- Overlays (aka [[ https://www.mediawiki.org/wiki/Help:Extension:Kartographer#GeoShapes_via_Wikidata_Query | GeoShapes ]]) are predefined objects on the map that are tied to latitude/longitude coordinates.
- These polygons and way objects (countries, roads, parks, etc.) are defined in OpenStreetMaps (OSM) and replicated to appear on the maps in wiki projects. (see an example below)
- Because these map overlays are defined in OpenStreetMap, they need to be synced with our infrastructure in order to display the objects and stylings in Wikimedia projects.
- There has been a substantial lag in the syncing of these 2 systems mainly due to a failure in the [[ https://www.mediawiki.org/wiki/Help:Extension:Kartographer/OSM | OSM ]] replication tool, osm2pgsql, that performs the database updates.
//[[ https://en.wikipedia.org/wiki/Central_Park#/map/0 | Map overlay of Central Park in New York City ]]//
- For the community to provide a consistent experience of map overlays for all Wikimedia projects
- For the foundation, in order to reduce the cost of maintenance for the overall maps stack
## Key Metics
| **Hypothesis** | **Metric** | **Current Benchmarks** |
| Map overlay latency reduces | [[ https://grafana.wikimedia.org/d/000000305/maps-performances?orgId=1&from=1597679211557&to=1597690011557&var-cluster=maps-test2&panelId=12&fullscreen | OSM Sync Lag ]] | < 3 days (99% of the time by EOFY) |
| Maintence effort reduces | Full-time Engineer effort on *incidents | < 10% (per quarter)
//*incidents only consider outages and do not include general maintenance or big fixes//