Slow getting collection handle

MongoDB Atlas App Services & Realm Atlas Triggers & Functions
1

Hi I am looking for a faster way of getting a collection handle within a realm change stream trigger function.

currently if I use :

const mongodb=context.services.get("cluster");
const inventoryCollection=mongodb.db("db").collection("collection");

it seems to take about 80-100ms, I need it much faster, is there another way of getting a handle to the collection from within the changeEvent function, as the change stream knows the collection its associated with ?

2

Hi @derek_henderson1,

I think it’s the only solution here but these 2 lines of code shouldn’t take more than a few micro seconds I guess.

I guess you mean that the entire round trip takes about 80-100ms (trigger + exec the function + receive the result somewhere). To which I’m going to answer with a few questions: where is located your Atlas cluster and where is located the Realm App? Are they collocated in the same region? If you are using a global Realm App, I would suggest to use a local one instead, collocated in the same region or as close as possible to limit the latency impact on the overall response time.

Cheers,
Maxime.

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3

Thank very much for the response Maxine, yes I mean the full round trip, we ran some tests and when we remove everything but get handle we got 80-100ms when we added back in everything else it only went up by a few ms. All our code is running in the one region Azure/London (uksouth). I’m new to realm I’m just using a realm function in a realm app, not sure how to tell if my realm app is local or global.

4

Thanks @MaBeuLux88 … now i look… its defined a as global … didn’t know about that setting, its placed it in a totally different region … I’ll fix that to a local and try again … thanks again

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5

I think you found already but it’s in the App Settings tab in your Realm app. As of today, Realm Apps can only be deployed in 7 regions. London isn’t one of them but you have Ireland (eu-west-1) which is fairly close and it should reduce the overall latency a lot already.

Cheers,
Maxime.

6

@MaBeuLux88 thanks, its going to take a while as it appears you cant change the region. I’ll have to delete and re build my whole app connected to Ireland rather than currently Virginia :slight_smile: … a valuable learning experience for me. Thanks again.

7

@MaBeuLux88 Thanks for the info, could I trouble you once more, The problem I have is the Triggers_RealmApp is created automatically when I go into Atlas => Triggers => Add Trigger … it defaults it to Virginia, do you know how to change the default location when it creates the Triggers_RealmApp so I can create it in Ireland ?

8

Yup!
Same problem / analysis here.

image

Deploy your own Realm App (with the right region / settings) and then create the triggers & functions in there. Atlas Triggers are actually just triggers deployed in an auto-configured Realm App.

I don’t see the point of having this either to be honest… Just make a real Realm app is my advice :sweat_smile:!

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9

Thanks again, you have been really helpful. Its much appreciated.

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10

I have raised this user experience issue to the Atlas team. They have a plan to improve this and make the Realm App settings editable so you can move it from one region to another.

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11

That’s really good news :blush:

Thanks again for all your help over the last few days, I have everything up and running now.

Derek

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12

You are very welcome! Excellent news!
Best of luck for your project & see you around :slight_smile:!

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