#2227: transaction.commit()/rollback() should be aware of nested calls to
transaction.managed(True)
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Reporter: mderk@… | Owner: nobody
Type: New | Status: assigned
feature | Component: Database layer
Milestone: | (models, ORM)
Version: SVN | Severity: Normal
Resolution: | Keywords: transaction, nest,
Triage Stage: Accepted | scope, nested, rollback, commit
Needs documentation: 0 | Has patch: 1
Patch needs improvement: 1 | Needs tests: 0
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Changes (by etianen):
* cc: etianen (added)
Comment:
I agree that nested calls to transaction management commands should
transparent start using savepoints. It seems like the obvious abstraction
layer.
However, for backends which do not support savepoints, what would the
fallback be? The only thing I can think of is to check for nesting and
only allow transactions to commit in the outer nested block. This means
that different backends will behave very differently, massively breaking
the abstraction.
For backwards compatibility, the current transaction handling methods will
probably have to stay, as they provide a 'broken', yet consistent way of
handling transactions between backends. There are workarounds for core
framework features, such as #15694. However, a new set of decorators with
a slightly different API could be provided in parallel, with a signature
something like this:
{{{
@transaction.commit_block(savepoint=False)
def do_something(request):
# Do something...
}}}
This decorator (with a better name), would work like commit_on_success,
but only actually perform the commit when the outer block exits. The
optional savepoint=True parameter would provide more fine-grained rollback
support using savepoints, but generate a warning on backends which do not
support savepoints. The core framework could use this on things like the
admin views, but would avoid using the savepoint support (this is for
individual projects to decide).
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Ticket URL: <http://code.djangoproject.com/ticket/2227#comment:27>
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