Data Organization Google Professional Data Engineer GCP

Records, called “entities” in Datastore, are retrieved by using a key.
The key is a complex data structure that can be used to model relationships.
The simplest key has a string kind value and either a numeric id value or a string name value.
Multiple records can be found that match criteria
Records can also be ordered.

Concept	Datastore	Firestore	Relational database

Category of object	Kind	Collection group	Table
One object	Entity	Document	Row
Individual data for an object	Property	Field	Column
Unique ID for an object	Key	Document ID	Primary key

Datastore entities of the same kind can have different properties
Entity – single object (like row or document)
Kind – category of object (Like table name)
Property – individual data for an object(like column)
Key – unique ID for each entity
Different entities can have properties with the same name but different value types.
All queries are served by previously built indexes,
Datastore is schemaless.
Has limited support for queries and transactions
Does not support join, inequality filtering on multiple properties or aggregation operations
Datastore is apt for

applications that rely on highly available structured data at scale.
Product catalogs for real-time inventory and product details for a retailer.
User profiles giving a customized experience based on the user’s past activities and preferences.
Transactions based on ACID properties, for example, transferring funds from one bank account to another.