I'm creating an android app which uses Firebase Firestore database to store data. I store about 3600 questions and about 400 images. I know that firestore support offline. But I'm not sure whether the database download itself or not every time I request data from it. And under which circumstance does the firestore database get downloaded from the cloud? Does the database get only updated when the cloud database change?
Every query performed while the app is online will download all the necessary data from the database to satisfy that query.
Any data cached locally as a result of a prior query is only used when the app is offline. As suggested by the documentation, the idea is for your app to be usable when internet connectivity is interrupted. The assumption is that the connectivity will eventually come back, and queries will revert to using the online database as the primary source of data.
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I have a clarifying question about Cloud Firestore and Flutter:
I am making an app that users can create log entries of sort, which will be saved on Firebase. But they might make up to 30 entries offline, before they have internet connection again.
And I know that Firestore has an offline feature, with which any created documents can be viewed offline because it is saved in the order of logging, and then synced with the database when internet connection is gained. But it is absolutely crucial that these logs cannot be lost in my app before having a chance of uploading it. Is there a way to ensure that my app will not lose this data before connecting to Firebase again, or should I create a Sembast database on the device, and save a copy of everything, and then check that once in a while against the database?
Does Firestore have offline contingency for if the phone's battery dies before it could sync with Firestore?
Or is there another solution I am unaware of?
For Android and iOS, offline persistence is enabled by default.
You don't have to do anything in your code.
Note there is a default cache size of 100 MB. This can be changed though, eg
let settings = Firestore.firestore().settings
settings.cacheSizeBytes = FirestoreCacheSizeUnlimited
Firestore.firestore().settings = settings
Does Firestore have offline contingency for if the phone's battery dies before it could sync with Firestore?
When Firestore's offline persistence is enabled, it stores data that your app has recently read, as well as any pending writes, to a database on the local device or browser. This disk based cache will survive restarts of the app/reloads of the page.
For new version of use below code -
FirebaseFirestore.instance.settings =
Settings(cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED);
I was able to configure the Firestore database in Firebase with my flutter app and also create and read documents from my collection but when I go to Firestore console I don't see the created data, also when I creat data manually I am unable to see it in my application.
I am using the test mode which means any user can read or write.
I hope someone can help me with this puzzle.
Thanks!!!
It sounds like the device/emulator that you are running on is not connected to the internet, or at least not to the Firestore servers. In that case, the client writes all local changes into a local database, waiting to send them to the server when it gets a connection. So the local app will work, but won't be able to synchronize its local cache with the database servers.
You might want to check the connection on your device, and any proxies that might exist between your app and the Firestore servers.
Is it possible to force the Firestore Database to cache an entire database offline?
Currently, Firestore caches what has already been accessed in the app. I want to use data offline that the user may not have accessed before going offline.
I'm using Flutter for the app.
The only way to locally cache data from Firestore is to actually query for that data. You will need to execute queries for all the documents you wish to cache. There is currently no alternative to this.
It seems odd to me that Firestore would charge me for read queries to locally cached data, but I can't find any clarification to the contrary in the Firestore Pricing document. If I force Firebase into offline mode and then perform reads on my locally cached data, am I still charged for each individual entity that I retrieve?
Second, offline users in my app write many small updates to a single entity. I want the changes to persist locally each time (in case they quit the app), but I only need eventually consistent saves to the cloud. When a user reconnects to the internet and Firestore flushes the local changes, will I be charged a single write request for the entity or one per update call that I made while offline?
Firestore could potentially fit my use case very well, but if offline reads and writes are charged at the same rate as online ones it would not be an affordable option.
As the offical documentation says,
Cloud Firestore supports offline data persistence. This feature caches a copy of the Cloud Firestore data that your app is actively using, so your app can access the data when the device is offline. You can write, read, listen to, and query the cached data. When the device comes back online, Cloud Firestore synchronizes any local changes made by your app to the data stored remotely in Cloud Firestore.
So, every client that is using a Firestore database and sets PersistenceEnabled to true, maintains it's own internal (local) version of the database. When data is inserted/updated, it is first written to this local version of the database. As a result, all writes to the database are added to a queue. This means that all the operations that where stored there will be commited on Firebase servers once you are back online. This also means that those operations will be seen as independent operations and not as a whole.
But remeber, don't use Firestore as an offline-only database. It is really designed as an online database that came work for short to intermediate periods of being disconnected. While offline it will keep queue of write operations. As this queue grows, local operations and app startup will slow down. Nothing major, but over time these may add up.
If Google Cloud Firestore priceing model does not fit your use case very well then use Firebase Realtime Database. As mentioned also in this post from the Firebase offical blog, one the reasons you still might want to use the Realtime Database is:
As we noted above, Cloud Firestore's pricing model means that applications that perform very large numbers of small reads and writes per second per client could be significantly more expensive than a similarly performing app in the Realtime Database.
So it's up to you which option you choose.
According to this If you want to work completely offline with Cloud Firestore you can disable network by :
FirebaseFirestore.getInstance().disableNetwork()
but firestore will cause client offline error for first user get request, that you must consider this error as empty response.
I'm thinking moving an Android app's persistent data to Firebase Database. Currently I use Sqlite with a Python HTTP REST service.
In the app, I have a big list of cities, called citiesList. Since the list is quite big and hardly updated, I don't want the app fetch the list whenever it goes online.
My current strategy is provide a citiesListVersion. When the app goes online, it checks citiesListVersion. If the server's citiesListVersion is newer, the app will fetch citiesList from server. Otherwise, the app continues working with the cached data.
My question is: can I keep my current strategy when moving to Firebase Database? As I understand, Firebase tries to sync data whenever the app goes online.