Time Travel retention periods in Snowflake - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the Time Travel retention period to 7 days for a Snowflake table.

Snowflake

ALTER TABLE my_table SET DATA_RETENTION_TIME_IN_DAYS = [1];

Drag options to blanks, or click blank then click option'

A7

B30

C0

D90

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 disables Time Travel.

Setting too high a value may increase storage costs.

Setting DATA_RETENTION_TIME_IN_DAYS to 7 enables Time Travel for 7 days.

2fill in blank

medium

Complete the code to query the current Time Travel retention period for a Snowflake table.

Snowflake

SHOW TABLES LIKE 'my_table'; -- Look for retention_time in the [1] column

Drag options to blanks, or click blank then click option'

Aname

Bcreated_on

Cretention_time

Downer

Attempts:

3 left

💡 Hint

Common Mistakes

Checking unrelated columns like owner or created_on.

Assuming retention period is in a different table property.

The retention_time column shows the Time Travel retention period.

3fill in blank

hard

Fix the error in the command to disable Time Travel on a Snowflake table.

Snowflake

ALTER TABLE my_table SET DATA_RETENTION_TIME_IN_DAYS = [1];

Drag options to blanks, or click blank then click option'

A0

B-1

CNULL

DFALSE

Attempts:

3 left

💡 Hint

Common Mistakes

Using NULL or negative numbers causes errors.

Using boolean values like FALSE is invalid.

Setting DATA_RETENTION_TIME_IN_DAYS to 0 disables Time Travel.

4fill in blank

hard

Fill both blanks to set Time Travel retention to 1 day and clone the table.

Snowflake

ALTER TABLE my_table SET DATA_RETENTION_TIME_IN_DAYS = [1];
CREATE TABLE my_table_clone CLONE my_table [2] (TIMESTAMP => CURRENT_TIMESTAMP());

Drag options to blanks, or click blank then click option'

A1

BAFTER

CAT

DBEFORE

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong keywords like AFTER or BEFORE for cloning.

Setting retention to invalid values.

Retention is set to 1 day. Cloning uses AT to specify the time for the clone.

5fill in blank

hard

Fill all three blanks to query the history of a table within its Time Travel retention period.

Snowflake

SELECT * FROM my_table [1] ([2] => CURRENT_TIMESTAMP - INTERVAL '[3] DAY');

Drag options to blanks, or click blank then click option'

AAT

BTIMESTAMP

C7

DBEFORE

Attempts:

3 left

💡 Hint

Common Mistakes

Using AT instead of BEFORE for historical queries.

Incorrect interval values or syntax.

Use BEFORE with TIMESTAMP to query data as it was 7 days ago.

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