Firebase Fan out - the most cost effective way?

Question

I know this issue may have been raised multiple times but I have read on most of the questions available but did not found any that can exactly help to answer my question. As proposed by the Firebase team the fan out technique is the recommended way to ensure fast data read, but with the cost of data duplication. I know this question is subjective and depends on the application, but which is the best solution in terms of cost saving($) and data read?

1. Post same node in multiple child (save data read only called once, but have redundant, so consume more Firebase storage) (see image Firebase Database - the "Fan Out" technique)
2. Post only one node, and other reference to the node by its key (not redundant and consume less Firbase storage, but need to read twice - get the key, and get the node for the key) (see image https://stackoverflow.com/a/38215398/1423345)

For context, I am building a non profit marketplace app, so I need to apply the best solution in terms of balancing both between cost saving ($) and fast data read.

On the other hand, read twice (bandwidth) vs bigger storage? Which one is more cost effective?

Answer 1

I would start by saying that ideally in Firebase you read or sync only what's necessary. So your database queries are coupled by other filters to make the query as specific as possible. If you can nail that then you will anyway build a very intelligent data structure which will be cost effective.

Now the real debate Fan - Out technique or just post reference to the nodes. As I personally prefer Fan-Out and also use it successfully so I will answer in reference to that technique only which will also give you indications of the reason that make me not wanna use keeping a reference and all.

• First and foremost thing is end-user experience and performance. Which comes in the form of the Big Data Chunk Synchronization. Well in general it means that instead of downloading small chunks you aim for the biggest possible so that you reduce High Cell radio usage, High Battery Drain, High bandwidth and also keep the app updated and in sync as fast as possible.

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If you aim for that kind of app performance then you clearly see that Fan-Out is the clear winner over other technique due to following reasons.

1. You download A Big Data Chunk stored in other node which doesn't let your cell radio stay on for long.
2. As you download whole info at once, your app performs better than others. Obviously by whole I don't mean that you should download full database. It's all about that smart balance which makes you download just what is required in first go.
3. It's not that this is the only technique which will give you faster reads and better data structure. There are other techniques like indexing, data validation and security rules which are equally important. All coupled up properly with correct data structure will give you far better performance.
4. In a situation where you have just a reference to other node and not actual data, then you might end up in a situation where you don't actually have anything to show to your users. Let's say your users aren't getting good connectivity so after one read which gave you just the reference, the network falls. So till the network is up again your users don't see anything and trust me that is a very bad situation for the app. Your aim as a developer should be to reduce the chances of those situations

So, I would recommend you to go for FAN - OUT technique as it is faster and cost effective when you see other factors like data filtering, indexing and security rules as well. Yes it comes with a slight price of high storage usage. But what does a less storage mean when you don't have happy users ? Still it all comes down to personal preference. But I have shared my experience and thoughts hope it helps you make right decision.

I would encourage you to got through this and have a more deeper understanding of no SQL Data modelling

Do let me know if this info helped you.