Saving Data on Android

vertical scaling
.
In many NoSQL databases, including Firestore, when you need more storage, 
Firestore spreads your data across many servers. This is known as 
horizontal 
scaling
, and it’s much easier to scale horizontally than vertically. Why? Because it’s 
much easier to get many moderately powerful machines than to continually upgrade 
a single machine to handle everything. Machines have their limits too, you know!
Saving Data on Android
Chapter 16: Introduction to Cloud Firestore
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Collec/ons and documents
You learned that the Realtime Database stores data as one large JSON tree that 
contains keys and values. You also learned that these values can be objects 
containing other key-value pairs. The Firestore is a collection of objects that are 
stored in a hierarchical structure that resembles a tree. Every object in a collection is 
represented as a document. The document consists of key-value pairs known as 
fields
 in the Firestore. These values can be strings, numbers, binary data, or nested 
objects in a map format. The limitation, however, is that the document size must be 
less than 1MB.
In simple terms, collections are nothing more than a group of documents. A 
document cannot contain other documents, but it can contain another collection 
known as 
subcollection
.
Cloud Firestore supports many data types. To learn more about them, visit the 
official 
documentation
 at 
https://firebase.google.com/docs/firestore/manage-data/
data-types
.
Key points
• Cloud Firestore is a NoSQL database similar to the Realtime Database.
• Firestore stores data as a collection of objects which are stored in a hierarchical 
structure that resemble a tree.
• Documents and collections are the main building blocks of Cloud Firestore.
• Documents consist of key-value pairs known as fields.
• Collections are a group of documents.
• Collections can only contain documents.
• The root of the Cloud Firestore database can only consist of collections.
• A document cannot contain other documents, but it can contain another 
collection; these are known as subcollections.
Saving Data on Android
Chapter 16: Introduction to Cloud Firestore
raywenderlich.com
248

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• It’s easier to query, filter and sort data using the Firestore since it can all be done 
within a single request.
• It’s best to use foreign-key-like fields in objects, as you don’t want to duplicate 
data and clutter the database.
• The Firestore scales horizontally; this is easier than the Realtime Database which 
scales vertically.