What does Percentage scanned from cache in the query profile signify?

What does Percentage scanned from cache in the query profile signify?
A . The percentage of data scanned from the local disk cache
B. The percentage of data scanned from the METADATA cache
C. The percentage of data scanned from the QUERY cache

View Answer

Answer: A

Explanation:

Understanding caching in snowflake is very important for this exam. So, we will not mug up the answer let us see this through a real experiment. Create a table called inventory as below create table inventory (

BibNumber NUMBER,

Title varchar(200),

Author varchar(200),

ISBN varchar(50),

PublicationYear varchar(20),

Publisher varchar(100),

Subjects varchar(100),

ItemType varchar(10),

ItemCollection varchar(10),

FloatingItem varchar(10),

ItemLocation varchar(10),

ReportDate varchar(35),

ItemCount NUMBER

);

Load at least a million records from a CSV file using the PUT command. Please do not be lazy:), please do this as it will help you with some hands-on exercise.

After this, run the below query and look at the query profile. Your query profile will look like below SELECT * FROM inventory;

Note the Percentage scanned from cache, it is 0% because this is the first time that I have run the query

Run the query again, but switch off the result cache first by running the ALTER SESSION query

ALTER SESSION SET USE_CACHED_RESULT=FALSE; — This ensures that your query result is not

brought from the result cache

Now run

SELECT * FROM inventory;

Look at query profile and see what the Percentage scanned from cache shows. Look at Remote Disk IO as well, it is 2% now vs 8% earlier. So, what is going on here?