sails.js bluebird 承诺链接多个查询很慢

Question

I am new to node.js/ sails.js. I heard node.js is very fast. But i am getting very poor performance. Here i have used bluebird for promise.Basically i want to refactor this so it will be faster. Here i am executing four different query for getting product details(name,model,description etc), product additional images , product options and each options details.

I want to know how can i split these four query to four different methods or functions so i can reuse these later and also when i will call get getProductdetails this will call all four query and get end results faster. Please help me on this. I am stuck to proceed further. Many thanks in advance.

// api/model/product.js
    getProductDetails:function(product_id){
        return new Promise(function(resolve, reject) {
            var product={},options=[];
            //details
          Product.query("select * from product p , product_description pd where p.product_id="+product_id+" and pd.product_id= p.product_id and pd.language_id=1",function(error, details) {
            //images    
            Product.query("SELECT * FROM product_image WHERE product_id = "+product_id+" ORDER BY sort_order ASC",function(error, images) { 

            //options   
            Product.query("SELECT * FROM product_option po LEFT JOIN `option` o ON (po.option_id = o.option_id) LEFT JOIN option_description od ON (o.option_id = od.option_id) WHERE po.product_id = "+product_id+" AND od.language_id = '1' ORDER BY o.sort_order",function(error, options) {
                    options.forEach(function (item) {
                                //options value
                              Product.query("SELECT * FROM product_option_value pov LEFT JOIN option_value ov ON (pov.option_value_id = ov.option_value_id) LEFT JOIN option_value_description ovd ON (ov.option_value_id = ovd.option_value_id) WHERE pov.product_id = "+product_id+" AND pov.product_option_id = "+item.product_option_id+" AND ovd.language_id = '1' ORDER BY ov.sort_order",function(error,option_value){
                                    options.push({options: item, option_value: option_value});
                                });
                        });//foreach option
                product={details:details[0], options: options, images:images};
                resolve(product);
            }); 

        });

        });

        }); 
    }   

Answer 1

Node is "fast" for certain workloads and patterns. A lot of it's speed comes from the way it handles IO and network tasks ( such as database queries ) which increase it's ability to handle scale. [If you are interested in reading more about that and how it works read about the Event Loop - here is a good article]

As far as improving your provided code goes - I have made the assumption you are using Bluebird and have installed Underscore.js to make it slightly neater. For security reasons I would highly recommend switching to an ORM or at least making sure you escape the information in the SQL query. Node is fast but does not solve injection issues :)

I have refactored your code so that request can execute in parallel which should help to speed up your code by leveraging concurrency as in any other language. I have used promises and also taken advantage of the bluebird promisify all system so that you don't need to create a Promise.

var promisifiedProduct = Promise.promisifyAll(Product)
var _ = require('underscore')

getProductDetails: function(product_id) {

    var details_retriever = promisifiedProduct.queryAsync("select * from product p, product_description pd where p.product_id=" + product_id + " and pd.product_id= p.product_id and pd.language_id=1")

    var images_retriever = promisifiedProduct.queryAsync("SELECT * FROM product_image WHERE product_id = " + product_id + " ORDER BY sort_order ASC")

    var options_retriever = promisifiedProduct.queryAsync("SELECT * FROM product_option po LEFT JOIN `option` o ON (po.option_id = o.option_id) LEFT JOIN option_description od ON (o.option_id = od.option_id) WHERE po.product_id = " + product_id + " AND od.language_id = '1' ORDER BY o.sort_order")

    // Iterate over each option for some additional information
    var sub_options_retriever = options_retriever.then(function(options) {

        // Map the options to a Promise that will resolve to the value
        var sub_option_retrievers = _.map(options, function (option) {

            // Return a Promise that resolves to the desired object
            return  promisifiedProduct.queryAsync("SELECT * FROM product_option_value pov LEFT JOIN option_value ov ON (pov.option_value_id = ov.option_value_id) LEFT JOIN option_value_description ovd ON (ov.option_value_id = ovd.option_value_id) WHERE pov.product_id = " + product_id + " AND pov.product_option_id = " + option.product_option_id + " AND ovd.language_id = '1' ORDER BY ov.sort_order")
                .then(function(sub_options) {

                    return {
                        options: option, 
                        option_value: sub_options
                    }

                })

        })

        // Concurrently retrieve the sub options
        return Promisify.all(sub_option_retrievers)

    })

    // Wait for all the information to be retrieved
    var retriever = Promisify.all([details_retriever, images_retriever, options_retriever, sub_option_retriever])

    var result_formatter = retriever.then(function(results) {

        // Create a scope level variable for options so we are not mutating a provided argument
        var options = results[2]

        // Add each sub_option into options - Not sure why?
        var formatted_options = _.forEach(result[3], function(sub_option) {
            options.push(sub_option)
        })

        return {
            details: results[0][0],
            options: formatted_options, 
            images: results[1]
        }
    })

    return result_formatter
}

I haven't tested the code or double checked any of the functions so it may need a little tweaking but it should be good!