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RE: [IndexedDB] Passing an empty array to IDBDatabase.transaction

From: Israel Hilerio <israelh@microsoft.com>
Date: Fri, 14 Oct 2011 21:57:12 +0000
To: "Jonas Sicking (jonas@sicking.cc)" <jonas@sicking.cc>
CC: "ben turner (bent.mozilla@gmail.com)" <bent.mozilla@gmail.com>, "public-webapps@w3.org" <public-webapps@w3.org>, Tom Bolds <thombo@microsoft.com>, Adam Herchenroether <aherchen@microsoft.com>, "Victor Ngo" <vicngo@microsoft.com>
Message-ID: <F695AF7AA77CC745A271AD0F61BBC61E3F4CB926@TK5EX14MBXC117.redmond.corp.microsoft.com>
On Friday, October 14, 2011 2:43 PM, Jonas Sicking wrote:
> On Fri, Oct 14, 2011 at 2:27 PM, Israel Hilerio <israelh@microsoft.com>
> wrote:
> > On Monday, October 10, 2011 10:15 AM, Israel Hilerio wrote:
> >> On Monday, October 10, 2011 9:46 AM, Jonas Sicking wrote:
> >> > On Fri, Oct 7, 2011 at 11:51 AM, Israel Hilerio
> >> > <israelh@microsoft.com>
> >> > wrote:
> >> > > On Thursday, October 06, 2011 5:44 PM, Jonas Sicking wrote:
> >> > >> Hi All,
> >> > >>
> >> > >> In both the Firefox and the Chrome implementation you can pass
> >> > >> an empty array to IDBDatabase.transaction in order to create a
> >> > >> transaction which has a scope that covers all objectStores in
> >> > >> the database. I.e. you can do something like:
> >> > >>
> >> > >> trans = db.transaction([]);
> >> > >> trans.objectStore(<any objectstore here>);
> >> > >>
> >> > >> (Note that this is *not* a dynamic scoped transaction, it's
> >> > >> still a static scope that covers the whole database).
> >> > >>
> >> > >> In other words, these implementations treat the following two
> >> > >> lines as
> >> > >> equivalent:
> >> > >>
> >> > >> trans = db.transaction([]);
> >> > >> trans = db.transaction(db.objectStoreNames);
> >> > >>
> >> > >> This, however, is not specified behavior. According to the spec
> >> > >> as it is now the transaction should be created with an empty scope.
> >> > >>
> >> > >> I suspect both Mozilla and Google implemented it this way
> >> > >> because we had discussions about this syntax on the list.
> >> > >> However apparently this syntax never made it into the spec. I don't
> recall why.
> >> > >>
> >> > >> I'm personally not a big fan of this syntax. My concern is that
> >> > >> it makes it easier to create a widely scoped transaction which
> >> > >> has less ability to run in parallel with other transactions,
> >> > >> than to create a transaction with as narrow scope as possible.
> >> > >> And passing
> >> > db.objectStoreNames is always possible.
> >> > >>
> >> > >> What do people think we should do? Should we add this behavior
> >> > >> to the spec? Or are implementations willing to remove it?
> >> > >>
> >> > >> / Jonas
> >> > >>
> >> > >
> >> > > Our implementation interprets the empty array as an empty scope.
> >> > > We
> >> > allow the transaction to be created but we throw a NOT_FOUND_ERR
> >> > when trying to access any object stores.
> >> > > I vote for not having this behavior :-).
> >> >
> >> > Hi Israel,
> >> >
> >> > I just realized that I might have misinterpreted your response.
> >> >
> >> > Are you saying that you think that passing an empty-array should
> >> > produce a transaction with an empty scope (like in IEs
> >> > implementation and as described by the spec currently), or a
> >> > transaction with every objectStore in scope (like in Firefox and chrome)?
> >> >
> >> > / Jonas
> >> >
> >>
> >> We don't do it like FF or chrome.  We create the transaction but it
> >> has an empty scope transaction.  Therefore, whenever you try to
> >> access an object store we throw an exception.  Based on what Hans
> >> said, it seems we're all in agreement.
> >>
> >> Also, I like Ben's suggestion of not allowing these transactions to
> >> be created in the first place and throwing an exception during their
> creation.
> >>
> >> Israel
> >>
> >
> > What type of exception should we throw when trying to create a transaction
> with an empty scope (NotFoundError, TypeError, or other)?
> 
> Either of those would work for me.
> 
> / Jonas

We would like to go with NotFoundError.  The reason is that an empty array is still the correct type and therefore a TypeError would seem strange.

Israel
Received on Friday, 14 October 2011 21:57:52 GMT

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