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MERGE performs actions that modify rows in the target table using a source table or query. MERGE provides a single SQL statement that can conditionally INSERT/UPDATE/DELETE rows a task that would other require multiple PL statements. e.g. MERGE INTO target AS t USING source AS s ON t.tid = s.sid WHEN MATCHED AND t.balance > s.delta THEN UPDATE SET balance = t.balance - s.delta WHEN MATCHED THEN DELETE WHEN NOT MATCHED AND s.delta > 0 THEN INSERT VALUES (s.sid, s.delta) WHEN NOT MATCHED THEN DO NOTHING; MERGE works with regular and partitioned tables, including column and row security enforcement, as well as support for row, statement and transition triggers. MERGE is optimized for OLTP and is parameterizable, though also useful for large scale ETL/ELT. MERGE is not intended to be used in preference to existing single SQL commands for INSERT, UPDATE or DELETE since there is some overhead. MERGE can be used statically from PL/pgSQL. MERGE does not yet support inheritance, write rules, RETURNING clauses, updatable views or foreign tables. MERGE follows SQL Standard per the most recent SQL:2016. Includes full tests and documentation, including full isolation tests to demonstrate the concurrent behavior. This version written from scratch in 2017 by Simon Riggs, using docs and tests originally written in 2009. Later work from Pavan Deolasee has been both complex and deep, leaving the lead author credit now in his hands. Extensive discussion of concurrency from Peter Geoghegan, with thanks for the time and effort contributed. Various issues reported via sqlsmith by Andreas Seltenreich Authors: Pavan Deolasee, Simon Riggs Reviewer: Peter Geoghegan, Amit Langote, Tomas Vondra, Simon Riggs Discussion: https://postgr.es/m/CANP8+jKitBSrB7oTgT9CY2i1ObfOt36z0XMraQc+Xrz8QB0nXA@mail.gmail.com https://postgr.es/m/CAH2-WzkJdBuxj9PO=2QaO9-3h3xGbQPZ34kJH=HukRekwM-GZg@mail.gmail.com
294 lines
8.7 KiB
SQL
294 lines
8.7 KiB
SQL
-- sanity check of system catalog
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SELECT attrelid, attname, attidentity FROM pg_attribute WHERE attidentity NOT IN ('', 'a', 'd');
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CREATE TABLE itest1 (a int generated by default as identity, b text);
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CREATE TABLE itest2 (a bigint generated always as identity, b text);
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CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
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ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; -- error
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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;
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-- internal sequences should not be shown here
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SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
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SELECT pg_get_serial_sequence('itest1', 'a');
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\d itest1_a_seq
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CREATE TABLE itest4 (a int, b text);
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ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; -- error, requires NOT NULL
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ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
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ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; -- ok
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ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL; -- error, disallowed
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ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY; -- error, already set
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ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY; -- error, wrong data type
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-- for later
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ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
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-- invalid column type
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CREATE TABLE itest_err_1 (a text generated by default as identity);
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-- duplicate identity
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CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
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-- cannot have default and identity
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CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
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-- cannot combine serial and identity
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CREATE TABLE itest_err_4 (a serial generated by default as identity);
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INSERT INTO itest1 DEFAULT VALUES;
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INSERT INTO itest1 DEFAULT VALUES;
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INSERT INTO itest2 DEFAULT VALUES;
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INSERT INTO itest2 DEFAULT VALUES;
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INSERT INTO itest3 DEFAULT VALUES;
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INSERT INTO itest3 DEFAULT VALUES;
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INSERT INTO itest4 DEFAULT VALUES;
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INSERT INTO itest4 DEFAULT VALUES;
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SELECT * FROM itest1;
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SELECT * FROM itest2;
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SELECT * FROM itest3;
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SELECT * FROM itest4;
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-- VALUES RTEs
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INSERT INTO itest3 VALUES (DEFAULT, 'a');
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INSERT INTO itest3 VALUES (DEFAULT, 'b'), (DEFAULT, 'c');
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SELECT * FROM itest3;
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-- OVERRIDING tests
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INSERT INTO itest1 VALUES (10, 'xyz');
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INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
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SELECT * FROM itest1;
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INSERT INTO itest2 VALUES (10, 'xyz');
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INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
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SELECT * FROM itest2;
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-- UPDATE tests
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UPDATE itest1 SET a = 101 WHERE a = 1;
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UPDATE itest1 SET a = DEFAULT WHERE a = 2;
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SELECT * FROM itest1;
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UPDATE itest2 SET a = 101 WHERE a = 1;
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UPDATE itest2 SET a = DEFAULT WHERE a = 2;
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SELECT * FROM itest2;
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-- COPY tests
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CREATE TABLE itest9 (a int GENERATED ALWAYS AS IDENTITY, b text, c bigint);
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COPY itest9 FROM stdin;
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100 foo 200
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101 bar 201
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\.
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COPY itest9 (b, c) FROM stdin;
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foo2 202
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bar2 203
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\.
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SELECT * FROM itest9 ORDER BY c;
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-- DROP IDENTITY tests
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ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
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ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY; -- error
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ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY IF EXISTS; -- noop
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INSERT INTO itest4 DEFAULT VALUES; -- fails because NOT NULL is not dropped
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ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;
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INSERT INTO itest4 DEFAULT VALUES;
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SELECT * FROM itest4;
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-- check that sequence is removed
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SELECT sequence_name FROM itest4_a_seq;
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-- test views
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CREATE TABLE itest10 (a int generated by default as identity, b text);
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CREATE TABLE itest11 (a int generated always as identity, b text);
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CREATE VIEW itestv10 AS SELECT * FROM itest10;
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CREATE VIEW itestv11 AS SELECT * FROM itest11;
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INSERT INTO itestv10 DEFAULT VALUES;
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INSERT INTO itestv10 DEFAULT VALUES;
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INSERT INTO itestv11 DEFAULT VALUES;
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INSERT INTO itestv11 DEFAULT VALUES;
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SELECT * FROM itestv10;
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SELECT * FROM itestv11;
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INSERT INTO itestv10 VALUES (10, 'xyz');
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INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
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SELECT * FROM itestv10;
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INSERT INTO itestv11 VALUES (10, 'xyz');
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INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
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SELECT * FROM itestv11;
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-- ADD COLUMN
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CREATE TABLE itest13 (a int);
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-- add column to empty table
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ALTER TABLE itest13 ADD COLUMN b int GENERATED BY DEFAULT AS IDENTITY;
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INSERT INTO itest13 VALUES (1), (2), (3);
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-- add column to populated table
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ALTER TABLE itest13 ADD COLUMN c int GENERATED BY DEFAULT AS IDENTITY;
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SELECT * FROM itest13;
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-- various ALTER COLUMN tests
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-- fail, not allowed for identity columns
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ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
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-- fail, not allowed, already has a default
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CREATE TABLE itest5 (a serial, b text);
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ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
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ALTER TABLE itest3 ALTER COLUMN a TYPE int;
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SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass;
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\d itest3
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ALTER TABLE itest3 ALTER COLUMN a TYPE text; -- error
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-- ALTER COLUMN ... SET
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CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
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INSERT INTO itest6 DEFAULT VALUES;
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ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
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INSERT INTO itest6 DEFAULT VALUES;
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INSERT INTO itest6 DEFAULT VALUES;
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SELECT * FROM itest6;
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SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
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ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2; -- fail, not identity
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-- prohibited direct modification of sequence
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ALTER SEQUENCE itest6_a_seq OWNED BY NONE;
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-- inheritance
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CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
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INSERT INTO itest7 DEFAULT VALUES;
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SELECT * FROM itest7;
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-- identity property is not inherited
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CREATE TABLE itest7a (b text) INHERITS (itest7);
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-- make column identity in child table
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CREATE TABLE itest7b (a int);
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CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
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INSERT INTO itest7c DEFAULT VALUES;
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SELECT * FROM itest7c;
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CREATE TABLE itest7d (a int not null);
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CREATE TABLE itest7e () INHERITS (itest7d);
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ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
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ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY; -- error
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SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
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-- These ALTER TABLE variants will not recurse.
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ALTER TABLE itest7 ALTER COLUMN a SET GENERATED BY DEFAULT;
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ALTER TABLE itest7 ALTER COLUMN a RESTART;
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ALTER TABLE itest7 ALTER COLUMN a DROP IDENTITY;
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-- privileges
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CREATE USER regress_identity_user1;
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CREATE TABLE itest8 (a int GENERATED ALWAYS AS IDENTITY, b text);
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GRANT SELECT, INSERT ON itest8 TO regress_identity_user1;
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SET ROLE regress_identity_user1;
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INSERT INTO itest8 DEFAULT VALUES;
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SELECT * FROM itest8;
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RESET ROLE;
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DROP TABLE itest8;
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DROP USER regress_identity_user1;
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-- typed tables (currently not supported)
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CREATE TYPE itest_type AS (f1 integer, f2 text, f3 bigint);
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CREATE TABLE itest12 OF itest_type (f1 WITH OPTIONS GENERATED ALWAYS AS IDENTITY); -- error
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DROP TYPE itest_type CASCADE;
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-- table partitions (currently not supported)
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CREATE TABLE itest_parent (f1 date NOT NULL, f2 text, f3 bigint) PARTITION BY RANGE (f1);
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CREATE TABLE itest_child PARTITION OF itest_parent (
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f3 WITH OPTIONS GENERATED ALWAYS AS IDENTITY
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) FOR VALUES FROM ('2016-07-01') TO ('2016-08-01'); -- error
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DROP TABLE itest_parent;
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-- MERGE tests
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CREATE TABLE itest14 (a int GENERATED ALWAYS AS IDENTITY, b text);
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CREATE TABLE itest15 (a int GENERATED BY DEFAULT AS IDENTITY, b text);
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MERGE INTO itest14 t
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USING (SELECT 10 AS s_a, 'inserted by merge' AS s_b) s
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ON t.a = s.s_a
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WHEN NOT MATCHED THEN
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INSERT (a, b) VALUES (s.s_a, s.s_b);
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MERGE INTO itest14 t
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USING (SELECT 20 AS s_a, 'inserted by merge' AS s_b) s
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ON t.a = s.s_a
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WHEN NOT MATCHED THEN
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INSERT (a, b) OVERRIDING USER VALUE VALUES (s.s_a, s.s_b);
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MERGE INTO itest14 t
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USING (SELECT 30 AS s_a, 'inserted by merge' AS s_b) s
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ON t.a = s.s_a
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WHEN NOT MATCHED THEN
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INSERT (a, b) OVERRIDING SYSTEM VALUE VALUES (s.s_a, s.s_b);
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MERGE INTO itest15 t
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USING (SELECT 10 AS s_a, 'inserted by merge' AS s_b) s
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ON t.a = s.s_a
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WHEN NOT MATCHED THEN
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INSERT (a, b) VALUES (s.s_a, s.s_b);
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MERGE INTO itest15 t
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USING (SELECT 20 AS s_a, 'inserted by merge' AS s_b) s
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ON t.a = s.s_a
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WHEN NOT MATCHED THEN
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INSERT (a, b) OVERRIDING USER VALUE VALUES (s.s_a, s.s_b);
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MERGE INTO itest15 t
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USING (SELECT 30 AS s_a, 'inserted by merge' AS s_b) s
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ON t.a = s.s_a
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WHEN NOT MATCHED THEN
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INSERT (a, b) OVERRIDING SYSTEM VALUE VALUES (s.s_a, s.s_b);
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SELECT * FROM itest14;
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SELECT * FROM itest15;
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DROP TABLE itest14;
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DROP TABLE itest15;
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