[DERBY-3185] SET (TRANSACTION) ISOLATION (LEVEL) is not SQL compliant

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 10.3.1.4
• Component/s: JDBC, SQL
• Labels: derby_triage10_8
• Urgency: Low
• Assignee: Unassigned
• Reporter: Dyre Tjeldvoll
• Created: 07/Nov/07 14:12
• Updated: 16/Feb/11 14:39

Description

The SQL standard (2003) requires the keyword 'TRANSACTION' and allows the keyword 'LEVEL' in
SET TRANSACTION ISOLATION LEVEL <level> Derby permits neither and issues a syntax error (but permits the optional word 'CURRENT').

There is also an inconsistency between JDBC and SQL when specifying 'repeatable read' isolation level.

Specifying repeatable read from JDBC works as expected:
conn.setTransactionIsolation(Connection.TRANSACTION_REPEATABLE_READ);
assert(conn.getTransactionIsolation() == Connection.TRANSACTION_REPEATABLE_READ) // OK

Doing it in SQL yields RR or
SET ISOLATION REPEATABLE READ;
VALUES CURRENT ISOLATION; -> RR
assert(conn.getTransactionIsolation() == Connection.TRANSACTION_REPEATABLE_READ) // FAILS, RR is translated into Connection.TRANSACTION_SERIALIZABLE

Using RS in SQL works as expected
SET ISOLATION RS;
VALUES CURRENT ISOLATION; -> RS
assert(conn.getTransactionIsolation() == Connection.TRANSACTION_REPEATABLE_READ) // OK

I guess there could be backward compatibility issues that makes it difficult to change this,
but the current behavior is really confusing and should at least be better documented. An alternative is to add a new
SQL compliant SET TRANSACTION which uses the standard isolation level specifiers, and keep SET (CURRENT) ISOLATION as it is today for backward
compatibility.