findSimilarBugs() in the Launchpad API returns strange things

[Brian Murray]

I find the results of using findSimilarBugs() in the Launchpad API to be rather unhelpful and wish it would returned more useful results. Here are some examples of the odd results I've seen:

LP: #19885 - memtest86+: does not work: wouldn't fit into memory
 is similar to
 LP: 14639 - Unstable system (Oopses?) since 2.6.10
 LP: 520463 - grub cannot be installed on intel 82801 raid controller

LP: #614154 - Add a 'group by xxx' feature to the bugs view
 is similar to
 LP: 227960 - KTorrent (KDE 4) new upstream release
 LP: 297941 - Please backport LyX 1.6.1-1 to 8.04 and 8.10
 LP: 296433 - [jaunty] ktorrent changes in Debian require merging

LP: #774434 - mouse pointer disappears in ubuntu 11.04
 is similar to
 LP: 438970 - kdeinit4 crashed with SIGSEGV

Analysis
========

So findSimilarBugs is a thing wrapper around findSimilar using the bug title. findSimilar does a natural language search using AND between the terms in the title. This is the same search that duplicate finding does, and works by searching for permutations of the terms unioned together - see
lib/canonical/database/nl_search.py _nl_phrase_search() for the gory details.

This is currently a bit of a compromise due to the limitations of tsearch2 - can't search for a term and get a result that matches all the other terms but not that one term.