Result caching layers in Snowflake - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is result caching in Snowflake?

Result caching in Snowflake stores the results of a query so that if the same query is run again, Snowflake can return the stored results instantly without re-executing the query.

beginner

How long does Snowflake keep query results in the result cache?

Snowflake keeps query results in the result cache for 24 hours, as long as the underlying data has not changed.

intermediate

What conditions must be met for Snowflake to use the result cache for a query?

The query text must be exactly the same, the underlying data must not have changed, and the user must have the same access rights.

beginner

What is the benefit of result caching in Snowflake?

It reduces query execution time and saves compute resources by returning stored results instantly instead of running the query again.

intermediate

Can result caching be disabled in Snowflake?

Yes, result caching can be disabled by setting the parameter USE_CACHED_RESULT to FALSE in the query.

How long does Snowflake keep query results in the result cache?

A 7 days

B 1 hour

C 24 hours

D Until the warehouse is restarted

Snowflake keeps query results in the result cache for 24 hours if the underlying data remains unchanged.

Which of the following is NOT a requirement for Snowflake to use the result cache?

A Underlying data must not have changed

B Warehouse must be running on the same server

C User must have the same access rights

D Query text must be exactly the same

Snowflake's result cache is independent of the warehouse server location.

What happens if the underlying data changes after a query is cached?

A Snowflake ignores the cache and reruns the query

B Snowflake returns the cached result anyway

C Snowflake deletes the cache but returns old results

D Snowflake pauses the query

If data changes, Snowflake invalidates the cache and reruns the query to get fresh results.

How can you disable result caching for a specific query in Snowflake?

A Set USE_CACHED_RESULT = FALSE

B Set CACHE_ENABLED = FALSE

C Use NO_CACHE keyword

D Result caching cannot be disabled

You can disable result caching by setting USE_CACHED_RESULT = FALSE in the query.

What is the main benefit of using result caching in Snowflake?

A Automatically backs up data

B Increases storage space

C Allows multiple users to edit data simultaneously

D Improves query speed and saves compute resources

Result caching speeds up queries and reduces compute costs by reusing previous results.

Explain how Snowflake's result caching works and when it is used.

Think about what must stay the same for cache to be used.

Describe how to disable result caching for a query in Snowflake and why you might want to do that.

Consider scenarios needing fresh data always.

Practice

1. What does Snowflake's result caching do when you run the same query multiple times within 24 hours?

easy

A. Deletes the previous result and returns an error

B. Runs the query again and stores a new result

C. Requires manual cache refresh before returning results

D. Returns the cached result instantly without rerunning the query

Solution

1. Step 1: Understand Snowflake's caching behavior

   Snowflake stores query results for 24 hours to speed up repeated queries.

2. Step 2: Identify the effect of caching on repeated queries

   When the same query runs again within 24 hours, Snowflake returns the cached result instantly without rerunning the query.

3. Final Answer:

   Returns the cached result instantly without rerunning the query -> Option D

4. Quick Check:

   Result caching = instant cached return [OK]

Hint: Same query within 24h returns cached result instantly [OK]

Common Mistakes:

• Thinking query always reruns
• Assuming cache expires immediately
• Believing manual refresh is needed

2. Which of the following is the correct way to disable result caching for a single query in Snowflake?

easy

A. ALTER SESSION SET DISABLE_CACHE = TRUE;

B. ALTER SESSION SET USE_CACHED_RESULT = FALSE;

C. ALTER SESSION SET NO_CACHE_RESULT = TRUE;

D. ALTER SESSION SET SKIP_CACHE = TRUE;

Solution

1. Step 1: Recall how to disable result caching

   Snowflake uses ALTER SESSION SET USE_CACHED_RESULT = FALSE to disable caching for the session.

2. Step 2: Match the correct syntax

   The correct syntax is ALTER SESSION SET USE_CACHED_RESULT = FALSE;

3. Final Answer:

   ALTER SESSION SET USE_CACHED_RESULT = FALSE; -> Option B

4. Quick Check:

   Disable cache param = USE_CACHED_RESULT = FALSE [OK]

Hint: Use ALTER SESSION SET USE_CACHED_RESULT = FALSE to disable caching [OK]

Common Mistakes:

• Using wrong parameter names
• Incorrect ALTER SESSION syntax
• Confusing with other cache parameters

3. Consider this sequence of queries run in Snowflake:
SELECT COUNT(*) FROM sales;
Immediately followed by:
SELECT COUNT(*) FROM sales;
What will happen on the second query?

medium

A. Snowflake returns the cached result from the first query

B. Snowflake returns partial results from cache

C. Snowflake returns an error about duplicate queries

D. Snowflake reruns the query and returns fresh results

Solution

1. Step 1: Identify caching behavior for repeated queries

   Snowflake caches query results for 24 hours and returns cached results if the same query runs again.

2. Step 2: Apply to the given queries

   The second SELECT COUNT(*) query is identical and runs immediately, so Snowflake returns the cached result.

3. Final Answer:

   Snowflake returns the cached result from the first query -> Option A

4. Quick Check:

   Repeated query = cached result return [OK]

Hint: Repeated query returns cached result instantly [OK]

Common Mistakes:

• Assuming query always reruns
• Expecting partial or error results
• Confusing cache with data freshness

4. You executed this command in Snowflake:
ALTER SESSION SET USE_CACHED_RESUTL = FALSE;
But you notice subsequent queries still return cached results. What is the likely cause?

medium

A. Result caching cannot be disabled in Snowflake

B. The query is too complex to cache

C. The USE_CACHED_RESULT parameter is misspelled or incorrect

D. The cache expired before the query ran

Solution

1. Step 1: Verify the USE_CACHED_RESULT parameter usage

   The parameter must be spelled exactly USE_CACHED_RESULT and set to FALSE to disable caching.

2. Step 2: Identify why caching still happens

   If caching still occurs, the parameter might be misspelled or incorrectly specified.

3. Final Answer:

   The USE_CACHED_RESULT parameter is misspelled or incorrect -> Option C

4. Quick Check:

   Correct parameter spelling and value disables cache [OK]

Hint: Check parameter spelling and syntax to disable caching [OK]

Common Mistakes:

• Assuming caching can't be disabled
• Misspelling the parameter name
• Ignoring exact parameter syntax

5. You want to ensure a query always returns fresh data and never uses cached results in Snowflake. Which approach correctly achieves this while minimizing cost?

hard

A. Execute ALTER SESSION SET USE_CACHED_RESULT = FALSE; before the query to disable caching

B. Manually clear the entire result cache before running the query

C. Run the query multiple times to refresh the cache

D. Use a different warehouse to bypass caching

Solution

1. Step 1: Identify how to disable result caching per session

   Snowflake allows disabling result caching using ALTER SESSION SET USE_CACHED_RESULT = FALSE before the query.

2. Step 2: Evaluate other options for cost and effectiveness

   Manually clearing cache or switching warehouses is inefficient and costly; running multiple times does not guarantee fresh data.

3. Final Answer:

   Execute ALTER SESSION SET USE_CACHED_RESULT = FALSE; before the query to disable caching -> Option A

4. Quick Check:

   Use USE_CACHED_RESULT = FALSE for fresh data [OK]

Hint: Use ALTER SESSION SET USE_CACHED_RESULT = FALSE for fresh data without extra cost [OK]

Common Mistakes:

• Trying to clear cache manually
• Switching warehouses unnecessarily
• Relying on repeated runs to refresh data