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I need to store plenty of data points (timeseries) coming from a sensor reach device (SensorTag)
Is there any recommended framework to store plenty of fast streaming data?
What type of local storage system do you recommend, sql, file, else?
Details
- Data comes in at 25hz per second
- Each row might have 70 bytes worth of data
- It's a continuous capture for 12 hours straight
When I did something similar with a BTLE device, I used Core Data with one new managed object instance per reading. To avoid excessive Core Data work, I didn't save changes after every new instance-- I'd save at intervals, after 100 new unsaved readings were available.
You might need to tune the save interval, depending on details like how much data the new entries actually have, what else is happening in your app at the time, and what device(s) you support. In my case I was updating an OpenGL view to show a 3D visualization of the data in real time.
Whatever you choose, make sure it lets you get the readings out of memory quickly. 25Hz * 70 bytes * 12 hours is a little over 75Mb. You don't want that all in RAM if you can avoid it.
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I'm working on a Flash Card app, all flash cards should be stored in core data.
An important feature is allow some flash cards sync between devices and some not.
To sync flash cards between devices, I can use NSPersistentCloudKitContainer. But the problem is NSPersistentCloudKitContainer will sync all flash cards and I don't know if there is a way to disable syncing in some flash card.
One solution is to create 2 PersistentContaier, one with NSPersistentCloudKitContainer to store syncable flash cards and the other one is NSPersistentContainer to store non-sync flash cards.
But I'm not sure if this solution optimal is because it could add more complexity in the code later and it's hard to maintain 2 containers (?)
I would appreciate any advice
Manage Multiple Stores section of Setting Up Core Data with CloudKit explains how to synchronize only part of data.
WWDC 2019 session – Using Core Data With CloudKit
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I'm actually creating my first personal project with swift which is an app that will present every prospect in the next NFL draft with info about them. I want to do kind of a database for the users to be able to browse around every player.
What I don't know how to do yet is how should I do to store the data. I thought about realm or coreData but I want to find a solution that will allow me to sync the data from a server to update the info in real-time for the users. There is no user data to update or save. I find the MongoDB Realm platform but I don't find a lot of resources about it. If anyone has any idea for how I should do, already thank you!
Have a nice day,
Matteo!
I've made good experiences with Firestore. Its free (up to a certain usage) and has quite some good and clear documentation.
https://firebase.google.com/docs/firestore/query-data/listen
I agree with the other answer. Firebase is a fantastic realtime database to use for this specific idea. It's extremely easy to get started and the documentation is straight forward. I just started using it a couple weeks ago after switching over from AWS.
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I have a stream of data on which I want to estimate the kernel density(or a histogram). Input parameter is the window length. For example 60-seconds, or 5-minutes or a month. Any data older than the window size should affect the estimation minimally. However, I cannot store the actual data point. Once a new data sample arrives, I want to add it to the estimator and discard it. Since this is a resource constrained environment(both CPU+memory), the method should preferably be O(1) in space and time complexity.
Are there any readymade libraries that already do this job?
I would prefer something in GO, but I would take an implementation in any language.
If there are no existing implementations, is there an algorithm that I can refer to and implement?
(Searching on Google did not give me any direct answer, I am new to machine learning and statistics)
Geometrically decaying histogram would do the job.
$$h(i) = h(i) * (1 - e^{-1/\tau}) + e^{-1/\tau} \delta(i-j)$$
where $j$ is the new observation, $h(i)$ is the running average histogram, and $\tau$ is the time constant.
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I need to keep track of peak memory usage, and average memory usage, CPU time of a specific application. I know there is Windows' perfmon tool, but it keeps record of all the system, but I need to keep record of just one specific application. I also tried kiwimonitor app, it does not provide precise result.
Do you know how to filter perform tool to just keep record of single application's performance statistics? Or is there a useful tool I can use for that purpose?
You can create a user defined data set (under Data Collector Sets) and limit your performance counters for a specific process. Once you select a process object, choose what process you want to monitor and the counters for that specific process.
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Its seems to be a silly question but I need your help as I am a beginner to iOS coding.
(1) My question is I need to know whether iOS have any default DATABASE or not. If yes can you share those links to me.
(2) If not can you suggest most popular database which can handle more than 50MB of data in iPad (Client side).
Thank You,
Madhav
What is the maximum size limit for storing the values in SQLite database for ios?
As per my requirement I need to store more than 50MB of database.Can you suggest which database will allow more than 50MB of database in iPad (Client side).
Is there any Size limit for SQLite Database? As I am hydride app developer by using Phonegap plugins. But I am able to store only 50MB of data by using SQLite database.
Most people I know decide on using Sqlite. Depending on your use case you may want to research:
CoreData backed by sqlite
FMDB - More low level than CoreData but comes with some performance improvements.
Write your own wrapper based on available c interface.
References:
https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreData/Articles/cdPersistentStores.html
https://github.com/ccgus/fmdb