When ParadeDB is in use and a search is run, results now keep the current
fuzzy/OR matching but are ordered by BM25 relevance so tasks matching all
query words rank above tasks matching only some.
Details:
- ParadeDB exposes the BM25 score via pdb.score(<key_field>); Vikunja's
key_field is id, so we order by pdb.score(tasks.id) DESC, then the
existing order-by (ending in a stable tasks.id tiebreak).
- Gating: relevance ordering only applies when ParadeDB is available, a
search term is present, AND the user did not pass an explicit sort_by.
An explicit user sort still wins; relevance only replaces the default
(id / position) sort.
- DISTINCT requires every ORDER BY expression to appear in the SELECT
list, so pdb.score(tasks.id) is added to the selected columns too (for
both the plain and task_positions-join query shapes). Because xorm's
Distinct() quotes each column and corrupts the function call, the
ranking path uses Select(rawColumns).Distinct() instead.
- ParadeDB-only by nature: pdb.score is invalid SQL on sqlite, mysql and
plain postgres, so those paths are completely unchanged.
A test (TestTaskSearchRelevanceRanking) creates a task matching all query
words plus tasks matching only one, then searches a multi-word query. On
ParadeDB it asserts the all-words task ranks first; on other databases it
only asserts the matching tasks are returned, so it stays green across the
whole CI database matrix. The CI ParadeDB matrix entry exercises the
ranking assertion.
Follow-up (not in this change): boosting results where the words appear in
order / in close proximity above plain all-words matches.
Fixes#2690
9fb0d86c1b