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Reputation: 91

How to count total SELECT query requests for specific collection from MongoDB logs?

I have a MongoDB collection "cars" and below gives me how many documents exist inside it:

let carsColl = db.getCollection('cars');
carsColl.count();

However, I need to know how many times the cars collection is queried in total ? Also, say if I have two cars x and y, may I know how many SELECT queries executed for 'x' vs 'y' documents?

I checked MongoDB triggers but they can only be created for INSERT, UPDATE, REPLACE and DELETE, but not SELECT.

Any guidance will be of great help.

Upvotes: 2

Views: 571

Answers (1)

whoami - fakeFaceTrueSoul
whoami - fakeFaceTrueSoul

Reputation: 17915

So from your question basically you're not looking to query documents in a collection rather looking to query on type of operations being done on cars collection i.e; on logs.

Where as your below code will give no.of documents in cars collection :

let carsColl = db.getCollection('cars');
carsColl.count();

As that's not what you're looking for, then try below :

Steps :

  1. Enable Db profiling, by default your DB will log slow running queries that is any query that runs > 100ms, So you need to log all queries in this case. Execute below query to log all queries on DB :

    db.setProfilingLevel(2)

    Note : Doing this can effect your DB performance as it will be logging all operations, which might become an issue for Prod servers having high amount of DB calls. Ref : manage-the-database-profiler . Also check on how to execute above query as it might need user admin access.

  2. Now once you do above step, You can execute these queries :

    1. To get count of all read queries on collection cars which is inside test DB, try below query. Here op: 'query' refers to all find calls (Remember that aggregation is different it has op : command).

      db.system.profile.find( { ns : 'test.cars', op: 'query' }).count()

    2. To get count of specific queries : In this case let's say your collection has few documents with a field carType : x & few others has carType : y and you're querying on them like this db.cars.find('carType': 'x'), then :

      db.system.profile.find( { ns : 'test.cars', op: 'query' , 'command.filter.carType' : 'x' }).count() // will give you all queries on x

db.system.profile.find( { ns : 'test.cars', op: 'query' , 'command.filter.carType' : 'y' }).count() // will give you all queries on y

Note : Basically you'll be giving your filter query over db.system.profile.find() to differentiate between your needed finds (Vs) all other find logs.

Upvotes: 1

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