The document discusses different types of views in databases including stored views, temporary views, and global temporary views. Stored views are persisted objects created with CREATE VIEW, temporary views are session-scoped and dropped when the session ends using CREATE TEMP VIEW, and global temporary views are cluster-scoped, dropped when the cluster restarts, and created with CREATE GLOBAL TEMP VIEW. Views allow running logical queries against source tables without needing to access the actual tables.

1. Views

2. Learning Objectives
u Views
u Types of views

3. View
u Logical query against source tables
A1 A4 B2 B3
A1 A2 A3 A4 B1 B2 B3 B4
table_1 table_2
view_x
CREATE VIEW view_x
AS SELECT A1, A4, B2, B3
FROM table_1
INNER JOIN table_2 …

4. Types of views
1. (Stored) Views
2. Temporary views
3. Global Temporary views

5. 1- (Stored) Views
u Persisted objects
u CREATE VIEW view_name
AS query

6. 2- Temporary view
u Session-scoped view
u CREATE TEMP VIEW view_name
AS query

7. Spark Session
u Opening a new notebook
u Detaching and reattaching to a cluster
u Installing a python package
u Restarting a cluster

8. 3- Global Temporary views
u Cluster-scoped view
u CREATE GLOBAL TEMP VIEW view_name
AS query
u SELECT * FROM global_temp.view_name

9. Views comparison
(Stored) Views
u Persisted in DB
u Dropped only by
DROP VIEW
u CREATE VIEW
Global Temp views
u Cluster-scoped
u dropped when
cluster restarted
u CREATE GLOBAL
TEMP VIEW
Temp views
u Session-scoped
u dropped when
session ends
u CREATE TEMP VIEW