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# Write skew test.
#
# This test has two serializable transactions: one which updates all
# 'apple' rows to 'pear' and one which updates all 'pear' rows to
# 'apple'. If these were serialized (run one at a time) either
# value could be present, but not both. One must be rolled back to
# prevent the write skew anomaly.
#
# Any overlap between the transactions must cause a serialization failure.
setup
{
CREATE TABLE test (i int PRIMARY KEY, t text);
INSERT INTO test VALUES (5, 'apple'), (7, 'pear'), (11, 'banana');
}
teardown
{
DROP TABLE test;
}
session "s1"
setup { BEGIN ISOLATION LEVEL SERIALIZABLE; }
step "rwx1" { UPDATE test SET t = 'apple' WHERE t = 'pear'; }
step "c1" { COMMIT; }
session "s2"
setup { BEGIN ISOLATION LEVEL SERIALIZABLE; }
step "rwx2" { UPDATE test SET t = 'pear' WHERE t = 'apple'}
step "c2" { COMMIT; }
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