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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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