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From Christiaan <christiaan...@hotmail.com>
Subject Re: Query closures for JDO 2.2
Date Tue, 11 Dec 2007 20:43:19 GMT

since you are calling this "perform" would there also be a possibility to
somehow incorporate my copy by query feature request? 

As a side and practical note, I am working in a domain where many objects
are involved, so for performance and memory issues it would really benefit
from these "bulk" operations. The delete-by-query was a real must have in
that regard. However, in the field I am working, I doubt whether
update-by-query would be of the same added value for two reasons:
1) updating in our domain often involves some complex logic, eg. values
should be updated based on values in other (children) objects and other
factors. Could this be expressed in the closure? (and if it is, wouldn't
that be too much going against the OO paradigm)
2) our experience is that these update operations can be done really quick
within reasonable memory usage due to fetchgroups (you only load what you
need) and fetchsize (having the right value really speeds up iterating). 

On the other hand, as mentioned in the copy-by-query request, copying can be
a very time and memory consuming task, since both original and copy need to
be completely in memory, while most of the time there is no need to load
them into memory.

kind regards,

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