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# Read-write-unique test.
# Implementing a gapless sequence of ID numbers for each year.
setup
{
CREATE TABLE invoice (
year int,
invoice_number int,
PRIMARY KEY (year, invoice_number)
);
INSERT INTO invoice VALUES (2016, 1), (2016, 2);
}
teardown
{
DROP TABLE invoice;
}
session "s1"
setup { BEGIN ISOLATION LEVEL SERIALIZABLE; }
step "r1" { SELECT COALESCE(MAX(invoice_number) + 1, 1) FROM invoice WHERE year = 2016; }
step "w1" { INSERT INTO invoice VALUES (2016, 3); }
step "c1" { COMMIT; }
session "s2"
setup { BEGIN ISOLATION LEVEL SERIALIZABLE; }
step "r2" { SELECT COALESCE(MAX(invoice_number) + 1, 1) FROM invoice WHERE year = 2016; }
step "w2" { INSERT INTO invoice VALUES (2016, 3); }
step "c2" { COMMIT; }
# if they both read first then there should be an SSI conflict
permutation "r1" "r2" "w1" "w2" "c1" "c2"
# cases where one session doesn't explicitly read before writing:
# if s2 doesn't explicitly read, then trying to insert the value
# generates a unique constraint violation after s1 commits, as if s2
# ran after s1
permutation "r1" "w1" "w2" "c1" "c2"
# if s1 doesn't explicitly read, but s2 does, then s1 inserts and
# commits first, should s2 experience an SSI failure instead of a
# unique constraint violation? there is no serial order of operations
# (s1, s2) or (s2, s1) where s1 succeeds, and s2 doesn't see the row
# in an explicit select but then fails to insert due to unique
# constraint violation
permutation "r2" "w1" "w2" "c1" "c2"
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