[Refdb-devel] xnote links

Discussion:

Damien Jade Duff

2006-07-20 09:14:07 UTC

Hello hello

The current svn version appears to
work ok with the data and the procedure that you described.

Thanks Markus, cool - I can't get svn to work across my network and I'm
a bit lazy so I'll wait for the next pre-release. No rush.

Incidentally, what are the chances of getting note-note links working so

(afait it boils down to allowing an additional type string in one of
the fields).

I think I know what you mean - you'd allow presumably a NOTE string in
the xnote_type field of the t_xnote table. Though I think that would
only allow for unidirectional links unless you were happy to let your
backend try to keep two links updated (I believe this is sort of frowned
upon in the relational DB world) or to search two indices, note_id and
xref_id for a particular note_id (maybe okay but seems clumsy).

I could handle non-directional links outside of RefDB by automatically
generating dummy references to group notes with but it's kind of messy,
particularly as there's no real reason to group notes in groups bigger
than 2 (since you could then group notes by linking them all to another,
group note, anyway).

On the other hand, while non-directional links would be nice,
unidirectional links would be just fine as far as I'm concerned. It
would be up to the DB user to specify if he/she wanted a link going both
ways.

As far as a GUI tree view on the data is concerned, well it may recurse
sometimes, but that's just a consequence of choosing a tree to view a
potentially cyclic directed (or undirected) graph.

Feel free to talk me out of it!

Peace
Damien

Markus Hoenicka

2006-07-20 19:46:25 UTC

Permalink

Hi Damien,

probably I'm a bit dense here, but I think that links via the t_xnote
table are bidirectional by nature. It is just a matter of the proper
query. We've got the same issue with the t_refdb, t_author, and
t_xauthor tables. I can start with a name and find all
references in t_refdb that use that name as an author. I can also
start with a reference ID and retrieve all authors of this
reference. Speaking in terms of extended notes, "links to" and "is
linked from" should be pretty much the same story. Or am I missing
something here?

regards,
Markus

Post by Damien Jade Duff
I think I know what you mean - you'd allow presumably a NOTE string in
the xnote_type field of the t_xnote table. Though I think that would
only allow for unidirectional links unless you were happy to let your
backend try to keep two links updated (I believe this is sort of frowned
upon in the relational DB world) or to search two indices, note_id and
xref_id for a particular note_id (maybe okay but seems clumsy).
I could handle non-directional links outside of RefDB by automatically
generating dummy references to group notes with but it's kind of messy,
particularly as there's no real reason to group notes in groups bigger
than 2 (since you could then group notes by linking them all to another,
group note, anyway).
On the other hand, while non-directional links would be nice,
unidirectional links would be just fine as far as I'm concerned. It
would be up to the DB user to specify if he/she wanted a link going both
ways.
As far as a GUI tree view on the data is concerned, well it may recurse
sometimes, but that's just a consequence of choosing a tree to view a
potentially cyclic directed (or undirected) graph.
Feel free to talk me out of it!
Peace
Damien
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Damien Jade Duff

2006-08-16 11:38:44 UTC

Permalink

Gidday gidday

Sorry if I'm a bit obscure. I'll try and clarify what I meant.

By non-directional links (at a user interface level) I meant only that
if I link note A to note B then note B would automatically be linked to
note A.
A directional link would be that if I link note A to note B then when I
query note B I don't get back any reference to note A.

At an implemention level non-directionality means that rather than
having note A "link to" note B and, conversely, having note B "linked
from" note A, you would have note A "link to and linked from" note B.
This would involve an extra table.

Now, you can have non-directional links at a user interface level but
not at the implementation level. If this was the approach, you would
need two distinct query processes, finding all those notes linking to
your current note and finding all the notes linked from your current
note, and then exclude any duplicates. Which is fine, if you're okay
with a bit of potential duplication in your DB and/or manual constraint
enforcement. I guess I'm just being a pedantic relational purist here
(wherein the relational DB enforces this kind of constraint rather than
the app).

It also depends on what behaviour we want - I really don't care which we
get at the user level and it only seems that directional links are
easier to implement without adding in, either extra database redundancy
management code as discussed in the previous paragraph, or a new table.

Anyway, I shouldn't argue with you on the implementation details! I'm
just happy that you're considering putting the feature in!

Peace
Damien

Post by Markus Hoenicka
Hi Damien,
probably I'm a bit dense here, but I think that links via the t_xnote
table are bidirectional by nature. It is just a matter of the proper
query. We've got the same issue with the t_refdb, t_author, and
t_xauthor tables. I can start with a name and find all
references in t_refdb that use that name as an author. I can also
start with a reference ID and retrieve all authors of this
reference. Speaking in terms of extended notes, "links to" and "is
linked from" should be pretty much the same story. Or am I missing
something here?
regards,
Markus