Monday, November 14, 2016

[SOLUTION] WEEK 5 : INDEXES AND PERFORMANCE : M101JS: MONGODB FOR NODE.JS DEVELOPERS

 [Solution] Week 5 : Indexes and Performance : M101JS: MongoDB for Node.js Developers


Homework 5.1 : 


Suppose you have a collection with the following indexes:

> db.products.getIndexes()
[
    {
        "v" : 1,
        "key" : {
            "_id" : 1
        },
        "ns" : "store.products",
        "name" : "_id_"
    },
    {
        "v" : 1,
        "key" : {
            "sku" : 1
        },
                "unique" : true,
        "ns" : "store.products",
        "name" : "sku_1"
    },
    {
        "v" : 1,
        "key" : {
            "price" : -1
        },
        "ns" : "store.products",
        "name" : "price_-1"
    },
    {
        "v" : 1,
        "key" : {
            "description" : 1
        },
        "ns" : "store.products",
        "name" : "description_1"
    },
    {
        "v" : 1,
        "key" : {
            "category" : 1,
            "brand" : 1
        },
        "ns" : "store.products",
        "name" : "category_1_brand_1"
    },
    {
        "v" : 1,
        "key" : {
            "reviews.author" : 1
        },
        "ns" : "store.products",
        "name" : "reviews.author_1"
    }

Which of the following queries can utilize at least one index to find all matching documents or to sort? Check all that apply.

Solution :








Homework 5.2 : 



Suppose you have a collection called tweets whose documents contain information about the created_at time of the tweet and the user's followers_count at the time they issued the tweet. What can you infer from the following explain output?

> db.tweets.explain("executionStats").find({"user.followers_count":{$gt:1000}}).limit(10).skip(5000).sort( { created_at : 1 } )
{
    "queryPlanner" : {
        "plannerVersion" : 1,
        "namespace" : "twitter.tweets",
        "indexFilterSet" : false,
        "parsedQuery" : {
            "user.followers_count" : {
                "$gt" : 1000
            }
        },
        "winningPlan" : {
            "stage" : "LIMIT",
            "limitAmount" : 0,
            "inputStage" : {
                "stage" : "SKIP",
                "skipAmount" : 0,
                "inputStage" : {
                    "stage" : "FETCH",
                    "filter" : {
                        "user.followers_count" : {
                            "$gt" : 1000
                        }
                    },
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "keyPattern" : {
                            "created_at" : -1
                        },
                        "indexName" : "created_at_-1",
                        "isMultiKey" : false,
                        "direction" : "backward",
                        "indexBounds" : {
                            "created_at" : [
                                "[MinKey, MaxKey]"
                            ]
                        }
                    }
                }
            }
        },
        "rejectedPlans" : [ ]
    },
    "executionStats" : {
        "executionSuccess" : true,
        "nReturned" : 10,
        "executionTimeMillis" : 563,
        "totalKeysExamined" : 251120,
        "totalDocsExamined" : 251120,
        "executionStages" : {
            "stage" : "LIMIT",
            "nReturned" : 10,
            "executionTimeMillisEstimate" : 500,
            "works" : 251121,
            "advanced" : 10,
            "needTime" : 251110,
            "needFetch" : 0,
            "saveState" : 1961,
            "restoreState" : 1961,
            "isEOF" : 1,
            "invalidates" : 0,
            "limitAmount" : 0,
            "inputStage" : {
                "stage" : "SKIP",
                "nReturned" : 10,
                "executionTimeMillisEstimate" : 500,
                "works" : 251120,
                "advanced" : 10,
                "needTime" : 251110,
                "needFetch" : 0,
                "saveState" : 1961,
                "restoreState" : 1961,
                "isEOF" : 0,
                "invalidates" : 0,
                "skipAmount" : 0,
                "inputStage" : {
                    "stage" : "FETCH",
                    "filter" : {
                        "user.followers_count" : {
                            "$gt" : 1000
                        }
                    },
                    "nReturned" : 5010,
                    "executionTimeMillisEstimate" : 490,
                    "works" : 251120,
                    "advanced" : 5010,
                    "needTime" : 246110,
                    "needFetch" : 0,
                    "saveState" : 1961,
                    "restoreState" : 1961,
                    "isEOF" : 0,
                    "invalidates" : 0,
                    "docsExamined" : 251120,
                    "alreadyHasObj" : 0,
                    "inputStage" : {
                        "stage" : "IXSCAN",
                        "nReturned" : 251120,
                        "executionTimeMillisEstimate" : 100,
                        "works" : 251120,
                        "advanced" : 251120,
                        "needTime" : 0,
                        "needFetch" : 0,
                        "saveState" : 1961,
                        "restoreState" : 1961,
                        "isEOF" : 0,
                        "invalidates" : 0,
                        "keyPattern" : {
                            "created_at" : -1
                        },
                        "indexName" : "created_at_-1",
                        "isMultiKey" : false,
                        "direction" : "backward",
                        "indexBounds" : {
                            "created_at" : [
                                "[MinKey, MaxKey]"
                            ]
                        },
                        "keysExamined" : 251120,
                        "dupsTested" : 0,
                        "dupsDropped" : 0,
                        "seenInvalidated" : 0,
                        "matchTested" : 0
                    }
                }
            }
        }
    },
    "serverInfo" : {
        "host" : "generic-name.local",
        "port" : 27017,
        "version" : "3.0.1",
        "gitVersion" : "534b5a3f9d10f00cd27737fbcd951032248b5952"
    },
    "ok" : 1
}

Solution : 








Homework 5.3 :

In this problem you will analyze a profile log taken from a mongoDB instance. To start, please download sysprofile.json from Download Handout link and import it with the following command:

mongoimport --drop -d m101 -c profile sysprofile.json

Now query the profile data, looking for all queries to the students collection in the database school2, sorted in order of decreasing latency. What is the latency of the longest running operation to the collection, in milliseconds?

Solution : 15820

















Enjoy....!!!!

Feel free to comment below your experience with above approach and If you still find any problem  with above steps Let me know I would love to help you to resolve your  problem.

 If you want to take your Technological Knowledge to the Next Level and For More Technological information Stay tuned to Visionfortech

Related Post : 

1) [SOLUTION] WEEK 1 : INTRODUCTION : M101JS: MongoDB for Node.js Developers

2) [SOLUTION] WEEK 2 : CRUD : M101JS: MongoDB for Node.js Developers

3) [SOLUTION] Week 3 :The Node.js Driver : M101JS: MongoDB for Node.js Developers

4) [SOLUTION] WEEK 4 : SCHEMA DESIGN : M101JS: MongoDB for Node.js Developers

5) [SOLUTION] WEEK 5 : INDEXES AND PERFORMANCE : M101JS: MongoDB for Node.js Developers

6) [SOLUTION] WEEK 6 : THE AGGREGATION FRAMEWORK : MongoDB for Node.js Developers

7) [SOLUTION] WEEK 7 :APPLICATION ENGINEERING : MongoDB for Node.js Developers

8) [SOLUTION] FINAL EXAM(PROJECT) :MONGOMART APPLICATION : M101JS: MongoDB for Node.js Developers

3 comments:

  1. Thank you for your valuable information about the node.js development security this is an useful one keep sharing the post like this...Ones again thanks
    node.js development services

    ReplyDelete
  2. Query for 5.3 - db.profile.find({ns:"school2.students"}).sort({millis:-1}).limit(1).pretty()

    ReplyDelete

Protected by Copyscape