Warehouse selection strategies in Snowflake - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a warehouse in Snowflake?

A warehouse in Snowflake is a cluster of compute resources used to perform data processing tasks like queries and loading data.

beginner

Why choose a larger warehouse size in Snowflake?

A larger warehouse size provides more compute power, which can speed up query processing but costs more credits.

intermediate

What is the benefit of using multi-cluster warehouses?

Multi-cluster warehouses automatically add or remove clusters to handle varying workloads, improving concurrency without manual intervention.

beginner

How does auto-suspend help in warehouse selection?

Auto-suspend pauses the warehouse after inactivity, saving costs by not running compute resources when not needed.

intermediate

What factors influence the choice of warehouse for a query?

Factors include query complexity, concurrency needs, cost considerations, and workload patterns.

What does a larger Snowflake warehouse size provide?

A More compute power

B More storage space

C Longer query times

D Lower cost

A larger warehouse size means more compute resources, which speeds up queries.

What is the main advantage of multi-cluster warehouses?

A Slower query processing

B Reduced storage costs

C Manual cluster management

D Automatic scaling for concurrency

Multi-cluster warehouses add or remove clusters automatically to handle many users.

What does auto-suspend do in Snowflake warehouses?

A Increases warehouse size

B Deletes warehouse data

C Pauses warehouse after inactivity

D Starts warehouse automatically

Auto-suspend saves cost by pausing compute when not in use.

Which factor is NOT important when selecting a warehouse?

A Color of the warehouse icon

B Concurrency needs

C Cost considerations

D Query complexity

The icon color has no impact on warehouse performance or cost.

What happens if you choose a warehouse too small for your workload?

A Costs will be higher

B Queries may run slower

C Warehouse will auto-scale to larger size

D Data will be lost

A small warehouse may not have enough compute power, causing slower queries.

Explain how Snowflake warehouse size and multi-cluster options affect query performance and cost.

Think about how compute resources and concurrency affect query speed and billing.

Describe the role of auto-suspend and auto-resume in warehouse cost management.

Consider how pausing and starting compute resources affects billing.

Practice

1. What does the USE WAREHOUSE command do in Snowflake?

easy

A. It lists all available warehouses.

B. It switches the current warehouse to run queries.

C. It deletes an existing warehouse.

D. It creates a new warehouse.

Solution

1. Step 1: Understand the purpose of USE WAREHOUSE

   This command changes which warehouse is active for running queries.

2. Step 2: Compare with other commands

   Creating, deleting, or listing warehouses use different commands, not USE WAREHOUSE.

3. Final Answer:

   It switches the current warehouse to run queries. -> Option B

4. Quick Check:

   USE WAREHOUSE changes active warehouse [OK]

Hint: Remember: USE means switch active warehouse [OK]

Common Mistakes:

• Confusing USE with CREATE or DROP commands
• Thinking it lists warehouses
• Assuming it modifies warehouse size

2. Which of the following is the correct syntax to switch to a warehouse named COMPUTE_WH?

easy

A. USE WAREHOUSE COMPUTE_WH;

B. SWITCH WAREHOUSE COMPUTE_WH;

C. SELECT WAREHOUSE COMPUTE_WH;

D. CHANGE WAREHOUSE TO COMPUTE_WH;

Solution

1. Step 1: Recall the correct command syntax

   The command to switch warehouses is USE WAREHOUSE <name>;.

2. Step 2: Check each option

   Only USE WAREHOUSE COMPUTE_WH; matches the correct syntax exactly.

3. Final Answer:

   USE WAREHOUSE COMPUTE_WH; -> Option A

4. Quick Check:

   Correct syntax = USE WAREHOUSE [name]; [OK]

Hint: USE WAREHOUSE plus name switches warehouse [OK]

Common Mistakes:

• Using SWITCH or CHANGE instead of USE
• Adding extra keywords like TO or SELECT
• Missing semicolon at end

3. Given the following commands run in order:

USE WAREHOUSE SMALL_WH;
SELECT CURRENT_WAREHOUSE();
USE WAREHOUSE LARGE_WH;
SELECT CURRENT_WAREHOUSE();

What will be the output of the two CURRENT_WAREHOUSE() calls?

medium

A. SMALL_WH then LARGE_WH

B. LARGE_WH then SMALL_WH

C. SMALL_WH twice

D. LARGE_WH twice

Solution

1. Step 1: Analyze the first USE WAREHOUSE command

   The first command sets the active warehouse to SMALL_WH, so the first CURRENT_WAREHOUSE() returns SMALL_WH.

2. Step 2: Analyze the second USE WAREHOUSE command

   The second command switches the active warehouse to LARGE_WH, so the second CURRENT_WAREHOUSE() returns LARGE_WH.

3. Final Answer:

   SMALL_WH then LARGE_WH -> Option A

4. Quick Check:

   Warehouse switches reflect in CURRENT_WAREHOUSE() [OK]

Hint: Each USE WAREHOUSE changes current warehouse immediately [OK]

Common Mistakes:

• Assuming warehouse does not change after second USE
• Mixing order of outputs
• Thinking CURRENT_WAREHOUSE() returns session name

4. You run the command USE WAREHOUSE BIG_WH but get an error saying the warehouse does not exist. What is the most likely cause?

medium

A. The command requires a semicolon at the end.

B. You need to restart your Snowflake session.

C. You must create a database before switching warehouses.

D. The warehouse name is misspelled or does not exist.

Solution

1. Step 1: Understand the error message

   The error says the warehouse does not exist, so the name is likely wrong or missing.

2. Step 2: Evaluate other options

   Restarting session or creating a database is unrelated; semicolon missing usually causes syntax error, not 'does not exist'.

3. Final Answer:

   The warehouse name is misspelled or does not exist. -> Option D

4. Quick Check:

   Nonexistent warehouse name causes error [OK]

Hint: Check warehouse name spelling if 'does not exist' error appears [OK]

Common Mistakes:

• Restarting session unnecessarily
• Confusing warehouse with database
• Ignoring error message details

5. You have two warehouses: SMALL_WH with 1 cluster and LARGE_WH with 4 clusters. You want to run a heavy query quickly but also save costs on light queries. Which strategy is best?

hard

A. Always use LARGE_WH for all queries to ensure speed.

B. Use SMALL_WH only and increase its size when needed.

C. Use SMALL_WH for light queries and switch to LARGE_WH for heavy queries.

D. Create a new warehouse for each query type.

Solution

1. Step 1: Understand warehouse sizes and costs

   SMALL_WH is cheaper and good for light work; LARGE_WH is bigger and faster but costs more.

2. Step 2: Choose strategy balancing speed and cost

   Switching warehouses based on query load saves cost and improves performance.

3. Final Answer:

   Use SMALL_WH for light queries and switch to LARGE_WH for heavy queries. -> Option C

4. Quick Check:

   Match warehouse size to query load for cost and speed [OK]

Hint: Match warehouse size to query weight, switch as needed [OK]

Common Mistakes:

• Using large warehouse always wastes cost
• Trying to resize warehouses dynamically
• Creating many warehouses unnecessarily