Why Snowflake separates compute from storage - Performance Analysis

Time Complexity: Why Snowflake separates compute from storage

O(n / c)

Understanding Time Complexity

We want to understand how Snowflake's design of separating compute from storage affects the time it takes to run queries.

Specifically, how does the number of compute resources and data size impact execution time?

Scenario Under Consideration

Analyze the time complexity of querying data in Snowflake with separate compute and storage.

-- Create a warehouse (compute)
CREATE WAREHOUSE my_wh WITH WAREHOUSE_SIZE = 'XSMALL';

-- Query data from a large table stored separately
SELECT * FROM big_table WHERE condition = 'value';

-- Scale warehouse size to increase compute power
ALTER WAREHOUSE my_wh SET WAREHOUSE_SIZE = 'LARGE';

-- Run the same query again
SELECT * FROM big_table WHERE condition = 'value';

This sequence shows how compute resources can be adjusted independently from storage to affect query time.

Identify Repeating Operations

Look at what happens repeatedly when running queries.

• Primary operation: Query execution using compute warehouse accessing stored data.
• How many times: Each query runs once, but compute resources can be scaled multiple times.

How Execution Grows With Input

As data size grows, the amount of data to scan grows too, increasing query time.

Input Size (n)	Approx. Compute Operations
10 GB	Small number of compute operations, fast query
100 GB	More compute operations, longer query time
1 TB	Much more compute operations, much longer query time

Increasing compute size can reduce time, but data scanned still grows with input size.

Final Time Complexity

Time Complexity: O(n / c)

This means query time grows with data size n, but dividing by compute power c reduces time.

Common Mistake

[X] Wrong: "Adding more compute always makes queries instant regardless of data size."

[OK] Correct: More compute helps, but scanning large data still takes time; compute can't make data size zero.

Interview Connect

Understanding how compute and storage separation affects query time shows you can balance resources for cost and speed, a key cloud skill.

Self-Check

"What if Snowflake did not separate compute from storage? How would that change the time complexity of queries?"

Practice

1. Why does Snowflake separate compute from storage?

easy

A. To combine compute and storage for faster processing

B. To store data only on local machines

C. To allow independent scaling of compute and storage resources

D. To limit the number of users accessing data

Solution

1. Step 1: Understand Snowflake's architecture

   Snowflake separates compute (processing power) and storage (data saved) so they can work independently.

2. Step 2: Identify the benefit of separation

   This separation allows users to scale compute resources up or down without affecting stored data, improving flexibility and cost.

3. Final Answer:

   To allow independent scaling of compute and storage resources -> Option C

4. Quick Check:

   Separation means independent scaling = A [OK]

Hint: Think: compute and storage can grow separately [OK]

Common Mistakes:

• Confusing separation with combining compute and storage
• Thinking data is stored only locally
• Believing separation limits user access

2. Which of the following is the correct way to describe Snowflake's compute and storage separation?

easy

A. Compute resources can be paused without affecting stored data

B. Storage automatically scales with compute usage

C. Compute and storage are tightly coupled in one system

D. Compute and storage must always scale together

Solution

1. Step 1: Review compute and storage behavior

   Snowflake allows compute (warehouses) to be paused or resized without impacting stored data.

2. Step 2: Match the correct description

   Compute resources can be paused without affecting stored data correctly states compute can be paused independently, which is a key feature.

3. Final Answer:

   Compute resources can be paused without affecting stored data -> Option A

4. Quick Check:

   Compute pause independent of storage = C [OK]

Hint: Remember: compute can pause, storage stays safe [OK]

Common Mistakes:

• Thinking compute and storage are tightly linked
• Assuming storage scales automatically with compute
• Believing compute and storage must scale together

3. Consider this scenario: You run multiple queries on Snowflake using different virtual warehouses. What is the main advantage of Snowflake's compute-storage separation in this case?

medium

A. Queries run slower because compute and storage are separate

B. Each warehouse can scale independently without data duplication

C. Data must be copied for each warehouse to run queries

D. Storage costs increase with each warehouse

Solution

1. Step 1: Analyze multiple warehouses running queries

   Snowflake allows multiple compute clusters (warehouses) to access the same storage without copying data.

2. Step 2: Understand the benefit of independent scaling

   Each warehouse can scale or pause independently, improving performance and cost without duplicating data.

3. Final Answer:

   Each warehouse can scale independently without data duplication -> Option B

4. Quick Check:

   Independent scaling, no data copy = D [OK]

Hint: Multiple warehouses share storage, no copies needed [OK]

Common Mistakes:

• Assuming data is copied for each warehouse
• Thinking compute-storage separation slows queries
• Believing storage costs rise with more warehouses

4. You notice your Snowflake compute warehouse is running slowly. You try to scale up compute but the performance does not improve. What could be a reason related to compute-storage separation?

medium

A. Compute and storage must be scaled together to improve speed

B. Compute warehouses cannot be resized after creation

C. Scaling compute automatically scales storage too

D. Storage is the bottleneck, not compute, since they are separate

Solution

1. Step 1: Understand compute-storage bottlenecks

   Since compute and storage are separate, scaling compute won't help if storage speed limits performance.

2. Step 2: Identify the correct reason

   Storage is the bottleneck, not compute, since they are separate correctly points out storage could be the bottleneck even if compute is scaled.

3. Final Answer:

   Storage is the bottleneck, not compute, since they are separate -> Option D

4. Quick Check:

   Separate storage bottleneck limits speed = B [OK]

Hint: Slow queries? Check storage bottleneck, not just compute [OK]

Common Mistakes:

• Assuming compute and storage scale together
• Believing compute cannot be resized
• Thinking scaling compute always fixes performance

5. You want to optimize costs and performance in Snowflake by using multiple virtual warehouses for different teams. How does Snowflake's separation of compute and storage help you achieve this?

hard

A. You can pause or resize warehouses independently while sharing the same data storage

B. You must create separate copies of data for each warehouse to avoid conflicts

C. Storage costs increase with each warehouse you create

D. Compute and storage are combined, so scaling one scales the other automatically

Solution

1. Step 1: Understand cost and performance optimization

   Using multiple warehouses allows teams to work independently without interfering with each other.

2. Step 2: Apply compute-storage separation benefits

   Since compute and storage are separate, warehouses can be paused or resized independently while sharing the same data, saving costs.

3. Final Answer:

   You can pause or resize warehouses independently while sharing the same data storage -> Option A

4. Quick Check:

   Independent warehouse control with shared storage = A [OK]

Hint: Pause or resize warehouses without copying data [OK]

Common Mistakes:

• Thinking data must be copied for each warehouse
• Assuming storage costs rise with more warehouses
• Believing compute and storage always scale together