Google App Engine: Storage

Question 1

What are the methods of implementing storage in PaaS?

Answer 1

• Implementing the DB or storage as part of the application
• Google Datastore
• Google Cloud Storage

Question 2

How could you implement a DB or storage as part of an application?

Answer 2

Use a file-based DB (SQLite)

Question 3

What are the cons of implementing the DB or storage as part of the application

Answer 3

<b>- Persistence</b>
The database starts back at zero every time the application creates a new instance

<b>- Instancing</b>
Cant have a singular database used by all instances since each instance is in its own sandbox

Question 4

When does implementing the DB or storage as part of the application work?

Answer 4

When you only need to read from a database, not write to it

Question 5

Datastore is a __ database

Answer 5

NoSQL

Question 6

What is a NoSQL database

Answer 6

• Based around objects that contain whatever data fields they want (JSON)
• Deals with keys&values instead of tables&rows

Question 7

Why use datastore?

Answer 7

You can store data and variables in a persistent manner across all instances

Question 8

How do you fetch from the datastore?

Answer 8

1. Fetch data using a query based on the entity key

2. Store data object in entity and fetch it with the get() function

Question 9

Which database is well suited for storing files?

Answer 9

Google Cloud Storage

Question 10

How does Google Cloud Storage work?

Answer 10

Uses ‘buckets’ to persistently store and serve files for your application

Question 11

How do we fetch a file from Google Cloud Storage?

Answer 11

1. Create a client object
2. Fetch bucket using the get_buket() function with bucket ID as a parameter
3. Fetch a blob of data using get_blob() with the file name as a parameter
4. Fetch bytes from the blob with a download

Question 12

How do you fetch data from the datastore?

Answer 12

Use the client’s get() function to retrieve the entity stored under that key

Returns entity object or none

Question 13

The entity returned by the get() function can be handled like a __ or __ in Python

Answer 13

• Dict

- Dictionary

Question 14

What are the 2 arguments the key() functions take?

Answer 14

• type

- name

Question 15

What argument is required to use the get() function?

Answer 15

key

Question 16

How do you insert entities into Datastore?

Answer 16

Use the put() function with the entity as a parameter

Question 17

How do you create an entity?

Answer 17

Create an entity using the Entity() function with the key as a parameter

var = datastore.Entity(key=ent)