New Account Types and data equivalency (was post TB 3.1 mailnews backend plans)

Andrew Sutherland asutherland at asutherland.org
Mon Jul 19 21:00:42 UTC 2010


  On 07/19/2010 12:23 PM, Robert Kaiser wrote:
> Anything that can't be recreated from other data we have stored. If we 
> start doing that, we break the assumption that was laid on gloda until 
> this day, esp. if it means that other things than search stop working 
> with gloda disabled. And I'm not a friend of that, as IMHO that would 
> mean us basically creating another equivalent of the Outlook .pst 
> format, which is the largest failure in any messaging app I ever saw 
> and one of the worst data formats I ever have heard of as it doesn't 
> allow separation of data belonging to different things.

I think you may be making some assumptions about the implementation and 
design decisions that are not consistent with my plans.  It's also worth 
noting that even if we were to store all authoritative data exclusively 
in SQLite with no export support, the SQLite database format is well 
documented ( http://www.sqlite.org/fileformat.html ), the source is in 
the public domain and it compiles on basically every platform 
available.  We would have to go really far out of our way to create an 
equivalent of the pst situation back in the day.

My primary concerns about storing authoritative data are avoiding data 
corruption and standardized export.

SQLite does everything in its power to avoid data corruption.  The 
unfortunate reality of the situation is that not all file systems and 
storage hardware actually make it possible for SQLite to achieve its 
aims ( http://www.sqlite.org/draft/lockingv3.html#ext3-barrier-problem 
).  When betrayed by lower levels in the stack, a page-oriented SQLite 
database is much more likely to end up in a bad way than append-only 
file formats or storage distributed over many orthogonal files.  This 
will be kept in mind.

Export is a trickier problem.  While we can always serve up data as it 
was first served to us, additional user-created meta-data may not map 
into that format at all or in a standard fashion.  For example, 
Thunderbird e-mail tags may or may not be persisted into the mbox 
storage as a custom header line.  While other software may understand 
how to interpret this header line, it is not remotely a standard.

Andrew
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