[WebStorage] Concerns on spec section 'Processing Model'

[Adding the subject, sorry for spam!]

Hey folks,

                I have few questions on Web Storage Spec.  I have checked the content of both latest published spec<http://www.w3.org/TR/webstorage/> and  latest editors spec<http://dev.w3.org/html5/webstorage/>.  And the questions are applicable to both the versions of the spec.

                Section: 4.4.2 Processing model
                Text:

1.       Open a new SQL transaction to the database, and create a SQLTransaction<http://www.w3.org/TR/webstorage/#sqltransaction> object that represents that transaction. If the mode is read/write, the transaction must have an exclusive write lock over the entire database. If the mode is read-only, the transaction must have a shared read lock over the entire database. The user agent should wait for an appropriate lock to be available.


Concerns:

-          Why is the spec mandating a transaction to take an *exclusive write lock on the entire database*?  No database book design mandates it.  In fact, many client databases out there don't do this.  I guess SQLite does this kind.  But that does not mean that all implementations have this nature.  I am kind of worried that we are putting implementation in theory.  For me they are too separate, there are many ways a database could be designed.  Like, log+checkpoint approach,  shadow copy, version store, journals ...etc.  I guess spec should say what a browser should do and not how.

I would be happy to get enlightened.

Thanks,
Laxmi