Hi Marc,
4.1.0 is no worse in this regard than 4.0.x, however given that the performance issues appeared to be the primary reason for the dropping of 5.1 in 4.1 (at least that was the implications from postings in the discussions of the show databases command and disableIS issues), I thought it important to express that, not just so the underlying issue can be resolved for MySQL versions 5.5 and above, but also because a number of distros still ship MySQL 5.1 as its default version, as do multiple shared hosting providers and that keeping 5.1 support would probably benefit a reasonable percentage of your userbase.
Unfortunately due to time constraints, offering a fully working solution is not something I am able to do at present, however I can provide my (admittedly horrifically hacky) solution that solves the most severe issue experienced.
I added code to getData (libraries/navigation/Nodes/Node.class.php) which is provided at the close of this message. The purpose of this was to simply return a query object that contained the static information based on the only_db contents. This way, the related node building functions did not also need to be edited. For the start of a more complete solution, I would add a check in there to make sure only_db is actually set before building it, otherwise having it fall back over to the non database code, as the code provided will fail if only_db is not set.
The only downside to this base approach is that if an only_db database does not exist, it will still display on the navigation (whereas currently it would not), however its children of course wont as they still use the classic checks. It might however be an opportunity to display that fact, so users who use only_db are informed they have non existent databases in their list.
Following is probably some of the most horrible code to hit the mailing list, but hopefully it gives someone who is more familiar with the PMA codebase an idea. I shall also keep an eye on the mailing list in case I get the time to offer something a little more substantial.
if ($type == 'databases')
{
$db_list = $GLOBALS['cfg']['Server']['only_db'];
$query = "SELECT * FROM ( SELECT '";
if (is_string($db_list))
{
$db_list = array($db_list);
}
if (count($db_list))
{
$query .= implode("' UNION ALL SELECT '",$db_list);
$query .= "' ";
}
return $GLOBALS['dbi']->fetchResult($query . ") as alias");
}
else
{
// ORIGINAL getData CODE
}