gtest29 (
     a int,
-    b int GENERATED ALWAYS AS (a * 2) STORED
+    b int GENERATED ALWAYS AS (a * 2) VIRTUAL
 );
 INSERT INTO gtest29 (a) VALUES (3), (4);
 SELECT * FROM gtest29;
@@ -1082,107 +1012,118 @@ SELECT * FROM gtest29;
 (2 rows)
 
 \d gtest29
-                    Table "generated_stored_tests.gtest29"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
+                Table "generated_virtual_tests.gtest29"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           |          | 
- b      | integer |           |          | generated always as (a * 2) stored
+ b      | integer |           |          | generated always as (a * 2)
 
 ALTER TABLE gtest29 ALTER COLUMN a SET EXPRESSION AS (a * 3);  -- error
 ERROR:  column "a" of relation "gtest29" is not a generated column
 ALTER TABLE gtest29 ALTER COLUMN a DROP EXPRESSION;  -- error
-ERROR:  column "a" of relation "gtest29" is not a stored generated column
+ERROR:  column "a" of relation "gtest29" is not a generated column
 ALTER TABLE gtest29 ALTER COLUMN a DROP EXPRESSION IF EXISTS;  -- notice
-NOTICE:  column "a" of relation "gtest29" is not a stored generated column, skipping
+NOTICE:  column "a" of relation "gtest29" is not a generated column, skipping
 -- Change the expression
 ALTER TABLE gtest29 ALTER COLUMN b SET EXPRESSION AS (a * 3);
+ERROR:  ALTER TABLE / SET EXPRESSION is not supported for virtual generated columns
+DETAIL:  Column "b" of relation "gtest29" is a virtual generated column.
 SELECT * FROM gtest29;
- a | b  
----+----
- 3 |  9
- 4 | 12
+ a | b 
+---+---
+ 3 | 6
+ 4 | 8
 (2 rows)
 
 \d gtest29
-                    Table "generated_stored_tests.gtest29"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
+                Table "generated_virtual_tests.gtest29"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           |          | 
- b      | integer |           |          | generated always as (a * 3) stored
+ b      | integer |           |          | generated always as (a * 2)
 
 ALTER TABLE gtest29 ALTER COLUMN b DROP EXPRESSION;
+ERROR:  ALTER TABLE / DROP EXPRESSION is not supported for virtual generated columns
+DETAIL:  Column "b" of relation "gtest29" is a virtual generated column.
 INSERT INTO gtest29 (a) VALUES (5);
 INSERT INTO gtest29 (a, b) VALUES (6, 66);
+ERROR:  cannot insert a non-DEFAULT value into column "b"
+DETAIL:  Column "b" is a generated column.
 SELECT * FROM gtest29;
  a | b  
 ---+----
- 3 |  9
- 4 | 12
- 5 |   
- 6 | 66
-(4 rows)
+ 3 |  6
+ 4 |  8
+ 5 | 10
+(3 rows)
 
 \d gtest29
-      Table "generated_stored_tests.gtest29"
- Column |  Type   | Collation | Nullable | Default 
---------+---------+-----------+----------+---------
+                Table "generated_virtual_tests.gtest29"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           |          | 
- b      | integer |           |          | 
+ b      | integer |           |          | generated always as (a * 2)
 
 -- check that dependencies between columns have also been removed
 ALTER TABLE gtest29 DROP COLUMN a;  -- should not drop b
+ERROR:  cannot drop column a of table gtest29 because other objects depend on it
+DETAIL:  column b of table gtest29 depends on column a of table gtest29
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.
 \d gtest29
-      Table "generated_stored_tests.gtest29"
- Column |  Type   | Collation | Nullable | Default 
---------+---------+-----------+----------+---------
- b      | integer |           |          | 
+                Table "generated_virtual_tests.gtest29"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
+ a      | integer |           |          | 
+ b      | integer |           |          | generated always as (a * 2)
 
 -- with inheritance
 CREATE TABLE gtest30 (
     a int,
-    b int GENERATED ALWAYS AS (a * 2) STORED
+    b int GENERATED ALWAYS AS (a * 2) VIRTUAL
 );
 CREATE TABLE gtest30_1 () INHERITS (gtest30);
 ALTER TABLE gtest30 ALTER COLUMN b DROP EXPRESSION;
+ERROR:  ALTER TABLE / DROP EXPRESSION is not supported for virtual generated columns
+DETAIL:  Column "b" of relation "gtest30" is a virtual generated column.
 \d gtest30
-      Table "generated_stored_tests.gtest30"
- Column |  Type   | Collation | Nullable | Default 
---------+---------+-----------+----------+---------
+                Table "generated_virtual_tests.gtest30"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           |          | 
- b      | integer |           |          | 
+ b      | integer |           |          | generated always as (a * 2)
 Number of child tables: 1 (Use \d+ to list them.)
 
 \d gtest30_1
-     Table "generated_stored_tests.gtest30_1"
- Column |  Type   | Collation | Nullable | Default 
---------+---------+-----------+----------+---------
+               Table "generated_virtual_tests.gtest30_1"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           |          | 
- b      | integer |           |          | 
+ b      | integer |           |          | generated always as (a * 2)
 Inherits: gtest30
 
 DROP TABLE gtest30 CASCADE;
 NOTICE:  drop cascades to table gtest30_1
 CREATE TABLE gtest30 (
     a int,
-    b int GENERATED ALWAYS AS (a * 2) STORED
+    b int GENERATED ALWAYS AS (a * 2) VIRTUAL
 );
 CREATE TABLE gtest30_1 () INHERITS (gtest30);
 ALTER TABLE ONLY gtest30 ALTER COLUMN b DROP EXPRESSION;  -- error
 ERROR:  ALTER TABLE / DROP EXPRESSION must be applied to child tables too
 \d gtest30
-                    Table "generated_stored_tests.gtest30"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
+                Table "generated_virtual_tests.gtest30"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           |          | 
- b      | integer |           |          | generated always as (a * 2) stored
+ b      | integer |           |          | generated always as (a * 2)
 Number of child tables: 1 (Use \d+ to list them.)
 
 \d gtest30_1
-                   Table "generated_stored_tests.gtest30_1"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
+               Table "generated_virtual_tests.gtest30_1"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  a      | integer |           |          | 
- b      | integer |           |          | generated always as (a * 2) stored
+ b      | integer |           |          | generated always as (a * 2)
 Inherits: gtest30
 
 ALTER TABLE gtest30_1 ALTER COLUMN b DROP EXPRESSION;  -- error
@@ -1190,7 +1131,7 @@ ERROR:  cannot drop generation expression from inherited column
 -- triggers
 CREATE TABLE gtest26 (
     a int PRIMARY KEY,
-    b int GENERATED ALWAYS AS (a * 2) STORED
+    b int GENERATED ALWAYS AS (a * 2) VIRTUAL
 );
 CREATE FUNCTION gtest_trigger_func() RETURNS trigger
   LANGUAGE plpgsql
@@ -1243,7 +1184,7 @@ CREATE TRIGGER gtest4 AFTER INSERT OR UPDATE ON gtest26
   EXECUTE PROCEDURE gtest_trigger_func();
 INSERT INTO gtest26 (a) VALUES (-2), (0), (3);
 INFO:  gtest2: BEFORE: new = (-2,)
-INFO:  gtest4: AFTER: new = (-2,-4)
+INFO:  gtest4: AFTER: new = (-2,)
 SELECT * FROM gtest26 ORDER BY a;
  a  | b  
 ----+----
@@ -1253,12 +1194,12 @@ SELECT * FROM gtest26 ORDER BY a;
 (3 rows)
 
 UPDATE gtest26 SET a = a * -2;
-INFO:  gtest1: BEFORE: old = (-2,-4)
+INFO:  gtest1: BEFORE: old = (-2,)
 INFO:  gtest1: BEFORE: new = (4,)
-INFO:  gtest3: AFTER: old = (-2,-4)
-INFO:  gtest3: AFTER: new = (4,8)
-INFO:  gtest4: AFTER: old = (3,6)
-INFO:  gtest4: AFTER: new = (-6,-12)
+INFO:  gtest3: AFTER: old = (-2,)
+INFO:  gtest3: AFTER: new = (4,)
+INFO:  gtest4: AFTER: old = (3,)
+INFO:  gtest4: AFTER: new = (-6,)
 SELECT * FROM gtest26 ORDER BY a;
  a  |  b  
 ----+-----
@@ -1268,8 +1209,8 @@ SELECT * FROM gtest26 ORDER BY a;
 (3 rows)
 
 DELETE FROM gtest26 WHERE a = -6;
-INFO:  gtest1: BEFORE: old = (-6,-12)
-INFO:  gtest3: AFTER: old = (-6,-12)
+INFO:  gtest1: BEFORE: old = (-6,)
+INFO:  gtest3: AFTER: old = (-6,)
 SELECT * FROM gtest26 ORDER BY a;
  a | b 
 ---+---
@@ -1280,6 +1221,8 @@ SELECT * FROM gtest26 ORDER BY a;
 DROP TRIGGER gtest1 ON gtest26;
 DROP TRIGGER gtest2 ON gtest26;
 DROP TRIGGER gtest3 ON gtest26;
+-- check disallowed modification of virtual columns
+-- TODO
 -- Check that an UPDATE of "a" fires the trigger for UPDATE OF b, per
 -- SQL standard.
 CREATE FUNCTION gtest_trigger_func3() RETURNS trigger
@@ -1293,9 +1236,11 @@ $$;
 CREATE TRIGGER gtest11 BEFORE UPDATE OF b ON gtest26
   FOR EACH ROW
   EXECUTE PROCEDURE gtest_trigger_func3();
+ERROR:  virtual generated columns are not supported as trigger columns
+DETAIL:  Column "b" is a virtual generated column.
 UPDATE gtest26 SET a = 1 WHERE a = 0;
-NOTICE:  OK
 DROP TRIGGER gtest11 ON gtest26;
+ERROR:  trigger "gtest11" for table "gtest26" does not exist
 TRUNCATE gtest26;
 -- check that modifications of stored generated columns in triggers do
 -- not get propagated
@@ -1319,14 +1264,13 @@ CREATE TRIGGER gtest12_03 BEFORE UPDATE ON gtest26
   EXECUTE PROCEDURE gtest_trigger_func();
 INSERT INTO gtest26 (a) VALUES (1);
 UPDATE gtest26 SET a = 11 WHERE a = 1;
-INFO:  gtest12_01: BEFORE: old = (1,2)
+INFO:  gtest12_01: BEFORE: old = (1,)
 INFO:  gtest12_01: BEFORE: new = (11,)
-INFO:  gtest12_03: BEFORE: old = (1,2)
-INFO:  gtest12_03: BEFORE: new = (10,)
+ERROR:  trigger modified virtual generated column value
 SELECT * FROM gtest26 ORDER BY a;
- a  | b  
-----+----
- 10 | 20
+ a | b 
+---+---
+ 1 | 2
 (1 row)
 
 -- LIKE INCLUDING GENERATED and dropped column handling
@@ -1334,22 +1278,22 @@ CREATE TABLE gtest28a (
   a int,
   b int,
   c int,
-  x int GENERATED ALWAYS AS (b * 2) STORED
+  x int GENERATED ALWAYS AS (b * 2) VIRTUAL
 );
 ALTER TABLE gtest28a DROP COLUMN a;
 CREATE TABLE gtest28b (LIKE gtest28a INCLUDING GENERATED);
 \d gtest28*
-                   Table "generated_stored_tests.gtest28a"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
+               Table "generated_virtual_tests.gtest28a"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  b      | integer |           |          | 
  c      | integer |           |          | 
- x      | integer |           |          | generated always as (b * 2) stored
+ x      | integer |           |          | generated always as (b * 2)
 
-                   Table "generated_stored_tests.gtest28b"
- Column |  Type   | Collation | Nullable |              Default               
---------+---------+-----------+----------+------------------------------------
+               Table "generated_virtual_tests.gtest28b"
+ Column |  Type   | Collation | Nullable |           Default           
+--------+---------+-----------+----------+-----------------------------
  b      | integer |           |          | 
  c      | integer |           |          | 
- x      | integer |           |          | generated always as (b * 2) stored
+ x      | integer |           |          | generated always as (b * 2)
 
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index d4bbc0db25b..fbce82cf7e4 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -68,6 +68,9 @@ test: select_into select_distinct select_distinct_on select_implicit select_havi
 # ----------
 test: brin gin gist spgist privileges init_privs security_label collate matview lock replica_identity rowsecurity object_address tablesample groupingsets drop_operator password identity generated_stored join_hash
 
+# TODO: find a place for this (above group is full)
+test: generated_virtual
+
 # ----------
 # Additional BRIN tests
 # ----------
diff --git a/src/test/regress/sql/create_table_like.sql b/src/test/regress/sql/create_table_like.sql
index 4929d373a2f..3ae42a99272 100644
--- a/src/test/regress/sql/create_table_like.sql
+++ b/src/test/regress/sql/create_table_like.sql
@@ -51,7 +51,7 @@ CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
 SELECT * FROM test_like_id_3;  -- identity was copied and applied
 DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
 
-CREATE TABLE test_like_gen_1 (a int, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE test_like_gen_1 (a int, b int GENERATED ALWAYS AS (a * 2) STORED, c int GENERATED ALWAYS AS (a * 3) VIRTUAL);
 \d test_like_gen_1
 INSERT INTO test_like_gen_1 (a) VALUES (1);
 SELECT * FROM test_like_gen_1;
diff --git a/src/test/regress/sql/generated_stored.sql b/src/test/regress/sql/generated_stored.sql
index c18e0e1f655..03ea1954903 100644
--- a/src/test/regress/sql/generated_stored.sql
+++ b/src/test/regress/sql/generated_stored.sql
@@ -1,5 +1,5 @@
 -- sanity check of system catalog
-SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT IN ('', 's');
+SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT IN ('', 's', 'v');

 CREATE SCHEMA generated_stored_tests;
diff --git a/src/test/regress/sql/generated_stored.sql b/src/test/regress/sql/generated_virtual.sql
similarity index 74%
copy from src/test/regress/sql/generated_stored.sql
copy to src/test/regress/sql/generated_virtual.sql
index c18e0e1f655..b1c4421c3ed 100644
--- a/src/test/regress/sql/generated_stored.sql
+++ b/src/test/regress/sql/generated_virtual.sql
@@ -1,55 +1,55 @@
 -- sanity check of system catalog
-SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT IN ('', 's');
+SELECT attrelid, attname, attgenerated FROM pg_attribute WHERE attgenerated NOT IN ('', 's', 'v');

-CREATE SCHEMA generated_stored_tests;
-GRANT USAGE ON SCHEMA generated_stored_tests TO PUBLIC;
-SET search_path = generated_stored_tests;
+CREATE SCHEMA generated_virtual_tests;
+GRANT USAGE ON SCHEMA generated_virtual_tests TO PUBLIC;
+SET search_path = generated_virtual_tests;
 
-CREATE TABLE gtest0 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (55) STORED);
-CREATE TABLE gtest1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest0 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (55) VIRTUAL);
+CREATE TABLE gtest1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 
-SELECT table_name, column_name, column_default, is_nullable, is_generated, generation_expression FROM information_schema.columns WHERE table_schema = 'generated_stored_tests' ORDER BY 1, 2;
+SELECT table_name, column_name, column_default, is_nullable, is_generated, generation_expression FROM information_schema.columns WHERE table_schema = 'generated_virtual_tests' ORDER BY 1, 2;
 
-SELECT table_name, column_name, dependent_column FROM information_schema.column_column_usage WHERE table_schema = 'generated_stored_tests' ORDER BY 1, 2, 3;
+SELECT table_name, column_name, dependent_column FROM information_schema.column_column_usage WHERE table_schema = 'generated_virtual_tests' ORDER BY 1, 2, 3;
 
 \d gtest1
 
 -- duplicate generated
-CREATE TABLE gtest_err_1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED GENERATED ALWAYS AS (a * 3) STORED);
+CREATE TABLE gtest_err_1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL GENERATED ALWAYS AS (a * 3) VIRTUAL);
 
 -- references to other generated columns, including self-references
-CREATE TABLE gtest_err_2a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (b * 2) STORED);
-CREATE TABLE gtest_err_2b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED, c int GENERATED ALWAYS AS (b * 3) STORED);
+CREATE TABLE gtest_err_2a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (b * 2) VIRTUAL);
+CREATE TABLE gtest_err_2b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL, c int GENERATED ALWAYS AS (b * 3) VIRTUAL);
 -- a whole-row var is a self-reference on steroids, so disallow that too
 CREATE TABLE gtest_err_2c (a int PRIMARY KEY,
-    b int GENERATED ALWAYS AS (num_nulls(gtest_err_2c)) STORED);
+    b int GENERATED ALWAYS AS (num_nulls(gtest_err_2c)) VIRTUAL);
 
 -- invalid reference
-CREATE TABLE gtest_err_3 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (c * 2) STORED);
+CREATE TABLE gtest_err_3 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (c * 2) VIRTUAL);
 
 -- generation expression must be immutable
-CREATE TABLE gtest_err_4 (a int PRIMARY KEY, b double precision GENERATED ALWAYS AS (random()) STORED);
+CREATE TABLE gtest_err_4 (a int PRIMARY KEY, b double precision GENERATED ALWAYS AS (random()) VIRTUAL);
 -- ... but be sure that the immutability test is accurate
-CREATE TABLE gtest2 (a int, b text GENERATED ALWAYS AS (a || ' sec') STORED);
+CREATE TABLE gtest2 (a int, b text GENERATED ALWAYS AS (a || ' sec') VIRTUAL);
 DROP TABLE gtest2;
 
 -- cannot have default/identity and generated
-CREATE TABLE gtest_err_5a (a int PRIMARY KEY, b int DEFAULT 5 GENERATED ALWAYS AS (a * 2) STORED);
-CREATE TABLE gtest_err_5b (a int PRIMARY KEY, b int GENERATED ALWAYS AS identity GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest_err_5a (a int PRIMARY KEY, b int DEFAULT 5 GENERATED ALWAYS AS (a * 2) VIRTUAL);
+CREATE TABLE gtest_err_5b (a int PRIMARY KEY, b int GENERATED ALWAYS AS identity GENERATED ALWAYS AS (a * 2) VIRTUAL);
 
 -- reference to system column not allowed in generated column
 -- (except tableoid, which we test below)
-CREATE TABLE gtest_err_6a (a int PRIMARY KEY, b bool GENERATED ALWAYS AS (xmin <> 37) STORED);
+CREATE TABLE gtest_err_6a (a int PRIMARY KEY, b bool GENERATED ALWAYS AS (xmin <> 37) VIRTUAL);
 
 -- various prohibited constructs
-CREATE TABLE gtest_err_7a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (avg(a)) STORED);
-CREATE TABLE gtest_err_7b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (row_number() OVER (ORDER BY a)) STORED);
-CREATE TABLE gtest_err_7c (a int PRIMARY KEY, b int GENERATED ALWAYS AS ((SELECT a)) STORED);
-CREATE TABLE gtest_err_7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generate_series(1, a)) STORED);
+CREATE TABLE gtest_err_7a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (avg(a)) VIRTUAL);
+CREATE TABLE gtest_err_7b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (row_number() OVER (ORDER BY a)) VIRTUAL);
+CREATE TABLE gtest_err_7c (a int PRIMARY KEY, b int GENERATED ALWAYS AS ((SELECT a)) VIRTUAL);
+CREATE TABLE gtest_err_7d (a int PRIMARY KEY, b int GENERATED ALWAYS AS (generate_series(1, a)) VIRTUAL);
 
 -- GENERATED BY DEFAULT not allowed
-CREATE TABLE gtest_err_8 (a int PRIMARY KEY, b int GENERATED BY DEFAULT AS (a * 2) STORED);
+CREATE TABLE gtest_err_8 (a int PRIMARY KEY, b int GENERATED BY DEFAULT AS (a * 2) VIRTUAL);
 
 INSERT INTO gtest1 VALUES (1);
 INSERT INTO gtest1 VALUES (2, DEFAULT);  -- ok
@@ -70,7 +70,7 @@ CREATE TABLE gtest_err_8 (a int PRIMARY KEY, b int GENERATED BY DEFAULT AS (a *
 SELECT a, b, b * 2 AS b2 FROM gtest1 ORDER BY a;
 SELECT a, b FROM gtest1 WHERE b = 4 ORDER BY a;
 
--- test that overflow error happens on write
+-- test that overflow error happens on read
 INSERT INTO gtest1 VALUES (2000000000);
 SELECT * FROM gtest1;
 DELETE FROM gtest1 WHERE a = 2000000000;
@@ -93,8 +93,8 @@ CREATE TABLE gtestm (
   id int PRIMARY KEY,
   f1 int,
   f2 int,
-  f3 int GENERATED ALWAYS AS (f1 * 2) STORED,
-  f4 int GENERATED ALWAYS AS (f2 * 2) STORED
+  f3 int GENERATED ALWAYS AS (f1 * 2) VIRTUAL,
+  f4 int GENERATED ALWAYS AS (f2 * 2) VIRTUAL
 );
 INSERT INTO gtestm VALUES (1, 5, 100);
 MERGE INTO gtestm t USING (VALUES (1, 10), (2, 20)) v(id, f1) ON t.id = v.id
@@ -134,22 +134,26 @@ CREATE TABLE gtest1_1 () INHERITS (gtest1);
 
 -- can't have generated column that is a child of normal column
 CREATE TABLE gtest_normal (a int, b int);
-CREATE TABLE gtest_normal_child (a int, b int GENERATED ALWAYS AS (a * 2) STORED) INHERITS (gtest_normal);  -- error
-CREATE TABLE gtest_normal_child (a int, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest_normal_child (a int, b int GENERATED ALWAYS AS (a * 2) VIRTUAL) INHERITS (gtest_normal);  -- error
+CREATE TABLE gtest_normal_child (a int, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 ALTER TABLE gtest_normal_child INHERIT gtest_normal;  -- error
 DROP TABLE gtest_normal, gtest_normal_child;
 
 -- test inheritance mismatches between parent and child
 CREATE TABLE gtestx (x int, b int DEFAULT 10) INHERITS (gtest1);  -- error
 CREATE TABLE gtestx (x int, b int GENERATED ALWAYS AS IDENTITY) INHERITS (gtest1);  -- error
-CREATE TABLE gtestx (x int, b int GENERATED ALWAYS AS (a * 22) STORED) INHERITS (gtest1);  -- ok, overrides parent
+CREATE TABLE gtestx (x int, b int GENERATED ALWAYS AS (a * 22) STORED) INHERITS (gtest1);  -- error
+CREATE TABLE gtestx (x int, b int GENERATED ALWAYS AS (a * 22) VIRTUAL) INHERITS (gtest1);  -- ok, overrides parent
 \d+ gtestx
+INSERT INTO gtestx (a, x) VALUES (11, 22);
+SELECT * FROM gtest1;
+SELECT * FROM gtestx;
 
 CREATE TABLE gtestxx_1 (a int NOT NULL, b int);
 ALTER TABLE gtestxx_1 INHERIT gtest1;  -- error
-CREATE TABLE gtestxx_3 (a int NOT NULL, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtestxx_3 (a int NOT NULL, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 ALTER TABLE gtestxx_3 INHERIT gtest1;  -- ok
-CREATE TABLE gtestxx_4 (b int GENERATED ALWAYS AS (a * 2) STORED, a int NOT NULL);
+CREATE TABLE gtestxx_4 (b int GENERATED ALWAYS AS (a * 2) VIRTUAL, a int NOT NULL);
 ALTER TABLE gtestxx_4 INHERIT gtest1;  -- ok
 
 -- test multiple inheritance mismatches
@@ -161,28 +165,28 @@ CREATE TABLE gtesty (x int, b int);
 CREATE TABLE gtest1_y () INHERITS (gtest1, gtesty);  -- error
 DROP TABLE gtesty;
 
-CREATE TABLE gtesty (x int, b int GENERATED ALWAYS AS (x * 22) STORED);
+CREATE TABLE gtesty (x int, b int GENERATED ALWAYS AS (x * 22) VIRTUAL);
 CREATE TABLE gtest1_y () INHERITS (gtest1, gtesty);  -- error
-CREATE TABLE gtest1_y (b int GENERATED ALWAYS AS (x + 1) STORED) INHERITS (gtest1, gtesty);  -- ok
+CREATE TABLE gtest1_y (b int GENERATED ALWAYS AS (x + 1) VIRTUAL) INHERITS (gtest1, gtesty);  -- ok
 \d gtest1_y
 
 -- test correct handling of GENERATED column that's only in child
 CREATE TABLE gtestp (f1 int);
-CREATE TABLE gtestc (f2 int GENERATED ALWAYS AS (f1+1) STORED) INHERITS(gtestp);
+CREATE TABLE gtestc (f2 int GENERATED ALWAYS AS (f1+1) VIRTUAL) INHERITS(gtestp);
 INSERT INTO gtestc values(42);
 TABLE gtestc;
 UPDATE gtestp SET f1 = f1 * 10;
 TABLE gtestc;
 DROP TABLE gtestp CASCADE;
 
--- test stored update
-CREATE TABLE gtest3 (a int, b int GENERATED ALWAYS AS (a * 3) STORED);
+-- test update XXX
+CREATE TABLE gtest3 (a int, b int GENERATED ALWAYS AS (a * 3) VIRTUAL);
 INSERT INTO gtest3 (a) VALUES (1), (2), (3), (NULL);
 SELECT * FROM gtest3 ORDER BY a;
 UPDATE gtest3 SET a = 22 WHERE a = 2;
 SELECT * FROM gtest3 ORDER BY a;
 
-CREATE TABLE gtest3a (a text, b text GENERATED ALWAYS AS (a || '+' || a) STORED);
+CREATE TABLE gtest3a (a text, b text GENERATED ALWAYS AS (a || '+' || a) VIRTUAL);
 INSERT INTO gtest3a (a) VALUES ('a'), ('b'), ('c'), (NULL);
 SELECT * FROM gtest3a ORDER BY a;
 UPDATE gtest3a SET a = 'bb' WHERE a = 'b';
@@ -222,12 +226,12 @@ CREATE TABLE gtest3a (a text, b text GENERATED ALWAYS AS (a || '+' || a) STORED)
 SELECT * FROM gtest3 ORDER BY a;
 
 -- null values
-CREATE TABLE gtest2 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (NULL) STORED);
+CREATE TABLE gtest2 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (NULL) VIRTUAL);
 INSERT INTO gtest2 VALUES (1);
 SELECT * FROM gtest2;
 
 -- simple column reference for varlena types
-CREATE TABLE gtest_varlena (a varchar, b varchar GENERATED ALWAYS AS (a) STORED);
+CREATE TABLE gtest_varlena (a varchar, b varchar GENERATED ALWAYS AS (a) VIRTUAL);
 INSERT INTO gtest_varlena (a) VALUES('01234567890123456789');
 INSERT INTO gtest_varlena (a) VALUES(NULL);
 SELECT * FROM gtest_varlena ORDER BY a;
@@ -237,7 +241,7 @@ CREATE TABLE gtest_varlena (a varchar, b varchar GENERATED ALWAYS AS (a) STORED)
 CREATE TYPE double_int as (a int, b int);
 CREATE TABLE gtest4 (
     a int,
-    b double_int GENERATED ALWAYS AS ((a * 2, a * 3)) STORED
+    b double_int GENERATED ALWAYS AS ((a * 2, a * 3)) VIRTUAL
 );
 INSERT INTO gtest4 VALUES (1), (6);
 SELECT * FROM gtest4;
@@ -248,168 +252,168 @@ CREATE TABLE gtest4 (
 -- using tableoid is allowed
 CREATE TABLE gtest_tableoid (
   a int PRIMARY KEY,
-  b bool GENERATED ALWAYS AS (tableoid = 'gtest_tableoid'::regclass) STORED
+  b bool GENERATED ALWAYS AS (tableoid = 'gtest_tableoid'::regclass) VIRTUAL
 );
 INSERT INTO gtest_tableoid VALUES (1), (2);
 ALTER TABLE gtest_tableoid ADD COLUMN
-  c regclass GENERATED ALWAYS AS (tableoid) STORED;
+  c regclass GENERATED ALWAYS AS (tableoid) VIRTUAL;
 SELECT * FROM gtest_tableoid;
 
 -- drop column behavior
-CREATE TABLE gtest10 (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (b * 2) STORED);
+CREATE TABLE gtest10 (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (b * 2) VIRTUAL);
 ALTER TABLE gtest10 DROP COLUMN b;  -- fails
 ALTER TABLE gtest10 DROP COLUMN b CASCADE;  -- drops c too
 
 \d gtest10
 
-CREATE TABLE gtest10a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest10a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 ALTER TABLE gtest10a DROP COLUMN b;
 INSERT INTO gtest10a (a) VALUES (1);
 
 -- privileges
 CREATE USER regress_user11;
 
-CREATE TABLE gtest11s (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (b * 2) STORED);
-INSERT INTO gtest11s VALUES (1, 10), (2, 20);
-GRANT SELECT (a, c) ON gtest11s TO regress_user11;
+CREATE TABLE gtest11v (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (b * 2) VIRTUAL);
+INSERT INTO gtest11v VALUES (1, 10), (2, 20);
+GRANT SELECT (a, c) ON gtest11v TO regress_user11;
 
 CREATE FUNCTION gf1(a int) RETURNS int AS $$ SELECT a * 3 $$ IMMUTABLE LANGUAGE SQL;
 REVOKE ALL ON FUNCTION gf1(int) FROM PUBLIC;
 
-CREATE TABLE gtest12s (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (gf1(b)) STORED);
-INSERT INTO gtest12s VALUES (1, 10), (2, 20);
+CREATE TABLE gtest12v (a int PRIMARY KEY, b int, c int GENERATED ALWAYS AS (gf1(b)) VIRTUAL);
+INSERT INTO gtest12v VALUES (1, 10), (2, 20);
 GRANT SELECT (a, c) ON gtest12s TO regress_user11;
 
 SET ROLE regress_user11;
-SELECT a, b FROM gtest11s;  -- not allowed
-SELECT a, c FROM gtest11s;  -- allowed
+SELECT a, b FROM gtest11v;  -- not allowed
+SELECT a, c FROM gtest11v;  -- allowed
 SELECT gf1(10);  -- not allowed
-SELECT a, c FROM gtest12s;  -- allowed
+SELECT a, c FROM gtest12v;  -- not allowed; TODO: ought to be allowed
 RESET ROLE;
 
 DROP FUNCTION gf1(int);  -- fail
-DROP TABLE gtest11s, gtest12s;
+DROP TABLE gtest11v, gtest12v;
 DROP FUNCTION gf1(int);
 DROP USER regress_user11;
 
 -- check constraints
-CREATE TABLE gtest20 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED CHECK (b < 50));
+CREATE TABLE gtest20 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL CHECK (b < 50));
 INSERT INTO gtest20 (a) VALUES (10);  -- ok
 INSERT INTO gtest20 (a) VALUES (30);  -- violates constraint
 
 ALTER TABLE gtest20 ALTER COLUMN b SET EXPRESSION AS (a * 100);  -- violates constraint
 ALTER TABLE gtest20 ALTER COLUMN b SET EXPRESSION AS (a * 3);  -- ok
 
-CREATE TABLE gtest20a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest20a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 INSERT INTO gtest20a (a) VALUES (10);
 INSERT INTO gtest20a (a) VALUES (30);
 ALTER TABLE gtest20a ADD CHECK (b < 50);  -- fails on existing row
 
-CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED);
+CREATE TABLE gtest20b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
 INSERT INTO gtest20b (a) VALUES (10);
 INSERT INTO gtest20b (a) VALUES (30);
 ALTER TABLE gtest20b ADD CONSTRAINT chk CHECK (b < 50) NOT VALID;
 ALTER TABLE gtest20b VALIDATE CONSTRAINT chk;  -- fails on existing row
 
--- not-null constraints
-CREATE TABLE gtest21a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (nullif(a, 0)) STORED NOT NULL);
-INSERT INTO gtest21a (a) VALUES (1);  -- ok
-INSERT INTO gtest21a (a) VALUES (0);  -- violates constraint
+-- not-null constraints (currently not supported)
+CREATE TABLE gtest21a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (nullif(a, 0)) VIRTUAL NOT NULL);
+--INSERT INTO gtest21a (a) VALUES (1);  -- ok
+--INSERT INTO gtest21a (a) VALUES (0);  -- violates constraint
 
-CREATE TABLE gtest21b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (nullif(a, 0)) STORED);
+CREATE TABLE gtest21b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (nullif(a, 0)) VIRTUAL);
 ALTER TABLE gtest21b ALTER COLUMN b SET NOT NULL;
-INSERT INTO gtest21b (a) VALUES (1);  -- ok
-INSERT INTO gtest21b (a) VALUES (0);  -- violates constraint
+--INSERT INTO gtest21b (a) VALUES (1);  -- ok
+--INSERT INTO gtest21b (a) VALUES (0);  -- violates constraint
 ALTER TABLE gtest21b ALTER COLUMN b DROP NOT NULL;
-INSERT INTO gtest21b (a) VALUES (0);  -- ok now
+--INSERT INTO gtest21b (a) VALUES (0);  -- ok now
 
 -- index constraints
-CREATE TABLE gtest22a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a / 2) STORED UNIQUE);
-INSERT INTO gtest22a VALUES (2);
-INSERT INTO gtest22a VALUES (3);
-INSERT INTO gtest22a VALUES (4);
-CREATE TABLE gtest22b (a int, b int GENERATED ALWAYS AS (a / 2) STORED, PRIMARY KEY (a, b));
-INSERT INTO gtest22b VALUES (2);
-INSERT INTO gtest22b VALUES (2);
+CREATE TABLE gtest22a (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a / 2) VIRTUAL UNIQUE);
+--INSERT INTO gtest22a VALUES (2);
+--INSERT INTO gtest22a VALUES (3);
+--INSERT INTO gtest22a VALUES (4);
+CREATE TABLE gtest22b (a int, b int GENERATED ALWAYS AS (a / 2) VIRTUAL, PRIMARY KEY (a, b));
+--INSERT INTO gtest22b VALUES (2);
+--INSERT INTO gtest22b VALUES (2);
 
 -- indexes
-CREATE TABLE gtest22c (a int, b int GENERATED ALWAYS AS (a * 2) STORED);
-CREATE INDEX gtest22c_b_idx ON gtest22c (b);
-CREATE INDEX gtest22c_expr_idx ON gtest22c ((b * 3));
-CREATE INDEX gtest22c_pred_idx ON gtest22c (a) WHERE b > 0;
-\d gtest22c
-
-INSERT INTO gtest22c VALUES (1), (2), (3);
-SET enable_seqscan TO off;
-SET enable_bitmapscan TO off;
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b = 4;
-SELECT * FROM gtest22c WHERE b = 4;
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b * 3 = 6;
-SELECT * FROM gtest22c WHERE b * 3 = 6;
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
-SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
-
-ALTER TABLE gtest22c ALTER COLUMN b SET EXPRESSION AS (a * 4);
-ANALYZE gtest22c;
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b = 8;
-SELECT * FROM gtest22c WHERE b = 8;
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b * 3 = 12;
-SELECT * FROM gtest22c WHERE b * 3 = 12;
-EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
-SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
-RESET enable_seqscan;
-RESET enable_bitmapscan;
+CREATE TABLE gtest22c (a int, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
+--CREATE INDEX gtest22c_b_idx ON gtest22c (b);
+--CREATE INDEX gtest22c_expr_idx ON gtest22c ((b * 3));
+--CREATE INDEX gtest22c_pred_idx ON gtest22c (a) WHERE b > 0;
+--\d gtest22c
+
+--INSERT INTO gtest22c VALUES (1), (2), (3);
+--SET enable_seqscan TO off;
+--SET enable_bitmapscan TO off;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b = 4;
+--SELECT * FROM gtest22c WHERE b = 4;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b * 3 = 6;
+--SELECT * FROM gtest22c WHERE b * 3 = 6;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
+--SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
+
+--ALTER TABLE gtest22c ALTER COLUMN b SET EXPRESSION AS (a * 4);
+--ANALYZE gtest22c;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b = 8;
+--SELECT * FROM gtest22c WHERE b = 8;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE b * 3 = 12;
+--SELECT * FROM gtest22c WHERE b * 3 = 12;
+--EXPLAIN (COSTS OFF) SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
+--SELECT * FROM gtest22c WHERE a = 1 AND b > 0;
+--RESET enable_seqscan;
+--RESET enable_bitmapscan;
 
 -- foreign keys
 CREATE TABLE gtest23a (x int PRIMARY KEY, y int);
-INSERT INTO gtest23a VALUES (1, 11), (2, 22), (3, 33);
+--INSERT INTO gtest23a VALUES (1, 11), (2, 22), (3, 33);
 
-CREATE TABLE gtest23x (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED REFERENCES gtest23a (x) ON UPDATE CASCADE);  -- error
-CREATE TABLE gtest23x (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED REFERENCES gtest23a (x) ON DELETE SET NULL);  -- error
+CREATE TABLE gtest23x (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL REFERENCES gtest23a (x) ON UPDATE CASCADE);  -- error
+CREATE TABLE gtest23x (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL REFERENCES gtest23a (x) ON DELETE SET NULL);  -- error
 
-CREATE TABLE gtest23b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED REFERENCES gtest23a (x));
-\d gtest23b
+CREATE TABLE gtest23b (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL REFERENCES gtest23a (x));
+--\d gtest23b
 
-INSERT INTO gtest23b VALUES (1);  -- ok
-INSERT INTO gtest23b VALUES (5);  -- error
-ALTER TABLE gtest23b ALTER COLUMN b SET EXPRESSION AS (a * 5); -- error
-ALTER TABLE gtest23b ALTER COLUMN b SET EXPRESSION AS (a * 1); -- ok
+--INSERT INTO gtest23b VALUES (1);  -- ok
+--INSERT INTO gtest23b VALUES (5);  -- error
+--ALTER TABLE gtest23b ALTER COLUMN b SET EXPRESSION AS (a * 5); -- error
+--ALTER TABLE gtest23b ALTER COLUMN b SET EXPRESSION AS (a * 1); -- ok
 
-DROP TABLE gtest23b;
-DROP TABLE gtest23a;
+--DROP TABLE gtest23b;
+--DROP TABLE gtest23a;
 
-CREATE TABLE gtest23p (x int, y int GENERATED ALWAYS AS (x * 2) STORED, PRIMARY KEY (y));
-INSERT INTO gtest23p VALUES (1), (2), (3);
+CREATE TABLE gtest23p (x int, y int GENERATED ALWAYS AS (x * 2) VIRTUAL, PRIMARY KEY (y));
+--INSERT INTO gtest23p VALUES (1), (2), (3);
 
 CREATE TABLE gtest23q (a int PRIMARY KEY, b int REFERENCES gtest23p (y));
-INSERT INTO gtest23q VALUES (1, 2);  -- ok
-INSERT INTO gtest23q VALUES (2, 5);  -- error
+--INSERT INTO gtest23q VALUES (1, 2);  -- ok
+--INSERT INTO gtest23q VALUES (2, 5);  -- error
 
 -- domains
 CREATE DOMAIN gtestdomain1 AS int CHECK (VALUE < 10);
-CREATE TABLE gtest24 (a int PRIMARY KEY, b gtestdomain1 GENERATED ALWAYS AS (a * 2) STORED);
-INSERT INTO gtest24 (a) VALUES (4);  -- ok
-INSERT INTO gtest24 (a) VALUES (6);  -- error
+CREATE TABLE gtest24 (a int PRIMARY KEY, b gtestdomain1 GENERATED ALWAYS AS (a * 2) VIRTUAL);
+--INSERT INTO gtest24 (a) VALUES (4);  -- ok
+--INSERT INTO gtest24 (a) VALUES (6);  -- error
 
 -- typed tables (currently not supported)
 CREATE TYPE gtest_type AS (f1 integer, f2 text, f3 bigint);
-CREATE TABLE gtest28 OF gtest_type (f1 WITH OPTIONS GENERATED ALWAYS AS (f2 *2) STORED);
+CREATE TABLE gtest28 OF gtest_type (f1 WITH OPTIONS GENERATED ALWAYS AS (f2 *2) VIRTUAL);
 DROP TYPE gtest_type CASCADE;
 
 -- partitioning cases
 CREATE TABLE gtest_parent (f1 date NOT NULL, f2 bigint, f3 bigint) PARTITION BY RANGE (f1);
 CREATE TABLE gtest_child PARTITION OF gtest_parent (
-    f3 WITH OPTIONS GENERATED ALWAYS AS (f2 * 2) STORED
+    f3 WITH OPTIONS GENERATED ALWAYS AS (f2 * 2) VIRTUAL
 ) FOR VALUES FROM ('2016-07-01') TO ('2016-08-01'); -- error
-CREATE TABLE gtest_child (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) STORED);
+CREATE TABLE gtest_child (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) VIRTUAL);
 ALTER TABLE gtest_parent ATTACH PARTITION gtest_child FOR VALUES FROM ('2016-07-01') TO ('2016-08-01'); -- error
 DROP TABLE gtest_parent, gtest_child;
 
-CREATE TABLE gtest_parent (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) STORED) PARTITION BY RANGE (f1);
+CREATE TABLE gtest_parent (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) VIRTUAL) PARTITION BY RANGE (f1);
 CREATE TABLE gtest_child PARTITION OF gtest_parent
   FOR VALUES FROM ('2016-07-01') TO ('2016-08-01');  -- inherits gen expr
 CREATE TABLE gtest_child2 PARTITION OF gtest_parent (
-    f3 WITH OPTIONS GENERATED ALWAYS AS (f2 * 22) STORED  -- overrides gen expr
+    f3 WITH OPTIONS GENERATED ALWAYS AS (f2 * 22) VIRTUAL  -- overrides gen expr
 ) FOR VALUES FROM ('2016-08-01') TO ('2016-09-01');
 CREATE TABLE gtest_child3 PARTITION OF gtest_parent (
     f3 DEFAULT 42  -- error
@@ -417,6 +421,9 @@ CREATE TABLE gtest_child3 PARTITION OF gtest_parent (
 CREATE TABLE gtest_child3 PARTITION OF gtest_parent (
     f3 WITH OPTIONS GENERATED ALWAYS AS IDENTITY  -- error
 ) FOR VALUES FROM ('2016-09-01') TO ('2016-10-01');
+CREATE TABLE gtest_child3 PARTITION OF gtest_parent (
+    f3 GENERATED ALWAYS AS (f2 * 2) STORED  -- error
+) FOR VALUES FROM ('2016-09-01') TO ('2016-10-01');
 CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint);
 ALTER TABLE gtest_parent ATTACH PARTITION gtest_child3 FOR VALUES FROM ('2016-09-01') TO ('2016-10-01'); -- error
 DROP TABLE gtest_child3;
@@ -426,7 +433,7 @@ CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint DEFAULT 42);
 CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS IDENTITY);
 ALTER TABLE gtest_parent ATTACH PARTITION gtest_child3 FOR VALUES FROM ('2016-09-01') TO ('2016-10-01'); -- error
 DROP TABLE gtest_child3;
-CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 33) STORED);
+CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 33) VIRTUAL);
 ALTER TABLE gtest_parent ATTACH PARTITION gtest_child3 FOR VALUES FROM ('2016-09-01') TO ('2016-10-01');
 \d gtest_child
 \d gtest_child2
@@ -457,21 +464,21 @@ CREATE TABLE gtest_child3 (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWA
 -- we leave these tables around for purposes of testing dump/reload/upgrade
 
 -- generated columns in partition key (not allowed)
-CREATE TABLE gtest_part_key (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) STORED) PARTITION BY RANGE (f3);
-CREATE TABLE gtest_part_key (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) STORED) PARTITION BY RANGE ((f3 * 3));
+CREATE TABLE gtest_part_key (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) VIRTUAL) PARTITION BY RANGE (f3);
+CREATE TABLE gtest_part_key (f1 date NOT NULL, f2 bigint, f3 bigint GENERATED ALWAYS AS (f2 * 2) VIRTUAL) PARTITION BY RANGE ((f3 * 3));
 
 -- ALTER TABLE ... ADD COLUMN
 CREATE TABLE gtest25 (a int PRIMARY KEY);
 INSERT INTO gtest25 VALUES (3), (4);
-ALTER TABLE gtest25 ADD COLUMN b int GENERATED ALWAYS AS (a * 2) STORED, ALTER COLUMN b SET EXPRESSION AS (a * 3);
+ALTER TABLE gtest25 ADD COLUMN b int GENERATED ALWAYS AS (a * 2) VIRTUAL, ALTER COLUMN b SET EXPRESSION AS (a * 3);
 SELECT * FROM gtest25 ORDER BY a;
-ALTER TABLE gtest25 ADD COLUMN x int GENERATED ALWAYS AS (b * 4) STORED;  -- error
-ALTER TABLE gtest25 ADD COLUMN x int GENERATED ALWAYS AS (z * 4) STORED;  -- error
+ALTER TABLE gtest25 ADD COLUMN x int GENERATED ALWAYS AS (b * 4) VIRTUAL;  -- error
+ALTER TABLE gtest25 ADD COLUMN x int GENERATED ALWAYS AS (z * 4) VIRTUAL;  -- error
 ALTER TABLE gtest25 ADD COLUMN c int DEFAULT 42,
-  ADD COLUMN x int GENERATED ALWAYS AS (c * 4) STORED;
+  ADD COLUMN x int GENERATED ALWAYS AS (c * 4) VIRTUAL;
 ALTER TABLE gtest25 ADD COLUMN d int DEFAULT 101;
 ALTER TABLE gtest25 ALTER COLUMN d SET DATA TYPE float8,
-  ADD COLUMN y float8 GENERATED ALWAYS AS (d * 4) STORED;
+  ADD COLUMN y float8 GENERATED ALWAYS AS (d * 4) VIRTUAL;
 SELECT * FROM gtest25 ORDER BY a;
 \d gtest25
 
@@ -479,7 +486,7 @@ CREATE TABLE gtest25 (a int PRIMARY KEY);
 CREATE TABLE gtest27 (
     a int,
     b int,
-    x int GENERATED ALWAYS AS ((a + b) * 2) STORED
+    x int GENERATED ALWAYS AS ((a + b) * 2) VIRTUAL
 );
 INSERT INTO gtest27 (a, b) VALUES (3, 7), (4, 11);
 ALTER TABLE gtest27 ALTER COLUMN a TYPE text;  -- error
@@ -493,7 +500,7 @@ CREATE TABLE gtest27 (
   DROP COLUMN x,
   ALTER COLUMN a TYPE bigint,
   ALTER COLUMN b TYPE bigint,
-  ADD COLUMN x bigint GENERATED ALWAYS AS ((a + b) * 2) STORED;
+  ADD COLUMN x bigint GENERATED ALWAYS AS ((a + b) * 2) VIRTUAL;
 \d gtest27
 -- Ideally you could just do this, but not today (and should x change type?):
 ALTER TABLE gtest27
@@ -505,7 +512,7 @@ CREATE TABLE gtest27 (
 -- ALTER TABLE ... ALTER COLUMN ... DROP EXPRESSION
 CREATE TABLE gtest29 (
     a int,
-    b int GENERATED ALWAYS AS (a * 2) STORED
+    b int GENERATED ALWAYS AS (a * 2) VIRTUAL
 );
 INSERT INTO gtest29 (a) VALUES (3), (4);
 SELECT * FROM gtest29;
@@ -532,7 +539,7 @@ CREATE TABLE gtest29 (
 -- with inheritance
 CREATE TABLE gtest30 (
     a int,
-    b int GENERATED ALWAYS AS (a * 2) STORED
+    b int GENERATED ALWAYS AS (a * 2) VIRTUAL
 );
 CREATE TABLE gtest30_1 () INHERITS (gtest30);
 ALTER TABLE gtest30 ALTER COLUMN b DROP EXPRESSION;
@@ -541,7 +548,7 @@ CREATE TABLE gtest30_1 () INHERITS (gtest30);
 DROP TABLE gtest30 CASCADE;
 CREATE TABLE gtest30 (
     a int,
-    b int GENERATED ALWAYS AS (a * 2) STORED
+    b int GENERATED ALWAYS AS (a * 2) VIRTUAL
 );
 CREATE TABLE gtest30_1 () INHERITS (gtest30);
 ALTER TABLE ONLY gtest30 ALTER COLUMN b DROP EXPRESSION;  -- error
@@ -552,7 +559,7 @@ CREATE TABLE gtest30_1 () INHERITS (gtest30);
 -- triggers
 CREATE TABLE gtest26 (
     a int PRIMARY KEY,
-    b int GENERATED ALWAYS AS (a * 2) STORED
+    b int GENERATED ALWAYS AS (a * 2) VIRTUAL
 );
 
 CREATE FUNCTION gtest_trigger_func() RETURNS trigger
@@ -614,6 +621,9 @@ CREATE TRIGGER gtest4 AFTER INSERT OR UPDATE ON gtest26
 DROP TRIGGER gtest2 ON gtest26;
 DROP TRIGGER gtest3 ON gtest26;
 
+-- check disallowed modification of virtual columns
+-- TODO
+
 -- Check that an UPDATE of "a" fires the trigger for UPDATE OF b, per
 -- SQL standard.
 CREATE FUNCTION gtest_trigger_func3() RETURNS trigger
@@ -667,7 +677,7 @@ CREATE TABLE gtest28a (
   a int,
   b int,
   c int,
-  x int GENERATED ALWAYS AS (b * 2) STORED
+  x int GENERATED ALWAYS AS (b * 2) VIRTUAL
 );
 
 ALTER TABLE gtest28a DROP COLUMN a;
diff --git a/src/test/subscription/t/011_generated.pl b/src/test/subscription/t/011_generated.pl
index 8b2e5f4708e..faee155daa7 100644
--- a/src/test/subscription/t/011_generated.pl
+++ b/src/test/subscription/t/011_generated.pl
@@ -21,11 +21,11 @@
 my $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
 
 $node_publisher->safe_psql('postgres',
-	"CREATE TABLE tab1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED)"
+	"CREATE TABLE tab1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) STORED, c int GENERATED ALWAYS AS (a * 3) VIRTUAL)"
 );
 
 $node_subscriber->safe_psql('postgres',
-	"CREATE TABLE tab1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 22) STORED, c int)"
+	"CREATE TABLE tab1 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 22) STORED, c int GENERATED ALWAYS AS (a * 33) VIRTUAL, d int)"
 );
 
 # data for initial sync
@@ -42,10 +42,10 @@
 # Wait for initial sync of all subscriptions
 $node_subscriber->wait_for_subscription_sync;
 
-my $result = $node_subscriber->safe_psql('postgres', "SELECT a, b FROM tab1");
-is( $result, qq(1|22
-2|44
-3|66), 'generated columns initial sync');
+my $result = $node_subscriber->safe_psql('postgres', "SELECT a, b, c FROM tab1");
+is( $result, qq(1|22|33
+2|44|66
+3|66|99), 'generated columns initial sync');
 
 # data to replicate
 
@@ -56,11 +56,11 @@
 $node_publisher->wait_for_catchup('sub1');
 
 $result = $node_subscriber->safe_psql('postgres', "SELECT * FROM tab1");
-is( $result, qq(1|22|
-2|44|
-3|66|
-4|88|
-6|132|), 'generated columns replicated');
+is( $result, qq(1|22|33|
+2|44|66|
+3|66|99|
+4|88|132|
+6|132|198|), 'generated columns replicated');
 
 # try it with a subscriber-side trigger
 
@@ -69,7 +69,7 @@
 CREATE FUNCTION tab1_trigger_func() RETURNS trigger
 LANGUAGE plpgsql AS $$
 BEGIN
-  NEW.c := NEW.a + 10;
+  NEW.d := NEW.a + 10;
   RETURN NEW;
 END $$;
 
@@ -88,12 +88,12 @@ BEGIN
 
 $result =
   $node_subscriber->safe_psql('postgres', "SELECT * FROM tab1 ORDER BY 1");
-is( $result, qq(1|22|
-2|44|
-3|66|
-4|88|
-6|132|
-8|176|18
-9|198|19), 'generated columns replicated with trigger');
+is( $result, qq(1|22|33|
+2|44|66|
+3|66|99|
+4|88|132|
+6|132|198|
+8|176|264|18
+9|198|297|19), 'generated columns replicated with trigger');
 
 done_testing();
-- 
2.44.0

---

From: Tomasz Rybak <[email-masked]>
Date: Mon, 17 Jun 2024 21:31:18 +0200

> for now, with the idea that some of these things can be added in

This is not (yet) full review.

Patches applied cleanly on 76618097a6c027ec603a3dd143f61098e3fb9794
from 2024-06-14.
I've run
./configure && make world-bin && make check && make check-world
on 0001, then 0001+0002, then 0001+0002+0003, up to applying
all 5 patches. All cases passed on Debian unstable on aarch64 (ARM64)
on gcc (Debian 13.2.0-25) 13.2.0.

v1-0001-Rename-regress-test-generated-to-generated_stored.patch:
no objections here, makes sense as preparation for future changes

v1-0002-Put-generated_stored-test-objects-in-a-schema.patch:
also no objections.
OTOH other tests (like publication.out, rowsecurity.out, stats_ext.out,
tablespace.out) are creating schemas and later dropping them - so here
it might also make sense to drop schema at the end of testing.

v1-0003-Remove-useless-initializations.patch:
All other cases (I checked directory src/backend/utils/cache)
calling MemoryContextAllocZero only initialize fields when they
are non-zero, so removing partial initialization with false brings
consistency to the code.

v1-0004-Remove-useless-code.patch:
Patch removes filling in of constraints from function
BuildDescForRelation. This function is only called from file
view.c and tablecmds.c (twice). In none of those cases
result->constr is used, so proposed change makes sense.
While I do not know code well, so might be wrong here,
I would apply this patch.

I haven't looked at the most important (and biggest) file yet,
v1-0005-Virtual-generated-columns.patch; hope to look at it
this week.
At the same I believe 0001-0004 can be applied - even backported
if it'll make maintenance of future changes easier. But that should
be commiter's decision.

Best regards

-- 
Tomasz Rybak, Debian Developer <[email-masked]>
GPG: A565 CE64 F866 A258 4DDC F9C7 ECB7 3E37 E887 AA8C

---

From: jian he <[email-masked]>
Date: Fri, 28 Jun 2024 08:00:00 +0800

> > structure, so I don't have to keep changing it around later.

the test structure you made ( generated_stored.sql,
generated_virtual.sq) looks ok to me.
but do we need to reset the search_path at the end of
generated_stored.sql, generated_virtual.sql?

most of the test tables didn't use much storage,
maybe not necessary to clean up (drop the test table) at the end of sql files.

> tell me what in fact doesn't work correctly, that would be helpful.

in https://www.postgresql.org/docs/current/catalog-pg-attrdef.html
The catalog pg_attrdef stores column default values. The main
information about columns is stored in pg_attribute. Only columns for
which a default value has been explicitly set will have an entry here.
didn't mention generated columns related expressions.
Do we need to add something here? maybe a separate issue?

+ /*
+ errmsg("ALTER TABLE / SET EXPRESSION is not supported for virtual
generated columns"),

minor typo, should be
+ errmsg("ALTER TABLE SET EXPRESSION is not supported for virtual
generated columns"),

insert/update/delete/merge returning have problems:
CREATE TABLE t2 (
a int ,
b int GENERATED ALWAYS AS (a * 2),
d int default 22);
insert into t2(a) select g from generate_series(1,10) g;

insert into t2 select 100 returning *, (select t2.b), t2.b = t2.a * 2;
update t2 set a = 12 returning *, (select t2.b), t2.b = t2.a * 2;
update t2 set a = 12 returning *, (select (select t2.b)), t2.b = t2.a * 2;
delete from t2 where t2.b = t2.a * 2 returning *, 1,((select t2.b));

currently all these query, error message is "unexpected virtual
generated column reference"
we expect above these query work?

issue with merge:
CREATE TABLE t0 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (a * 2) VIRTUAL);
insert into t0(a) select g from generate_series(1,10) g;
MERGE INTO t0 t USING t0 AS s ON 2 * t.a = s.b WHEN MATCHED THEN
DELETE returning *;

the above query returns zero rows, but for stored generated columns it
will return 10 rows.

in  transformMergeStmt(ParseState *pstate, MergeStmt *stmt)
add
`qry->hasGeneratedVirtual = pstate->p_hasGeneratedVirtual;`
before
`assign_query_collations(pstate, qry);`
solve the problem.

---

From: Peter Eisentraut <[email-masked]>
Date: Mon, 1 Jul 2024 09:06:46 +0200

On 28.06.24 02:00, jian he wrote:
> inhttps://www.postgresql.org/docs/current/catalog-pg-attrdef.html

Yes and yes.  I have committed a separate change to update the 
documentation here.