Time Travel retention periods in Snowflake - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Time Travel in Snowflake?

Time Travel lets you access historical data from a table or database as it existed at a past time or before a change happened.

beginner

What is the default Time Travel retention period for standard Snowflake accounts?

The default retention period is 1 day (24 hours) for standard accounts.

intermediate

What is the maximum Time Travel retention period available in Snowflake Enterprise Edition and above?

Up to 90 days of Time Travel retention is available in Enterprise Edition and higher.

intermediate

How does Time Travel retention period affect storage costs?

Longer retention periods keep more historical data, which increases storage usage and costs.

intermediate

Can you change the Time Travel retention period for a table after it is created?

Yes, you can alter the retention period for a table using SQL commands, within allowed limits based on your Snowflake edition.

What is the default Time Travel retention period for Snowflake standard accounts?

A 7 days

B 30 days

C 1 day

D 90 days

Standard Snowflake accounts have a default Time Travel retention period of 1 day (24 hours).

Which Snowflake edition supports up to 90 days of Time Travel retention?

A Standard Edition

B Enterprise Edition

C Free Trial

D Developer Edition

Enterprise Edition and above support up to 90 days of Time Travel retention.

What happens to storage costs when you increase the Time Travel retention period?

A Costs increase

B Costs stay the same

C Costs decrease

D Costs are refunded

Longer retention means more data is kept, which increases storage costs.

Can you access data from 10 days ago if your Time Travel retention is set to 7 days?

A Only if data was archived

B Yes, always

C Yes, but only with special permission

D No, only within retention period

You can only access historical data within the retention period set.

How do you change the Time Travel retention period for a table?

A Using ALTER TABLE command

B Using CREATE TABLE command

C Using DROP TABLE command

D Using SELECT command

You use ALTER TABLE to modify the retention period of an existing table.

Explain what Time Travel retention period means in Snowflake and why it matters.

Think about how long you can go back in time to see old data.

Describe how Snowflake editions affect the maximum Time Travel retention period available.

Different editions offer different time windows for Time Travel.

Practice

1. What does the Time Travel retention period in Snowflake control?

easy

A. How long you can access previous versions of data

B. How long data is stored in the cloud

C. The speed of query execution

D. The number of users who can access a table

Solution

1. Step 1: Understand Time Travel feature

   Time Travel allows you to see and restore past versions of your data.

2. Step 2: Identify what retention period controls

   The retention period sets how many days you can access these past versions.

3. Final Answer:

   How long you can access previous versions of data -> Option A

4. Quick Check:

   Retention period = access duration for past data [OK]

Hint: Retention period means how long past data is accessible [OK]

Common Mistakes:

• Confusing retention with storage duration
• Thinking it controls query speed
• Assuming it limits user access

2. Which SQL command correctly sets the Time Travel retention period to 7 days for a table named sales_data?

easy

A. ALTER TABLE sales_data SET RETENTION_DAYS = 7;

B. ALTER TABLE sales_data SET DATA_RETENTION_TIME_IN_DAYS = 7;

C. UPDATE TABLE sales_data SET DATA_RETENTION_TIME_IN_DAYS = 7;

D. ALTER TABLE sales_data DATA_RETENTION = 7;

Solution

1. Step 1: Recall correct syntax for setting retention

   The correct command uses ALTER TABLE with SET DATA_RETENTION_TIME_IN_DAYS.

2. Step 2: Match syntax with options

   ALTER TABLE sales_data SET DATA_RETENTION_TIME_IN_DAYS = 7; matches the exact syntax; others use incorrect keywords or commands.

3. Final Answer:

   ALTER TABLE sales_data SET DATA_RETENTION_TIME_IN_DAYS = 7; -> Option B

4. Quick Check:

   Use ALTER TABLE ... SET DATA_RETENTION_TIME_IN_DAYS [OK]

Hint: Use ALTER TABLE ... SET DATA_RETENTION_TIME_IN_DAYS [OK]

Common Mistakes:

• Using UPDATE instead of ALTER TABLE
• Wrong keyword like RETENTION_DAYS
• Missing SET keyword

3. Given a table with a Time Travel retention period of 3 days, what happens if you try to query data from 5 days ago using Time Travel?

medium

A. You get an error because data older than 3 days is not available

B. You get the data from 5 days ago without issues

C. The query runs but returns empty results

D. The retention period automatically extends to 5 days

Solution

1. Step 1: Understand retention period limit

   Retention period limits how far back you can access data versions.

2. Step 2: Apply to 5 days query with 3 days retention

   Since 5 days is beyond 3 days retention, data is unavailable and causes an error.

3. Final Answer:

   You get an error because data older than 3 days is not available -> Option A

4. Quick Check:

   Query beyond retention period = error [OK]

Hint: Cannot access data older than retention days [OK]

Common Mistakes:

• Assuming data is always available
• Thinking query returns empty instead of error
• Believing retention auto-extends

4. You tried to set the Time Travel retention period to 100 days on a table, but Snowflake returned an error. What is the most likely cause?

medium

A. You need to restart the Snowflake service

B. Syntax error in the ALTER TABLE command

C. Table does not support Time Travel

D. Retention period exceeds the maximum allowed limit

Solution

1. Step 1: Know Snowflake retention limits

   Snowflake limits Time Travel retention to a maximum (usually 1 to 90 days depending on edition).

2. Step 2: Check if 100 days exceeds limit

   100 days is beyond typical max, causing an error.

3. Final Answer:

   Retention period exceeds the maximum allowed limit -> Option D

4. Quick Check:

   Retention > max limit causes error [OK]

Hint: Check max retention days allowed before setting [OK]

Common Mistakes:

• Assuming syntax error without checking limits
• Thinking table lacks Time Travel support
• Believing service restart fixes retention errors

5. A company wants to keep Time Travel data for 14 days but minimize storage costs. Which approach best balances these needs?

hard

A. Set DATA_RETENTION_TIME_IN_DAYS to 30 to avoid data loss

B. Set DATA_RETENTION_TIME_IN_DAYS to 1 and rely on backups for older data

C. Set DATA_RETENTION_TIME_IN_DAYS to 14 and regularly purge old data

D. Disable Time Travel and keep manual snapshots

Solution

1. Step 1: Understand retention vs storage cost

   Longer retention means more storage cost; shorter retention saves cost but limits recovery.

2. Step 2: Evaluate options for 14-day retention and cost balance

   Setting retention to 14 days meets recovery needs; purging old data helps control storage.

3. Final Answer:

   Set DATA_RETENTION_TIME_IN_DAYS to 14 and regularly purge old data -> Option C

4. Quick Check:

   Retention matches need + purge controls cost [OK]

Hint: Match retention days to need, purge to save cost [OK]

Common Mistakes:

• Setting retention too low losing data
• Setting retention too high increasing cost
• Disabling Time Travel losing recovery benefits