[drupal-devel] forum table WTF

[Gabor Hojtsy]

>> Looking at the code and database table of the forum module, I don't
>> understand the role of the forum table to be honest. The forum  table is
>> now only a nid->tid relation, while the term_node table would  suffice to
>> express such relations. Term_node does not limit a node to only  have one
>> parent term, but that is the sole difference it seems. Some queries in
>> forum module use both the forum table and the term_node table, some  only
>> the latter.
> 
> The table might be used for the 'Leave shadow copy' feature ...  (random
> guess)?
> If we can improve the performance of the forum module, by all means.  
> It would be a tremendous improvement for sites like drupal.org, 
> spreadfirefox.com, etc.
> 
> I don't mind removing the 'Leave shadow copy' feature if it makes the 
> code simpler, improves performance and de-clutters the node edit form.
> 
> Are you going to investigate this some more?

Here are the queries where {forum} is used:

// forum_term (when a term is deleted, the results
// are run through node_delete, so forum nodes are deleted)
'SELECT f.nid FROM {forum} f WHERE f.tid = %d', $object->tid

// from forum_load
'SELECT * FROM {forum} WHERE nid = %d', $node->nid

// forum_update
'UPDATE {forum} SET tid = %d WHERE nid = %d', $node->tid, $node->nid

// forum_insert
'INSERT INTO {forum} (nid, tid) VALUES (%d, %d)', $node->nid, $node->tid

// forum_delete
'DELETE FROM {forum} WHERE nid = %d', $node->nid

// forum_get_topics:
"SELECT n.nid, f.tid, n.title, n.sticky, u.name, u.uid, n.created AS
timestamp, n.comment AS comment_mode, l.last_comment_timestamp,
IF(l.last_comment_uid, cu.name, l.last_comment_name) AS
last_comment_name, l.last_comment_uid, l.comment_count AS num_comments
FROM {node} n, {node_comment_statistics} l, {users} cu, {term_node} r,
{users} u, {forum} f WHERE n.status = 1 AND l.last_comment_uid = cu.uid
AND n.nid = l.nid AND n.nid = r.nid AND r.tid = %d AND n.uid = u.uid AND
n.nid = f.nid"

It seems that the nid->tid relationship is maintained, loaded, inserted,
updated, removed, but then only used in the forum_get_topics query and
only to ensure (on top of term_node) that the nids match. If this is
connected to the shadow copy feature, then this query is supposed to
select the 'primary term' for this particular node, and this is why the
whole maintanance stuff is needed. From the implementation of the shadow
copy feature, it stores all the relations in the term_node table, and
maintains no information on what is the primary term for a forum node.

Otherwise I see no reason to keep this table.

Goba