Result caching layers in Snowflake - Commands & Configuration

Introduction

When you run queries in Snowflake, it can save the results so it doesn't have to do the same work again. This saves time and computing power by using cached results instead of re-running the full query.

When you run the same query multiple times and want faster results.

When you want to reduce the cost of repeated data analysis.

When you have dashboards that refresh often but the underlying data does not change.

When you want to improve performance for reports used by many users.

When you want to avoid unnecessary load on your Snowflake warehouse.

Commands

Run a simple query to check the current time and see if result caching is working by running it again quickly.

Terminal

SELECT CURRENT_TIMESTAMP();

Expected Output

CURRENT_TIMESTAMP()

2024-06-01 12:00:00.000

Run the same query again immediately to get the result from cache, which is faster and uses less compute.

Terminal

SELECT CURRENT_TIMESTAMP();

Expected Output

CURRENT_TIMESTAMP()

2024-06-01 12:00:00.000

Check how much result caching Snowflake has used recently to confirm caching is active.

Terminal

SELECT SYSTEM$RESULT_CACHE_USAGE();

Expected Output

RESULT_CACHE_HITS

1

Turn off result caching for the session to force queries to run fresh, useful for testing or when you want the latest data.

Terminal

ALTER SESSION SET USE_CACHED_RESULT = FALSE;

Expected Output

No output (command runs silently)

Run the query again with caching turned off to see the fresh result and confirm caching is disabled.

Terminal

SELECT CURRENT_TIMESTAMP();

Expected Output

CURRENT_TIMESTAMP()

2024-06-01 12:00:01.500

Key Concept

If you remember nothing else from this pattern, remember: Snowflake saves query results automatically and reuses them to speed up repeated queries without extra cost.

Common Mistakes

Expecting result caching to work when the underlying data has changed.

Snowflake invalidates cached results if the data changes, so the cache won't be used and the query runs fresh.

Understand that result caching only works when data and query text are unchanged.

Turning off caching globally without knowing it increases compute costs.

Disabling caching causes all queries to run fully every time, which uses more resources and costs more.

Disable caching only when necessary, like for testing or debugging.

Summary

Run a query once to store its result in Snowflake's cache.

Run the same query again to get fast results from the cache without extra compute.

Use session settings to enable or disable caching as needed for fresh data or testing.

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