# INSERT ... ON CONFLICT test verifying that speculative insertion # failures are handled # # Does this by using advisory locks controlling progress of # insertions. By waiting when building the index keys, it's possible # to schedule concurrent INSERT ON CONFLICTs so that there will always # be a speculative conflict. setup { CREATE OR REPLACE FUNCTION blurt_and_lock_123(text) RETURNS text IMMUTABLE LANGUAGE plpgsql AS $$ BEGIN RAISE NOTICE 'blurt_and_lock_123() called for % in session %', $1, current_setting('spec.session')::int; -- depending on lock state, wait for lock 2 or 3 IF pg_try_advisory_xact_lock(current_setting('spec.session')::int, 1) THEN RAISE NOTICE 'acquiring advisory lock on 2'; PERFORM pg_advisory_xact_lock(current_setting('spec.session')::int, 2); ELSE RAISE NOTICE 'acquiring advisory lock on 3'; PERFORM pg_advisory_xact_lock(current_setting('spec.session')::int, 3); END IF; RETURN $1; END;$$; CREATE OR REPLACE FUNCTION blurt_and_lock_4(text) RETURNS text IMMUTABLE LANGUAGE plpgsql AS $$ BEGIN RAISE NOTICE 'blurt_and_lock_4() called for % in session %', $1, current_setting('spec.session')::int; RAISE NOTICE 'acquiring advisory lock on 4'; PERFORM pg_advisory_xact_lock(current_setting('spec.session')::int, 4); RETURN $1; END;$$; CREATE OR REPLACE FUNCTION ctoast_large_val() RETURNS TEXT LANGUAGE SQL AS 'select array_agg(md5(g::text))::text from generate_series(1, 256) g'; CREATE TABLE upserttest(key text, data text); CREATE UNIQUE INDEX upserttest_key_uniq_idx ON upserttest((blurt_and_lock_123(key))); } teardown { DROP TABLE upserttest; } session controller setup { SET default_transaction_isolation = 'read committed'; } step controller_locks {SELECT pg_advisory_lock(sess, lock), sess, lock FROM generate_series(1, 2) a(sess), generate_series(1,3) b(lock);} step controller_unlock_1_1 { SELECT pg_advisory_unlock(1, 1); } step controller_unlock_2_1 { SELECT pg_advisory_unlock(2, 1); } step controller_unlock_1_2 { SELECT pg_advisory_unlock(1, 2); } step controller_unlock_2_2 { SELECT pg_advisory_unlock(2, 2); } step controller_unlock_1_3 { SELECT pg_advisory_unlock(1, 3); } step controller_unlock_2_3 { SELECT pg_advisory_unlock(2, 3); } step controller_lock_2_4 { SELECT pg_advisory_lock(2, 4); } step controller_unlock_2_4 { SELECT pg_advisory_unlock(2, 4); } step controller_show {SELECT * FROM upserttest; } step controller_show_count {SELECT COUNT(*) FROM upserttest; } step controller_print_speculative_locks { SELECT pa.application_name, locktype, mode, granted FROM pg_locks pl JOIN pg_stat_activity pa USING (pid) WHERE locktype IN ('spectoken', 'transactionid') AND pa.datname = current_database() AND pa.application_name LIKE 'isolation/insert-conflict-specconflict/s%' ORDER BY 1, 2, 3, 4; } session s1 setup { SET default_transaction_isolation = 'read committed'; SET spec.session = 1; } step s1_begin { BEGIN; } step s1_create_non_unique_index { CREATE INDEX upserttest_key_idx ON upserttest((blurt_and_lock_4(key))); } step s1_confirm_index_order { SELECT 'upserttest_key_uniq_idx'::regclass::int8 < 'upserttest_key_idx'::regclass::int8; } step s1_upsert { INSERT INTO upserttest(key, data) VALUES('k1', 'inserted s1') ON CONFLICT (blurt_and_lock_123(key)) DO UPDATE SET data = upserttest.data || ' with conflict update s1'; } step s1_insert_toast { INSERT INTO upserttest VALUES('k2', ctoast_large_val()) ON CONFLICT DO NOTHING; } step s1_commit { COMMIT; } step s1_noop { } session s2 setup { SET default_transaction_isolation = 'read committed'; SET spec.session = 2; } step s2_begin { BEGIN; } step s2_upsert { INSERT INTO upserttest(key, data) VALUES('k1', 'inserted s2') ON CONFLICT (blurt_and_lock_123(key)) DO UPDATE SET data = upserttest.data || ' with conflict update s2'; } step s2_insert_toast { INSERT INTO upserttest VALUES('k2', ctoast_large_val()) ON CONFLICT DO NOTHING; } step s2_commit { COMMIT; } step s2_noop { } # Test that speculative locks are correctly acquired and released, s2 # inserts, s1 updates. permutation # acquire a number of locks, to control execution flow - the # blurt_and_lock_123 function acquires advisory locks that allow us to # continue after a) the optimistic conflict probe b) after the # insertion of the speculative tuple. controller_locks controller_show s1_upsert s2_upsert controller_show # Switch both sessions to wait on the other lock next time (the speculative insertion) controller_unlock_1_1 controller_unlock_2_1 # Allow both sessions to continue controller_unlock_1_3 controller_unlock_2_3 controller_show # Allow the second session to finish insertion controller_unlock_2_2 # This should now show a successful insertion controller_show # Allow the first session to finish insertion controller_unlock_1_2 # This should now show a successful UPSERT controller_show # Test that speculative locks are correctly acquired and released, s1 # inserts, s2 updates. permutation # acquire a number of locks, to control execution flow - the # blurt_and_lock_123 function acquires advisory locks that allow us to # continue after a) the optimistic conflict probe b) after the # insertion of the speculative tuple. controller_locks controller_show s1_upsert s2_upsert controller_show # Switch both sessions to wait on the other lock next time (the speculative insertion) controller_unlock_1_1 controller_unlock_2_1 # Allow both sessions to continue controller_unlock_1_3 controller_unlock_2_3 controller_show # Allow the first session to finish insertion controller_unlock_1_2 # This should now show a successful insertion controller_show # Allow the second session to finish insertion controller_unlock_2_2 # This should now show a successful UPSERT controller_show # Test that speculatively inserted toast rows do not cause conflicts. # s1 inserts successfully, s2 does not. permutation # acquire a number of locks, to control execution flow - the # blurt_and_lock_123 function acquires advisory locks that allow us to # continue after a) the optimistic conflict probe b) after the # insertion of the speculative tuple. controller_locks controller_show s1_insert_toast s2_insert_toast controller_show # Switch both sessions to wait on the other lock next time (the speculative insertion) controller_unlock_1_1 controller_unlock_2_1 # Allow both sessions to continue controller_unlock_1_3 controller_unlock_2_3 controller_show # Allow the first session to finish insertion controller_unlock_1_2 # This should now show that 1 additional tuple was inserted successfully controller_show_count # Allow the second session to finish insertion and kill the speculatively inserted tuple controller_unlock_2_2 # This should show the same number of tuples as before s2 inserted controller_show_count # Test that speculative locks are correctly acquired and released, s2 # inserts, s1 updates. With the added complication that transactions # don't immediately commit. permutation # acquire a number of locks, to control execution flow - the # blurt_and_lock_123 function acquires advisory locks that allow us to # continue after a) the optimistic conflict probe b) after the # insertion of the speculative tuple. controller_locks controller_show s1_begin s2_begin s1_upsert s2_upsert controller_show # Switch both sessions to wait on the other lock next time (the speculative insertion) controller_unlock_1_1 controller_unlock_2_1 # Allow both sessions to continue controller_unlock_1_3 controller_unlock_2_3 controller_show # Allow the first session to finish insertion controller_unlock_1_2 # But the change isn't visible yet, nor should the second session continue controller_show # Allow the second session to finish insertion, but it's blocked controller_unlock_2_2 controller_show # But committing should unblock s1_commit controller_show s2_commit controller_show # Test that speculative wait is performed if a session sees a speculatively # inserted tuple. A speculatively inserted tuple is one which has been inserted # both into the table and the unique index but has yet to *complete* the # speculative insertion permutation # acquire a number of advisory locks to control execution flow - the # blurt_and_lock_123 function acquires advisory locks that allow us to # continue after a) the optimistic conflict probe and b) after the # insertion of the speculative tuple. # blurt_and_lock_4 acquires an advisory lock which allows us to pause # execution c) before completing the speculative insertion # create the second index here to avoid affecting the other # permutations. s1_create_non_unique_index # confirm that the insertion into the unique index will happen first s1_confirm_index_order controller_locks controller_show s2_begin # Both sessions wait on advisory locks # (but don't show s2_upsert as complete till we've seen all of s1's notices) s1_upsert s2_upsert (s1_upsert notices 10) controller_show # Switch both sessions to wait on the other lock next time (the speculative insertion) controller_unlock_1_1 controller_unlock_2_1 # Allow both sessions to do the optimistic conflict probe and do the # speculative insertion into the table # They will then be waiting on another advisory lock when they attempt to # update the index controller_unlock_1_3 controller_unlock_2_3 controller_show # take lock to block second session after inserting in unique index but # before completing the speculative insert controller_lock_2_4 # Allow the second session to move forward controller_unlock_2_2 # This should still not show a successful insertion controller_show # Allow the first session to continue, it should perform speculative wait controller_unlock_1_2 # Should report s1 is waiting on speculative lock controller_print_speculative_locks # Allow s2 to insert into the non-unique index and complete. s1 will # no longer wait on speculative lock, but proceed to wait on the # transaction to finish. The no-op step is needed to ensure that # we don't advance to the reporting step until s2_upsert has completed. controller_unlock_2_4 s2_noop # Should report that s1 is now waiting for s2 to commit controller_print_speculative_locks # Once s2 commits, s1 is finally free to continue to update s2_commit s1_noop # This should now show a successful UPSERT controller_show # Ensure no unexpected locks survive controller_print_speculative_locks