[Mediawiki-l] Search fails after MediaWiki 1.9.2 -> 1.16.0 upgrade

[Brion Vibber]

On Mon, Nov 15, 2010 at 1:10 PM, <roger at rogerchrisman.com> wrote:

> Two weeks ago I upgraded my wiki, http://wikigogy.org, from MediaWiki
> 1.9.2 to 1.16.0.
>
> Maintenance/update.php ran fine (after I removed the leading './' from
> the path to Bad Behavior in LocalSettings.php which had thrown a
> warning the first time through).
>
> I now see that _search_ is not finding all pages it should: I _think_
> search is finding only pages that have been edited post upgrade!
>

The word "and" is a) less than 4 letters and thus excluded from MySQL's
default fulltext indexing, and b) on a blacklist of "common words" causing
it to also be not indexed if you previously had adjusted your minimum word
length settings.

In MediaWiki 1.13 and earlier, we passed those words straight through to
MySQL, and the things it disappeared for us would just plain vanish. In
MediaWiki 1.14 and later, we pad words that would have been too short to end
up in the index; this can also work around the ignore blacklist.

Long story short -- the 1.16 system tries to do a query with a padded
version of the word "and", which isn't found in the old indexed entries from
1.9, so the old pages don't show up.

I've reopened https://bugzilla.wikimedia.org/show_bug.cgi?id=17733 which
refers to this sort of phenomenon.

The good news is you can clear it up easily by reindexing everything;
maintenance/rebuildtextindex.php should do the job for you.

-- brion