How to stop imposm3 from creating an index osm_*_geomon on geometry?

stillhart · December 10, 2024, 9:56pm

I’m using imposm3 to import buildings into postgis. I’m planning to import the whole world. Now it seems like imposm3 automatically creates a gist index called “osm_buildings_geom” on my buildings import. I have the feeling that it slows down the import. I don’t even need that index. Is there a way to stop imposm3 from doing that?

Here’s my mapping.yml for reference

---
tables:
  buildings:
    type: polygon
    columns:
    - name: osm_id
      key: 
      type: id
    - name: geometry
      key: 
      type: geometry
    - name: name
      key: name
      type: string
    - name: type
      key: building
      type: string
    - name: housenumber
      key: addr:housenumber
      type: string
    - name: street
      key: addr:street
      type: string
    - name: city
      key: addr:city
      type: string
    - name: postcode
      key: addr:postcode
      type: string
    - name: country
      key: addr:country
      type: string
    mapping:
      building:
      - __any__
    filters:
      building:
      - ruins
      - tent
      - roof
      - greenhouse
      - garages
      - garage
      - carport

ImreSamu · December 10, 2024, 10:03pm

you can modify the source code - removing the gist index creation.

github.com

omniscale/imposm3/blob/afffadb04e094d7cafdb0770a608ac17b26b21e2/database/postgis/postgis.go#L208


      
          func createIndex(pg *PostGIS, tableName string, columns []ColumnSpec, generalizedTable bool) error {
          	foundIDCol := false
          	for _, cs := range columns {
          		if cs.Name == "id" {
          			foundIDCol = true
          		}
          	}
          
          	for _, col := range columns {
          		if col.Type.Name() == "GEOMETRY" {
          			sql := fmt.Sprintf(`CREATE INDEX "%s_geom" ON "%s"."%s" USING GIST ("%s")`,
          				tableName, pg.Config.ImportSchema, tableName, col.Name)
          			step := log.Step(fmt.Sprintf("Creating geometry index on %s", tableName))
          			_, err := pg.Db.Exec(sql)
          			step()
          			if err != nil {
          				return err
          			}
          		}
          		if col.FieldType.Name == "id" && (foundIDCol || generalizedTable) {
          			// Create index for OSM ID required for diff updates, but only if

sql := fmt.Sprintf(`CREATE INDEX "%s_geom" ON "%s"."%s" USING GIST ("%s")`,

Jochen_Topf · December 11, 2024, 8:02am

If that’s an option for you, you could switch to osm2pgsql which allows fine-grained control over which indexes are created.