demonstrates how to do chunked queries against large gis datasets in PostGIS and load the data into GeoCouch. written for http://maxogden.com/#/2010-08-14-simplifying-gis.html

postgis_to_geocouch.rb

require 'pg'
require 'json'
require 'couchrest'

pg = PGconn.new("dbname=awesome")
db = CouchRest.database! "http://localhost:5984/awesome"

row_count = pg.exec("select count(*) from awesome")[0]['count'].to_i
offset = 0
while offset < row_count
  geometry = pg.exec("SELECT ST_AsGeoJSON(geometry) from awesome limit 1000 offset #{offset}").map {|r| r}
  rows = pg.exec("SELECT * from awesome limit 1000 offset #{offset}").map {|r| r}
  rows.each_with_index do |row, index|
    row["geometry"] = JSON.parse(geometry[index]["st_asgeojson"]) rescue {"type" => "point", "coordinates" => [0,0]}
    db.save_doc(row)
  end
  offset += 1000
end

db.save_doc({
  "_id" => "_design/geojson",
  "spatial" => {
    "points" => "function(doc) { emit(doc.geometry, {id: doc._id, geometry: doc.geometry});};"
  }
})