Explanation:
Snowpipe supports loading from the following stage types:

Explanation:
Let us see why?
Storage fees are incurred for maintaining historical data during both the Time Travel and Fail-safe periods.The fees are calculated for each 24-hour period (i.e. 1 day) from the time the data changed. The number of days historical data is maintained is based on the table type and the Time Travel retention period for the table.
If you create a permanent table, it will have by default fail safe period of 7 days. That means it needs to allocate space to keep historical data for 7 days. Transient table, on the other hand, does not have fail safe period. Hence using transient table will be the most optimal approach from a cost perspective. Temporary table cannot be used here because temporary tables expire as soon as the session ends.

Explanation:
Snowflake recommends prioritizing keys in the order below:
Cluster columns that are most actively used in selective filters. For many fact tables involved in date-based queries (for example "WHERE invoice_date > x AND invoice date <= y"), choosing the date column is a good idea. For event tables, event type might be a good choice, if there are a large number of different event types. (If your table has only a small number of different event types, then see the comments on cardinality below before choosing an event column as a clustering key.)
If there is room for additional cluster keys, then consider columns frequently used in join predicates, for example "FROM table1 JOIN table2 ON table2.column_A = table1.column_B".

Explanation:
Try it out yourself
On your demo instance, run the below queries
CREATE TABLE SNOWFLAKE (FLAKE_ID INTEGER, UDEMY_COURSE VARCHAR);
INSERT INTO SNOWFLAKE VALUES(1111, 'SNOWFLAKE');
SELECT * from snowflake;
SELECT * from Snowflake;
SELECT * from "snowflake";
SELECT * FROM "SNOWFLAKE";

Explanation:
Try it yourself
Execute the below commands
CREATE TABLE TEST_01 (NAME STRING(10));
DESCRIBE TABLE TEST_01;