[whatwg] Private browsing vs. Storage and Databases

[Scott Hess]

On Tue, Apr 7, 2009 at 6:33 PM, Brady Eidson <beidson at apple.com> wrote:
> On Apr 7, 2009, at 6:24 PM, Jeremy Orlow wrote:
>> Both would lead to bizarre behavior where data that the application
>> thought was saved really wasn't.
>>
>> This matches up with how most private browsing sessions handle cookies,
>> right?  The data persists until the session is up (because some of the web
>> can't work correctly without them) but then they're deleted at the end.
>
> I guess I'll raise this point yet again, as it's a favorite of mine...  ;)
>  Cookies are not expected to be persistent, and when space runs out for them
> and they're expired there is already no notification of that.  Any app
> writer that expected cookies to be a safe, persistent store of data or state
> was already playing with fire.

As I periodically learn to my continued dismay, the database hasn't
been invented which can surmount obstacles such as broken hardware and
systems which report success optimistically (as when fsync doesn't
really mean bits on the disk).  Any app running at scale WILL see
missing databases, and surprisingly frequently.    I think that saying
that databases and cookies have the same expected persistence
characteristics is a reasonable first approximation.

-scott