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