Add isolation test for SERIALIZABLE READ ONLY DEFERRABLE.

This improves code coverage and lays a foundation for testing
similar issues in a distributed environment.

Author: Thomas Munro <thomas.munro@enterprisedb.com>
Reviewed-by: Michael Paquier <michael.paquier@gmail.com>

src/test/isolation/specs/read-only-anomaly-2.spec

@@ -0,0 +1,42 @@
+# The example from the paper "A read-only transaction anomaly under snapshot
+# isolation"[1].
+#
+# Here we test that serializable snapshot isolation (SERIALIZABLE) doesn't
+# suffer from the anomaly, because s2 is aborted upon detection of a cycle.
+#
+# [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf
+
+setup
+{
+	CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL);
+	INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0);
+}
+
+teardown
+{
+	DROP TABLE bank_account;
+}
+
+session "s1"
+setup 		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s1ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s1wy"	{ UPDATE bank_account SET balance = 20 WHERE id = 'Y'; }
+step "s1c" 	{ COMMIT; }
+
+session "s2"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s2rx"	{ SELECT balance FROM bank_account WHERE id = 'X'; }
+step "s2ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s2wx"	{ UPDATE bank_account SET balance = -11 WHERE id = 'X'; }
+step "s2c"	{ COMMIT; }
+
+session "s3"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s3r"	{ SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; }
+step "s3c"	{ COMMIT; }
+
+# without s3, s1 and s2 commit
+permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s2wx" "s2c" "s3c"
+
+# once s3 observes the data committed by s1, a cycle is created and s2 aborts
+permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s3r" "s3c" "s2wx"

src/test/isolation/specs/read-only-anomaly-3.spec

@@ -0,0 +1,39 @@
+# The example from the paper "A read-only transaction anomaly under snapshot
+# isolation"[1].
+#
+# Here we test that serializable snapshot isolation can avoid the anomaly
+# without aborting any tranasctions, by instead causing s3 to be deferred
+# until a safe snapshot can be taken.
+#
+# [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf
+
+setup
+{
+	CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL);
+	INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0);
+}
+
+teardown
+{
+	DROP TABLE bank_account;
+}
+
+session "s1"
+setup 		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s1ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s1wy"	{ UPDATE bank_account SET balance = 20 WHERE id = 'Y'; }
+step "s1c" 	{ COMMIT; }
+
+session "s2"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; }
+step "s2rx"	{ SELECT balance FROM bank_account WHERE id = 'X'; }
+step "s2ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s2wx"	{ UPDATE bank_account SET balance = -11 WHERE id = 'X'; }
+step "s2c"	{ COMMIT; }
+
+session "s3"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE READ ONLY DEFERRABLE; }
+step "s3r"	{ SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; }
+step "s3c"	{ COMMIT; }
+
+permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s3r" "s2wx" "s2c" "s3c"

src/test/isolation/specs/read-only-anomaly.spec

@@ -0,0 +1,38 @@
+# The example from the paper "A read-only transaction anomaly under snapshot
+# isolation"[1].
+#
+# Here we use snapshot isolation (REPEATABLE READ), so that s3 sees a state of
+# afairs that is not consistent with any serial ordering of s1 and s2.
+#
+# [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf
+
+setup
+{
+	CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL);
+	INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0);
+}
+
+teardown
+{
+	DROP TABLE bank_account;
+}
+
+session "s1"
+setup 		{ BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; }
+step "s1ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s1wy"	{ UPDATE bank_account SET balance = 20 WHERE id = 'Y'; }
+step "s1c" 	{ COMMIT; }
+
+session "s2"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; }
+step "s2rx"	{ SELECT balance FROM bank_account WHERE id = 'X'; }
+step "s2ry"	{ SELECT balance FROM bank_account WHERE id = 'Y'; }
+step "s2wx"	{ UPDATE bank_account SET balance = -11 WHERE id = 'X'; }
+step "s2c"	{ COMMIT; }
+
+session "s3"
+setup		{ BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; }
+step "s3r"	{ SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; }
+step "s3c"	{ COMMIT; }
+
+permutation "s2rx" "s2ry" "s1ry" "s1wy" "s1c" "s3r" "s2wx" "s2c" "s3c"