Nominatim/Version2

From OpenStreetMap Wiki
Jump to: navigation, search

Changes

Indexing

  • Merge admin boundaries and place nodes (where within 2 levels of rank)
  • Modify Voronoi algorithm to take account of known fixed boundaries
  • Native postgresql Voronoi
  • Additional per-country index to speed up searches within country - might require better county polygons in OSM?
  • Various problems with German postfixes / abbreviations
  • Performance - indexing is far too slow. Test clustering and polygon generation to see effects
  • Move to hstore for name storage for compatibility
  • Import minute change sets so index fully up to date
  • (TODO) Assign UUID to features. Ideally UUID should be consistent between nominatim systems! (is that even possible?!?)
  • (TODO) Generate indexes in memory

Search

  • (TODO) Re-write search logic in java.
  • Use statistics to estimate phrase importance to improve ordering of search graph
  • Change all scoring functions to a 0 to 1 scale so scores can be calculated using multiple factors
  • Re-score strings after index search (index is lossy, we should recheck - perfect matches should beat transliterations)
  • (TODO) Options for fallback to high level feature when low level features missing (i.e. town when street not yet present)
  • (TODO) 'Did you means' Suggestions. Can't use standard - too many words and phrases (too slow) - so:
    • High level admin features only?
    • Modified levenshtein btree?
    • Geographic indexing of suggestions?
    • Word context based indexing?
  • Allow detailed / structured search terms in query (i.e. country=DE&city=Berlin)
  • (partially done) Search for amenities by tag pair
  • Search graph to take account of in / nearest rather than just dropping them (partially done)
  • Multilingual support for nearest / in / im (possible list of words in wiki (Name_finder:Translations)
  • (TODO) Searching for street intersections
  • (FAILED) Provide option to use postgresql full text search module as alternative indexing method
  • (TODO) Better formatting of address output (address format def on wiki? crowdsource?)
  • (TODO) Indexing support for autocomplete text entry (prefix search)

Code

(TODO) Re-factor and reorganise the code - its a bit of a mess!

Gazetteer Output

  • Minor index change required to make this efficient, but requires complete re-index of planet
  • xml interface
  • Visual representation of address 'graph' to help people debug

Export

  • (TODO) Provide export files (xml?) at various detail levels
    • Structured? (in progress)
    • Flat?
  • (TODO) Provide postgresql dump file to get people started?