Creating tables (permanent, temporary, transient) in Snowflake - Quick Revision & Summary

Recall & Review

beginner

What is a permanent table in Snowflake?

A permanent table stores data persistently until explicitly deleted. It keeps data safe even after sessions end or system restarts.

beginner

How does a temporary table differ from a permanent table?

A temporary table exists only during the user session. It is automatically dropped when the session ends, so data is not saved permanently.

intermediate

What is a transient table in Snowflake?

A transient table stores data persistently but does not have fail-safe protection. It is useful for data that can be lost without major impact.

intermediate

Which table type in Snowflake has fail-safe protection?

Permanent tables have fail-safe protection, which helps recover data after accidental loss for a limited time.

beginner

Write the basic SQL command to create a temporary table named 'temp_sales' with columns 'id' (integer) and 'amount' (decimal).

CREATE TEMPORARY TABLE temp_sales (id INT, amount DECIMAL(10,2));

Which Snowflake table type is automatically dropped at the end of the session?

A Permanent table

B Transient table

C External table

D Temporary table

Temporary tables exist only during the session and are dropped automatically when the session ends.

Which table type does NOT have fail-safe protection?

A Transient table

B Permanent table

C Temporary table

D All have fail-safe

Transient tables do not have fail-safe protection, unlike permanent tables.

What keyword is used to create a transient table in Snowflake?

A CREATE TEMPORARY TABLE

B CREATE TRANSIENT TABLE

C CREATE PERMANENT TABLE

D CREATE EXTERNAL TABLE

The keyword TRANSIENT is used to create transient tables.

Which table type is best for storing data that must be kept permanently and safely?

A Permanent table

B Transient table

C Temporary table

D External table

Permanent tables store data persistently with fail-safe protection.

What happens to data in a temporary table after the session ends?

A Data is saved permanently

B Data is moved to permanent table

C Data is lost and table is dropped

D Data is archived automatically

Temporary tables and their data are dropped when the session ends.

Explain the differences between permanent, temporary, and transient tables in Snowflake.

Think about how long the data lasts and protection levels.

Write the SQL commands to create one permanent, one temporary, and one transient table named 'perm_table', 'temp_table', and 'trans_table' with a single column 'id' integer.

Use the keywords TEMPORARY and TRANSIENT for special tables.

Practice

1. Which type of table in Snowflake is best suited for storing data that needs to persist permanently and be recoverable after accidental deletion?

easy

A. TEMPORARY table

B. PERMANENT table

C. TRANSIENT table

D. EXTERNAL table

Solution

1. Step 1: Understand table types in Snowflake

   Permanent tables store data permanently and include fail-safe for recovery.

2. Step 2: Compare with other table types

   Temporary tables last only for the session, and transient tables do not have fail-safe, so they are not recoverable after deletion.

3. Final Answer:

   PERMANENT table -> Option B

4. Quick Check:

   Permanent = long-term, recoverable [OK]

Hint: Permanent tables keep data safe and recoverable long-term [OK]

Common Mistakes:

• Confusing transient with permanent tables
• Thinking temporary tables persist beyond session
• Assuming transient tables have fail-safe

2. Which of the following is the correct syntax to create a temporary table named session_data with columns id INT and value STRING in Snowflake?

easy

A. CREATE TABLE session_data TEMPORARY (id INT, value STRING);

B. CREATE TABLE TEMP session_data (id INT, value STRING);

C. CREATE TEMPORARY TABLE session_data (id INT, value STRING);

D. CREATE TEMP session_data (id INT, value STRING);

Solution

1. Step 1: Recall Snowflake syntax for temporary tables

   The correct keyword is TEMPORARY placed right after CREATE and before TABLE.

2. Step 2: Check each option's syntax

   CREATE TEMPORARY TABLE session_data (id INT, value STRING); uses correct order and keywords. Options A, B, and C use incorrect or unsupported syntax.

3. Final Answer:

   CREATE TEMPORARY TABLE session_data (id INT, value STRING); -> Option C

4. Quick Check:

   CREATE TEMPORARY TABLE = correct syntax [OK]

Hint: Use CREATE TEMPORARY TABLE for temporary tables [OK]

Common Mistakes:

• Using TEMP instead of TEMPORARY
• Placing TEMPORARY after table name
• Omitting TABLE keyword

3. What will be the result of the following Snowflake SQL commands?

CREATE TRANSIENT TABLE temp_cost (item STRING, price NUMBER);
INSERT INTO temp_cost VALUES ('apple', 1.2);
SELECT * FROM temp_cost;

medium

A. Syntax error due to TRANSIENT keyword

B. Error: Table does not exist

C. Empty result set

D. [{'item': 'apple', 'price': 1.2}]

Solution

1. Step 1: Understand transient table behavior

   Transient tables behave like permanent tables but without fail-safe. They accept inserts and can be queried normally.

2. Step 2: Analyze the commands

   The table is created, a row is inserted, and then selected. No errors or empty results expected.

3. Final Answer:

   [{'item': 'apple', 'price': 1.2}] -> Option D

4. Quick Check:

   Transient tables store and return inserted data [OK]

Hint: Transient tables act like permanent but no fail-safe [OK]

Common Mistakes:

• Thinking transient tables cannot store data
• Expecting syntax error with TRANSIENT keyword
• Assuming transient tables auto-delete data immediately

4. You run the following command in Snowflake:

CREATE TEMPORARY TABLE temp_users (user_id INT, name STRING);

Later, you try to query temp_users in a new session but get an error. What is the most likely cause?

medium

A. Temporary tables only exist during the session they were created in

B. Syntax error in table creation

C. Transient tables cannot be queried

D. Table was dropped manually

Solution

1. Step 1: Recall temporary table lifecycle

   Temporary tables exist only for the duration of the session that created them.

2. Step 2: Understand session behavior

   Querying in a new session fails because the temporary table no longer exists.

3. Final Answer:

   Temporary tables only exist during the session they were created in -> Option A

4. Quick Check:

   Temporary = session-only lifespan [OK]

Hint: Temp tables vanish after session ends [OK]

Common Mistakes:

• Assuming temp tables persist across sessions
• Confusing transient with temporary tables
• Ignoring session scope of temporary tables

5. You want to create a table in Snowflake that stores temporary data across sessions but does not use fail-safe to reduce storage costs. Which table type and creation statement should you use?

hard

A. CREATE TRANSIENT TABLE cost_savings (id INT, amount NUMBER);

B. CREATE TEMPORARY TABLE cost_savings (id INT, amount NUMBER);

C. CREATE PERMANENT TABLE cost_savings (id INT, amount NUMBER);

D. CREATE EXTERNAL TABLE cost_savings (id INT, amount NUMBER);

Solution

1. Step 1: Identify table types and fail-safe behavior

   Transient tables do not have fail-safe, reducing storage costs but keep data beyond session.

2. Step 2: Match requirement with table type

   Temporary tables are session-only, permanent tables have fail-safe, external tables are for external data.

3. Final Answer:

   CREATE TRANSIENT TABLE cost_savings (id INT, amount NUMBER); -> Option A

4. Quick Check:

   Transient = no fail-safe, cost-saving [OK]

Hint: Use transient tables to save costs without fail-safe [OK]

Common Mistakes:

• Choosing temporary tables which expire after session
• Using permanent tables with fail-safe enabled
• Confusing external tables with transient