-- sanity check of system catalog SELECT attrelid, attname, attidentity FROM pg_attribute WHERE attidentity NOT IN ('', 'a', 'd'); attrelid | attname | attidentity ----------+---------+------------- (0 rows) CREATE TABLE itest1 (a int generated by default as identity, b text); CREATE TABLE itest2 (a bigint generated always as identity, b text); CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text); ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; -- error ERROR: column "a" of relation "itest3" is already an identity column SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2; table_name | column_name | column_default | is_nullable | is_identity | identity_generation | identity_start | identity_increment | identity_maximum | identity_minimum | identity_cycle ------------+-------------+----------------+-------------+-------------+---------------------+----------------+--------------------+---------------------+------------------+---------------- itest1 | a | | NO | YES | BY DEFAULT | 1 | 1 | 2147483647 | 1 | NO itest1 | b | | YES | NO | | | | | | NO itest2 | a | | NO | YES | ALWAYS | 1 | 1 | 9223372036854775807 | 1 | NO itest2 | b | | YES | NO | | | | | | NO itest3 | a | | NO | YES | BY DEFAULT | 7 | 5 | 32767 | 1 | NO itest3 | b | | YES | NO | | | | | | NO (6 rows) -- internal sequences should not be shown here SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%'; sequence_name --------------- (0 rows) SELECT pg_get_serial_sequence('itest1', 'a'); pg_get_serial_sequence ------------------------ public.itest1_a_seq (1 row) \d itest1_a_seq Sequence "public.itest1_a_seq" Type | Start | Minimum | Maximum | Increment | Cycles? | Cache ---------+-------+---------+------------+-----------+---------+------- integer | 1 | 1 | 2147483647 | 1 | no | 1 Sequence for identity column: public.itest1.a CREATE TABLE itest4 (a int, b text); ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; -- error, requires NOT NULL ERROR: column "a" of relation "itest4" must be declared NOT NULL before identity can be added ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL; ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; -- ok ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL; -- error, disallowed ERROR: column "a" of relation "itest4" is an identity column ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; -- error, already set ERROR: column "a" of relation "itest4" is already an identity column ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY; -- error, wrong data type ERROR: identity column type must be smallint, integer, or bigint -- for later ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT ''; -- invalid column type CREATE TABLE itest_err_1 (a text generated by default as identity); ERROR: identity column type must be smallint, integer, or bigint -- duplicate identity CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity); ERROR: multiple identity specifications for column "a" of table "itest_err_2" LINE 1: ...E itest_err_2 (a int generated always as identity generated ... ^ -- cannot have default and identity CREATE TABLE itest_err_3 (a int default 5 generated by default as identity); ERROR: both default and identity specified for column "a" of table "itest_err_3" LINE 1: CREATE TABLE itest_err_3 (a int default 5 generated by defau... ^ -- cannot combine serial and identity CREATE TABLE itest_err_4 (a serial generated by default as identity); ERROR: both default and identity specified for column "a" of table "itest_err_4" INSERT INTO itest1 DEFAULT VALUES; INSERT INTO itest1 DEFAULT VALUES; INSERT INTO itest2 DEFAULT VALUES; INSERT INTO itest2 DEFAULT VALUES; INSERT INTO itest3 DEFAULT VALUES; INSERT INTO itest3 DEFAULT VALUES; INSERT INTO itest4 DEFAULT VALUES; INSERT INTO itest4 DEFAULT VALUES; SELECT * FROM itest1; a | b ---+--- 1 | 2 | (2 rows) SELECT * FROM itest2; a | b ---+--- 1 | 2 | (2 rows) SELECT * FROM itest3; a | b ----+--- 7 | 12 | (2 rows) SELECT * FROM itest4; a | b ---+--- 1 | 2 | (2 rows) -- VALUES RTEs INSERT INTO itest3 VALUES (DEFAULT, 'a'); INSERT INTO itest3 VALUES (DEFAULT, 'b'), (DEFAULT, 'c'); SELECT * FROM itest3; a | b ----+--- 7 | 12 | 17 | a 22 | b 27 | c (5 rows) -- OVERRIDING tests INSERT INTO itest1 VALUES (10, 'xyz'); INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz'); SELECT * FROM itest1; a | b ----+----- 1 | 2 | 10 | xyz 3 | xyz (4 rows) INSERT INTO itest2 VALUES (10, 'xyz'); ERROR: cannot insert into column "a" DETAIL: Column "a" is an identity column defined as GENERATED ALWAYS. HINT: Use OVERRIDING SYSTEM VALUE to override. INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz'); SELECT * FROM itest2; a | b ----+----- 1 | 2 | 10 | xyz (3 rows) -- UPDATE tests UPDATE itest1 SET a = 101 WHERE a = 1; UPDATE itest1 SET a = DEFAULT WHERE a = 2; SELECT * FROM itest1; a | b -----+----- 10 | xyz 3 | xyz 101 | 4 | (4 rows) UPDATE itest2 SET a = 101 WHERE a = 1; ERROR: column "a" can only be updated to DEFAULT DETAIL: Column "a" is an identity column defined as GENERATED ALWAYS. UPDATE itest2 SET a = DEFAULT WHERE a = 2; SELECT * FROM itest2; a | b ----+----- 1 | 10 | xyz 3 | (3 rows) -- COPY tests CREATE TABLE itest9 (a int GENERATED ALWAYS AS IDENTITY, b text, c bigint); COPY itest9 FROM stdin; COPY itest9 (b, c) FROM stdin; SELECT * FROM itest9 ORDER BY c; a | b | c -----+------+----- 100 | foo | 200 101 | bar | 201 1 | foo2 | 202 2 | bar2 | 203 (4 rows) -- DROP IDENTITY tests ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY; ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY; -- error ERROR: column "a" of relation "itest4" is not an identity column ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY IF EXISTS; -- noop NOTICE: column "a" of relation "itest4" is not an identity column, skipping INSERT INTO itest4 DEFAULT VALUES; -- fails because NOT NULL is not dropped ERROR: null value in column "a" violates not-null constraint DETAIL: Failing row contains (null, ). ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL; INSERT INTO itest4 DEFAULT VALUES; SELECT * FROM itest4; a | b ---+--- 1 | 2 | | (3 rows) -- check that sequence is removed SELECT sequence_name FROM itest4_a_seq; ERROR: relation "itest4_a_seq" does not exist LINE 1: SELECT sequence_name FROM itest4_a_seq; ^ -- test views CREATE TABLE itest10 (a int generated by default as identity, b text); CREATE TABLE itest11 (a int generated always as identity, b text); CREATE VIEW itestv10 AS SELECT * FROM itest10; CREATE VIEW itestv11 AS SELECT * FROM itest11; INSERT INTO itestv10 DEFAULT VALUES; INSERT INTO itestv10 DEFAULT VALUES; INSERT INTO itestv11 DEFAULT VALUES; INSERT INTO itestv11 DEFAULT VALUES; SELECT * FROM itestv10; a | b ---+--- 1 | 2 | (2 rows) SELECT * FROM itestv11; a | b ---+--- 1 | 2 | (2 rows) INSERT INTO itestv10 VALUES (10, 'xyz'); INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz'); SELECT * FROM itestv10; a | b ----+----- 1 | 2 | 10 | xyz 3 | xyz (4 rows) INSERT INTO itestv11 VALUES (10, 'xyz'); ERROR: cannot insert into column "a" DETAIL: Column "a" is an identity column defined as GENERATED ALWAYS. HINT: Use OVERRIDING SYSTEM VALUE to override. INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz'); SELECT * FROM itestv11; a | b ----+----- 1 | 2 | 11 | xyz (3 rows) DROP VIEW itestv10, itestv11; -- ADD COLUMN CREATE TABLE itest13 (a int); -- add column to empty table ALTER TABLE itest13 ADD COLUMN b int GENERATED BY DEFAULT AS IDENTITY; INSERT INTO itest13 VALUES (1), (2), (3); -- add column to populated table ALTER TABLE itest13 ADD COLUMN c int GENERATED BY DEFAULT AS IDENTITY; SELECT * FROM itest13; a | b | c ---+---+--- 1 | 1 | 1 2 | 2 | 2 3 | 3 | 3 (3 rows) -- various ALTER COLUMN tests -- fail, not allowed for identity columns ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1; ERROR: column "a" of relation "itest1" is an identity column -- fail, not allowed, already has a default CREATE TABLE itest5 (a serial, b text); ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; ERROR: column "a" of relation "itest5" already has a default value ALTER TABLE itest3 ALTER COLUMN a TYPE int; SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass; seqtypid ---------- integer (1 row) \d itest3 Table "public.itest3" Column | Type | Collation | Nullable | Default --------+---------+-----------+----------+---------------------------------- a | integer | | not null | generated by default as identity b | text | | | ALTER TABLE itest3 ALTER COLUMN a TYPE text; -- error ERROR: identity column type must be smallint, integer, or bigint -- ALTER COLUMN ... SET CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text); INSERT INTO itest6 DEFAULT VALUES; ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART; INSERT INTO itest6 DEFAULT VALUES; INSERT INTO itest6 DEFAULT VALUES; SELECT * FROM itest6; a | b -----+--- 1 | 100 | 102 | (3 rows) SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6'; table_name | column_name | is_identity | identity_generation ------------+-------------+-------------+--------------------- itest6 | a | YES | BY DEFAULT itest6 | b | NO | (2 rows) ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2; -- fail, not identity ERROR: column "b" of relation "itest6" is not an identity column -- prohibited direct modification of sequence ALTER SEQUENCE itest6_a_seq OWNED BY NONE; ERROR: cannot change ownership of identity sequence DETAIL: Sequence "itest6_a_seq" is linked to table "itest6". -- inheritance CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY); INSERT INTO itest7 DEFAULT VALUES; SELECT * FROM itest7; a --- 1 (1 row) -- identity property is not inherited CREATE TABLE itest7a (b text) INHERITS (itest7); -- make column identity in child table CREATE TABLE itest7b (a int); CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b); NOTICE: merging column "a" with inherited definition INSERT INTO itest7c DEFAULT VALUES; SELECT * FROM itest7c; a --- 1 (1 row) CREATE TABLE itest7d (a int not null); CREATE TABLE itest7e () INHERITS (itest7d); ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY; -- error ERROR: cannot recursively add identity column to table that has child tables SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2; table_name | column_name | is_nullable | is_identity | identity_generation ------------+-------------+-------------+-------------+--------------------- itest7 | a | NO | YES | ALWAYS itest7a | a | NO | NO | itest7a | b | YES | NO | itest7b | a | YES | NO | itest7c | a | NO | YES | ALWAYS itest7d | a | NO | YES | ALWAYS itest7e | a | NO | NO | (7 rows) -- These ALTER TABLE variants will not recurse. ALTER TABLE itest7 ALTER COLUMN a SET GENERATED BY DEFAULT; ALTER TABLE itest7 ALTER COLUMN a RESTART; ALTER TABLE itest7 ALTER COLUMN a DROP IDENTITY; -- privileges CREATE USER regress_identity_user1; CREATE TABLE itest8 (a int GENERATED ALWAYS AS IDENTITY, b text); GRANT SELECT, INSERT ON itest8 TO regress_identity_user1; SET ROLE regress_identity_user1; INSERT INTO itest8 DEFAULT VALUES; SELECT * FROM itest8; a | b ---+--- 1 | (1 row) RESET ROLE; DROP TABLE itest8; DROP USER regress_identity_user1; -- typed tables (currently not supported) CREATE TYPE itest_type AS (f1 integer, f2 text, f3 bigint); CREATE TABLE itest12 OF itest_type (f1 WITH OPTIONS GENERATED ALWAYS AS IDENTITY); -- error ERROR: identity columns are not supported on typed tables DROP TYPE itest_type CASCADE; -- table partitions (currently not supported) CREATE TABLE itest_parent (f1 date NOT NULL, f2 text, f3 bigint) PARTITION BY RANGE (f1); CREATE TABLE itest_child PARTITION OF itest_parent ( f3 WITH OPTIONS GENERATED ALWAYS AS IDENTITY ) FOR VALUES FROM ('2016-07-01') TO ('2016-08-01'); -- error ERROR: identity columns are not supported on partitions DROP TABLE itest_parent;