使用 SQL 从数据库视图而不是表中读取

Question

I am trying to read data from a view that I have created based on other views in my database using Python.

Database set-up:

Redshift-postgres
  dev
    Schemas
      schema_name
        Tables
          table_name
        Views
          view_name

Python code:

connection=psycopg2.connect("dbname=dev host=redshift.amazonaws.com port=5439 user=user password=password")

cursor = connection.cursor()
schema = "SELECT count(*) FROM schema_name.table_name;"
schema2 = "SELECT count(*) FROM schema_name.view_name;"
result = pd.read_sql(schema, connection)

When I run the code with schema it returns data from a table but when I try to run schema2 it does not return anything and no error message is provided. The script does not stop it just idles.

Am I doing something wrong when trying to get data from a view rather than a table?

UPDATE

When I run schema2 = "SELECT * FROM INFORMATION_SCHEMA.TABLES;" it does return the following:

table_catalog    table_schema   table_name  table_type 
dev              schema_name    view_name         VIEW    

It lists the view I am trying to read data from.

I created the view like so:

CREATE OR REPLACE VIEW schema_name.view_name
AS SELECT *
        CASE
            WHEN statement
            ELSE false
        END AS column_name, 

   FROM schema_name.another_view_name
   LEFT JOIN schema_name.another_view_name_2 data_1 ON data_2 = data_3
   LEFT JOIN schema_name.another_view_name_3 data_4 ON data_5 = data_6

I have named irelevant data data_x where I join the views based on some conditions.

Answer 1

Turned out that amazon redshift DB got clogged up and had 5 queries that ran for 4 days with no response. Anyhow, I still find that reading from a view with 2 left joins takes like 3 hours to read which is not how it should work. The view has only 1.2m rows. Thank you for your suggestions.