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From Daniel John Debrunner <...@apache.org>
Subject Re: [jira] Commented: (DERBY-690) Add scrollable, updatable, insensitive result sets
Date Thu, 23 Feb 2006 17:04:44 GMT
Fernanda Pizzorno (JIRA) wrote:

> Read-uncommited isolation level does aquire locks for updatable forward-only result sets,
the same behavior has been kept on scrollable insensitve updatable result sets.

Hmmm, this means such ResultSets are not running at read-uncommitted
isolation level, they are running at read-committed isolation level.

I understand this is existing behaviour, I wonder if it arises due to
SELECT's FOR UPDATE causing this locking behaviour.

Customers in the past have complained about any locks obtained in
read-uncommitted mode, it might be suprising for them to have a
read-uncommitted ResultSet blocked by other transactions.

I wonder if, at least for scrollable updateable ResultSets, we should
disallow read-uncommitted isolation level, it may be a cleaner way
forward thean implementing them as read-committed and then have concerns
in the future about backwards compatibility if we ever need to implement
them correctly. Maybe the more precise statement is disallow updateRow
and deleteRow when the isolation level is read un-committed. insertRow
seems fine.

Forward-only updateable read-uncommitted ResultSets ideally should be
disallowed as well, but that might cause backward compatibility issues.


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