Re: db Model and EOModel
Re: db Model and EOModel
- Subject: Re: db Model and EOModel
- From: Art Isbell <email@hidden>
- Date: Sat, 22 Mar 2008 12:30:42 -1000
On Mar 22, 2008, at 4:07 AM, James Cicenia wrote:
But is there a rule of thumb about which attributes should have it
turned on, and, why when you create an attribute it is always on?
You shouldn't use any attribute for locking that may not match in a
where clause only due to rounding, truncating, or other differences in
precision between the DB and the WO app. Floats, doubles, etc., would
be in that category. For some databases, dates would also be in that
category, particularly when the date has a precision in fractional
seconds. All of these could result in false optimistic locking errors.
If you don't care whether user1 could update an attribute that might
have been updated by user2 since user1 fetched the object whose
attribute is being updated (i.e., user1 would be updating an attribute
whose current value he hadn't seen), then this attribute need to be
used for locking.
I guess the default is for an attribute to be used for locking
because it's probably more common that a user should not be allowed to
update an attribute whose value had changed without his knowledge.
Aloha,
Art
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