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168d5805e4
The newly added ON CONFLICT clause allows to specify an alternative to
raising a unique or exclusion constraint violation error when inserting.
ON CONFLICT refers to constraints that can either be specified using a
inference clause (by specifying the columns of a unique constraint) or
by naming a unique or exclusion constraint. DO NOTHING avoids the
constraint violation, without touching the pre-existing row. DO UPDATE
SET ... [WHERE ...] updates the pre-existing tuple, and has access to
both the tuple proposed for insertion and the existing tuple; the
optional WHERE clause can be used to prevent an update from being
executed. The UPDATE SET and WHERE clauses have access to the tuple
proposed for insertion using the "magic" EXCLUDED alias, and to the
pre-existing tuple using the table name or its alias.
This feature is often referred to as upsert.
This is implemented using a new infrastructure called "speculative
insertion". It is an optimistic variant of regular insertion that first
does a pre-check for existing tuples and then attempts an insert. If a
violating tuple was inserted concurrently, the speculatively inserted
tuple is deleted and a new attempt is made. If the pre-check finds a
matching tuple the alternative DO NOTHING or DO UPDATE action is taken.
If the insertion succeeds without detecting a conflict, the tuple is
deemed inserted.
To handle the possible ambiguity between the excluded alias and a table
named excluded, and for convenience with long relation names, INSERT
INTO now can alias its target table.
Bumps catversion as stored rules change.
Author: Peter Geoghegan, with significant contributions from Heikki
Linnakangas and Andres Freund. Testing infrastructure by Jeff Janes.
Reviewed-By: Heikki Linnakangas, Andres Freund, Robert Haas, Simon Riggs,
Dean Rasheed, Stephen Frost and many others.
98 lines
2.8 KiB
SQL
98 lines
2.8 KiB
SQL
--
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-- UPDATE syntax tests
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--
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CREATE TABLE update_test (
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a INT DEFAULT 10,
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b INT,
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c TEXT
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);
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CREATE TABLE upsert_test (
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a INT PRIMARY KEY,
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b TEXT
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);
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INSERT INTO update_test VALUES (5, 10, 'foo');
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INSERT INTO update_test(b, a) VALUES (15, 10);
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SELECT * FROM update_test;
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UPDATE update_test SET a = DEFAULT, b = DEFAULT;
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SELECT * FROM update_test;
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-- aliases for the UPDATE target table
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UPDATE update_test AS t SET b = 10 WHERE t.a = 10;
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SELECT * FROM update_test;
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UPDATE update_test t SET b = t.b + 10 WHERE t.a = 10;
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SELECT * FROM update_test;
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--
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-- Test VALUES in FROM
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--
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UPDATE update_test SET a=v.i FROM (VALUES(100, 20)) AS v(i, j)
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WHERE update_test.b = v.j;
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SELECT * FROM update_test;
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--
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-- Test multiple-set-clause syntax
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--
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INSERT INTO update_test SELECT a,b+1,c FROM update_test;
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SELECT * FROM update_test;
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UPDATE update_test SET (c,b,a) = ('bugle', b+11, DEFAULT) WHERE c = 'foo';
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SELECT * FROM update_test;
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UPDATE update_test SET (c,b) = ('car', a+b), a = a + 1 WHERE a = 10;
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SELECT * FROM update_test;
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-- fail, multi assignment to same column:
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UPDATE update_test SET (c,b) = ('car', a+b), b = a + 1 WHERE a = 10;
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-- uncorrelated sub-select:
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UPDATE update_test
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SET (b,a) = (select a,b from update_test where b = 41 and c = 'car')
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WHERE a = 100 AND b = 20;
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SELECT * FROM update_test;
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-- correlated sub-select:
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UPDATE update_test o
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SET (b,a) = (select a+1,b from update_test i
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where i.a=o.a and i.b=o.b and i.c is not distinct from o.c);
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SELECT * FROM update_test;
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-- fail, multiple rows supplied:
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UPDATE update_test SET (b,a) = (select a+1,b from update_test);
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-- set to null if no rows supplied:
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UPDATE update_test SET (b,a) = (select a+1,b from update_test where a = 1000)
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WHERE a = 11;
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SELECT * FROM update_test;
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-- if an alias for the target table is specified, don't allow references
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-- to the original table name
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UPDATE update_test AS t SET b = update_test.b + 10 WHERE t.a = 10;
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-- Make sure that we can update to a TOASTed value.
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UPDATE update_test SET c = repeat('x', 10000) WHERE c = 'car';
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SELECT a, b, char_length(c) FROM update_test;
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-- Test ON CONFLICT DO UPDATE
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INSERT INTO upsert_test VALUES(1, 'Boo');
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-- uncorrelated sub-select:
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WITH aaa AS (SELECT 1 AS a, 'Foo' AS b) INSERT INTO upsert_test
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VALUES (1, 'Bar') ON CONFLICT(a)
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DO UPDATE SET (b, a) = (SELECT b, a FROM aaa) RETURNING *;
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-- correlated sub-select:
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INSERT INTO upsert_test VALUES (1, 'Baz') ON CONFLICT(a)
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DO UPDATE SET (b, a) = (SELECT b || ', Correlated', a from upsert_test i WHERE i.a = upsert_test.a)
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RETURNING *;
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-- correlated sub-select (EXCLUDED.* alias):
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INSERT INTO upsert_test VALUES (1, 'Bat') ON CONFLICT(a)
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DO UPDATE SET (b, a) = (SELECT b || ', Excluded', a from upsert_test i WHERE i.a = excluded.a)
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RETURNING *;
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DROP TABLE update_test;
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DROP TABLE upsert_test;
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