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From "Dyre Tjeldvoll (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3185) SET (TRANSACTION) ISOLATION (LEVEL) is not SQL compliant
Date Wed, 07 Nov 2007 17:43:50 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3185?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12540813
] 

Dyre Tjeldvoll commented on DERBY-3185:
---------------------------------------

Hi AB,

No you did not misunderstand. That page explains it very well, and there is even a reference
to it in the reference guide. Perhaps I should have checked that reference, but the reference
guide also contains the following paragraph: 

"The JDBC java.sql.Connection.setTransactionIsolation method behaves almost identically to
this command, with one exception: if you are using the embedded driver, and if the call to
java.sql.Connection.setTransactionIsolation does not actually change the isolation level (that
is, if it sets the isolation level to its current value), the current transaction is not committed."


> SET (TRANSACTION) ISOLATION (LEVEL) is not SQL compliant
> --------------------------------------------------------
>
>                 Key: DERBY-3185
>                 URL: https://issues.apache.org/jira/browse/DERBY-3185
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC, SQL
>    Affects Versions: 10.3.1.4
>            Reporter: Dyre Tjeldvoll
>
> 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. 

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