[Pan-devel] Re: ancient DB schema

[Duncan]

K. Haley posted <address@hidden>, excerpted below,
 on Fri, 04 Jun 2004 18:56:11 -0600:

> GROUP
> A newsgroup.
> (it looks to me like pan treats folders the same as news groups. `folder`
> is not needed if seperate FOLDER and FOLDER_ARTICLE tables are used.)

The "looks like" statement is correct. Charles has stated that it's
deliberate that folders are treated exactly the same as groups,
simplifying the logic as there's only one set to deal with, not a separate
set for folders and for groups.

One gotcha is tracking read and unread articles.  PAN apparently uses the
server added xref line for that purpose.  Since that's a server-local
added header, a few server implementations don't add it, and folks have
from time to time complained that messages on these servers don't get
marked as read, properly.

Additionally, at one point as an performance enhancing experiment, PAN
tried not actually retrieving user-posted messages, but substituting the
local copy instead.  This failed with the same mark-as-read problem,
because the local copy didn't have the server supplied xref header. 
Additionally, it was I believe decided that it was more important to see
what actually posted, in case it got mangled or something, than the bit of
speed saved by not downloading those articles (particularly since PAN
doesn't do attachments so the articles aren't that long anyway).  I doubt
this will be tried again, but it's one example of the practical effect of
the tracking method.

Thus, however read/unread is tracked, one might wish to keep it in mind
when building the database record format, in case it changes at some
point.  Ideally it would be tracked by msg-id, making the tracking a bit
more server independent.

Another thing to consider, however, is that some servers (my own ISP's
included, as I see the complaints on the internal groups..  They are
running High Winds serverware) have bugs when retrieving by msg-id only,
so while it would be nice for PAN to have that functionality as an option,
it should not be the ONLY way PAN can retrieve.  Retrieving by xref
number, which is what I /believe/ PAN does now, should always be
supported, so it can't be eliminated entirely.

Back to folders.  It might be useful to have the ability to add old
folders back in, at some point.  I wouldn't worry about this functionality
now, except that we shouldn't break the eventual possibility by limiting
the database record format.  Basically what I'm saying, is that at some
point it would be nice to have a folder import function, that would either
read the messages and build the individual fields from them as possible,
or substitute reasonable defaults where the data cannot be gathered,
including if the message doesn't contain a "required" header.  We
shouldn't artificially limit the future ability to add this functionality,
with our formatting choices now.  (I could give practical examples if
needed but won't here, for brevity.)

Just some random thoughts.. inspired by that "looks like a group"
notation.  I'm not a db person so know not whether they pertain or not,
but would hate to find out they did only AFTER the fact.  <g>

-- 
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