MSetIterator::get_percent Shows Increased Values When Using Query::OP_FILTER

[Michael Henson]

I'm seeing some rather odd behavior with respect to the match percent that is returned when performing a simple query. It appears that the addition of a filter to a simple OR query will not affect the weight of the match, but will increase the percent of the resulting match. According to the documentation for MSetIterator::get_percent (​http://xapian.org/docs/apidoc/html/classXapian_1_1MSetIterator.html#99514c11a9291175d20fafa73a0839fd) a match should only get 100% if it matches all of the weight contributing terms in the query.

I've attached a test case that shows the odd behavior that I am seeing. I had a database with 2 documents, each with one term 'cold' and 'kid'. Each document also has a boolean term for the owner of the document 'Ome'.

Below are the results for a search for 'cold kids' on that set with and without the owner filter. The weight 0.405465108108 stays the same for both queries, but the percentage increases from 50 to 100 with the addition of the filter.

Query: Xapian::Query((cold OR kids))
1 - 0.405465108108 - 50 - Ome, cold
2 - 0.405465108108 - 50 - Ome, kids

Query: Xapian::Query(((cold OR kids) FILTER Ome))
1 - 0.405465108108 - 100 - Ome, cold
2 - 0.405465108108 - 100 - Ome, kids

[Michael Henson]

Test Case Illustrating the Bug

[Olly Betts]

Candidate fix

[Olly Betts]

The attached patch fixes your testcase for me on trunk. I'll apply it once I've got a testcase for the testsuite.

1.2.x probably has the same issue, so this probably wants backporting. What version are you seeing this with?

[Olly Betts]

Fixed in trunk by r16429. The testcase I added fails with 1.2, so I guess this fix needs backporting.

[Olly Betts]

Backported for 1.2.10 in r16449.