迭代「大」集合時Rails 4和Mongo DB 4.x錯誤

具有大約800-900條記錄的Mongo備份模型我試圖迭代並使用某些屬性生成CSV。迭代「大」集合時Rails 4和Mongo DB 4.x錯誤

所以它看起來像這樣：

each do |car| 
    csv << columns.map { |column| car.__send__(column) } 
end

而且我得到的錯誤是這樣的：

A Moped::Errors::QueryFailure occurred in cars#index: 

    The operation: #<Moped::Protocol::Query 
    @length=94 
    @request_id=376 
    @response_to=0 
    @op_code=2004 
    @flags=[] 
    @full_collection_name="app555555.cars" 
    @skip=0 
    @limit=0 
    @selector={"$query"=>{}, "$orderby"=>{"created_at"=>-1}} 
    @fields=nil> 
failed with error 10128: "too much data for sort() with no index. add an index or specify a smaller limit" 

See https://github.com/mongodb/mongo/blob/master/docs/errors.md 
for details about this error. 
    app/models/car.rb:84:in `block in to_csv'

來源

2015-10-13 Vahan Vardanyan