I wanted to store the specific path in Firebase database (JSON) in local phone storage, not all data at the realtime-Firebase database. Say I have a news-feed path for each user in my Firebase-database and I want to save only the news-feed which is specified for the user instead of loading whole useless data on the local storage of user's mobile.
I read this paragraph from the official Firabase site which mentioned that
The Firebase Real-time Database synchronizes and stores a local copy of the data for active listeners. In addition, you can keep specific locations in sync.
DatabaseReference scoresRef = FirebaseDatabase.getInstance().getReference("scores");
scoresRef.keepSynced(true);
If this is the solution to my question, then I can use this line directly without writing that line
FirebaseDatabase.getInstance().setPersistenceEnabled(true);
Those two bits of code are not really related. They don't do the same thing.
keepSynced(true) effectively keeps a listener active on the given reference, from the moment it's called, for as long as the app is running, so that the local version of the data is always in sync with the remote version on the server.
setPersistenceEnabled(true) just activates local caching of the data read by the SDK. When persistence is enabled, the app can still query data previously read. It takes effect for all data read by the SDK. While persistence is enabled, you can't control which data is cached - all read data is cached up to 10MB max. When the max is reached the oldest data will be evicted from the cache.
According to me the best way will be to parse the Firebase JSON data and map it into an object and then save only data that you need in a local storage (News-feed in your case), and then access it later whenever you need it.
For this, you can use Paper DB as a local storage to store specific data and use it whenever you need to. It stores data as a key value pair so you can access your data with the same key you inserted it with in the database. (Just like shared preferences work).
It stores data as cache in your local storage and uses Kryo serialization framework which is pretty fast for I/O operations.
Or you can also use Room (a google library) with SQLite to achieve this task.
Haven't tried Room but i think it will suite your purpose.
Here's the official documentation for Room
Related
I am using Firebase rtdb. I want to download my database for offline capabilities. If there are no changes on the database, do I get charge to the queries done on local copy of realtime database? And if an update is done on the database, with offline capabilities enabled, is the whole database gets downloaded again or just the part that was changed?
Queries that only use locally cached data are not billed in any way. Only queries that actually use the Firebase cloud-based services are billed. The local cache is only synchronized with the pieces of data that actually changed, not the entire thing every time.
The android app I am currently developing will mainly run offline. However while online, the users can connect to the DB to download the data they need. Furthermore they are able to manage the data offline, so they can remove the data they don't want to use. The users cannot modify the online database.
I am using Firebase with its Persistence enabled feature, to save the date for online use. My problem is, that I just cannot manage the data properly.
Since firebase downloads the whole database:
Is there a way to choose, which queries I want to download form firebase?
If not, can I delete those queries I don't want to use, from local content?
It looks like you don't want the sync feature of the firebase database.
However while online, the users can connect to the DB to download the
data they need. Furthermore they are able to manage the data offline,
so they can remove the data they don't want to use. The users cannot
modify the online database.
set write as false for this table in the rules and the modification will not be possible, since you have enabled disk persistence firebase will read the newer updates but wont write the user changes. Also it might discard the existing changes of the user(which the user removed) during the sync and put the newer ones from the cloud, so you might(as I have never tried this) end up doing the sync yourself, please search and read up on this.
Since firebase downloads the whole database: Is there a way to choose,
which queries I want to download form firebase? If not, can I delete
those queries I don't want to use, from local content?
You will have to turn off on the sync on the each of your table like shown below
DatabaseReference dbRef=FirebaseDatabase.getInstance().getReference("table-name");
dbRef.keepSynced(false);
Refer here in the docs. I think this has to be done on each node as there is no way to turn it off on the entire firebase realtime DB except disable disk persistance which you want in your case.
IMHO it looks like you are using firebase as a place to store your data in the cloud, in case the sync feature ends up discarding your local changes to sync the online ones you should consider using SQL-lite DB with Room ORM as it will serve your purpose of just fetching the data and modifying it locally, however the tradeoff here is that you will have to maintain the data in a proper manner to query the newer changes or see if there is any updates/deletes on any of the older records.
I am developing a chat app that uses firebase database to store data. The usual approach while developing a chat app is to keep the database nodes synced so that you access the messages offline. So the problem rises when I implement the firebase offline capabilities to keep the data nodes synced. Firebase suggests two required steps for accessing data offline:
Enabling disk persistance
this is enabled according to the documentation by using this line of code (in my case I add it in application class):
FirebaseDatabase.getInstance().setPersistanceEnabled(true);
and
Keeping a node synced
this is enabled by simply adding keepsynced(true) to any databasereference that you wish to keep synced, like this:
ChatNode.keepSynced(true);
What is the difference between the two?
According to the firebase team answers on this site, I deduced that:
1) (Disk persistance) stores the data on the device disk to use them when needed, and data is stored wether you write data or read data.
a) If you write data offline: data is stored on disk and is sent to database when you go online again.
b) If you read data offline: the listener that was read online and was kept in disk and stored, you will be able to read it offline from disk.
2) (keep synced true) will keep a database reference synced in 2 ways:
a) If you are also using (disk persistence) with (keep synced) you will be able to keep data synced on disk ... which seems to be the default behavior of (disk persistence).
b) If you are using (keep synced) alone then you only store to what is known as the app memory.
The problem
I did set both of the methods, but my app is now very laggy and slow and sometimes stops on its own.
The question
If all the things that I said above are true, then would this method of offline capability be a heavy load on my app?
If I kept many listeners synced and set persistence enabled, then would the disk become full of data? Should I clean the data? Is the data on disk cleaned by itself in both methods? Is data cleaned by itself from memory?
I want to avoid the lagging and slow response in my app, thanks for your help.
You are right about your assumptions. If you are using FirebaseDatabase.getInstance().setPersistenceEnabled(true); means that Firebase will create a local copy of your database which also means that every change that is made while you are offline, will be added to a queue. So, as this queue grows, local operations and application startup will slow down. So the speed depends on the dimension of that queue. But rememeber, Firebase is designed as an online database that can work for short to intermediate periods of being disconnected and not as an offline database.
Second, if are using many listeners, don't forget to remove the listener accordingly to the life-cycle of your activity like this:
databaseReference.removeEventListener(valueEventListener);
I am working on a budget management application, which needs to store users incomes and expenses then show back to user. I am using SQLite in my project which takes lots of code to save and retrieve data. I wonder whether I can use Firebase just to save and retrieve data. Any answer is appreciated.
Yes, sure you can! Just just use the Firebase Realtime Database service. Think of it like a JSON-ish storage in the cloud :-)
As a bonus, you can enable offline persistence and query your data even offline:
Firebase applications work even if your app temporarily loses its network connection. In addition, Firebase provides tools for persisting data locally, managing presence, and handling latency.
The Firebase Realtime Database stores data returned from a query for use when offline. For queries constructed while offline, the Firebase Realtime Database continues to work for previously loaded data. If the requested data hasn't loaded, the Firebase Realtime Database loads data from the local cache. When network connectivity is available again, the data loads and will reflect the query.
You can enable disk persistence with just one line of code:
FirebaseDatabase.getInstance().setPersistenceEnabled(true);
Firebase database writes, while offline, would be added to a queue which would sync once network is back and online.
We use Firebase as our database on our Android app. We have 2 types of data:
Static data, which changes rarely (less than once a week).
Dynamic/Live data, which keeps on changing on a second-by-second basis.
We have enabled persistence so users can access the static data even when they are offline. However, doing this causes Firebase to cache the dynamic data as well; which means that, whenever any part of dynamic data is queried, and it has been queried before, the user first receives previously cached, stale data and then gets accurate, live data.
We only want persistence for the data under static references, and not for the data under live references. Is it possible to either:
Have persistence enabled only on a particular reference within the database, so that the live data is never cached?
Maintain 2 completely different database instances of Firebase on android, and have persistence enabled on only one of them?
You can use SYNC feature of Firebase. Just turn it off by adding keepSynced(false) and will do the job.
Brief Description:
Firebase synchronizes and stores a local copy of the data for active listeners. In addition, you can keep specific locations in sync.
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Firebase scoresRef = new Firebase("https://dinosaur-facts.firebaseio.com/scores");
scoresRef.keepSynced(true);
The client will automatically download the data at these locations and keep it in sync even if the reference has no active listeners. You can turn synchronization back off with the following line of code.
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scoresRef.keepSynced(false);
By default, 10MB of previously synced data will be cached. This should be enough for most applications. If the cache outgrows its configured size, Firebase will purge data that has been used least recently. Data that is kept in sync, will not be purged from the cache.
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