Data lineage tracking in Snowflake - Mini Project: Build & Apply

Data Lineage Tracking in Snowflake

📖 Scenario: You work as a data engineer in a company that uses Snowflake for data warehousing. Your team wants to track the flow of data between tables to understand where data comes from and where it goes. This helps in debugging and auditing data pipelines.

🎯 Goal: Build a simple data lineage tracking setup in Snowflake by creating tables, adding a configuration variable, writing a query to capture lineage, and finally creating a view to show the lineage.

📋 What You'll Learn

Create a source table with sample data

Create a target table to receive data

Add a configuration variable to hold the current timestamp

Write a query to insert data from source to target while capturing lineage

Create a view that shows the lineage information

💡 Why This Matters

🌍 Real World

Tracking data lineage helps companies understand data flow, troubleshoot issues, and comply with regulations.

💼 Career

Data engineers and analysts use lineage tracking to maintain data quality and transparency in data pipelines.

1

Create source and target tables

Create a table called source_data with columns id INT and value STRING. Insert three rows with ids 1, 2, 3 and values 'A', 'B', 'C'. Then create an empty table called target_data with the same columns.

Snowflake

-- Create source_data table and insert rows
-- Create target_data table

Hint

Use CREATE OR REPLACE TABLE to create tables and INSERT INTO to add rows.

2

Add a configuration variable for timestamp

Create a variable called current_time and set it to the current timestamp using CURRENT_TIMESTAMP().

Snowflake

CREATE OR REPLACE TABLE source_data (id INT, value STRING);
INSERT INTO source_data (id, value) VALUES (1, 'A'), (2, 'B'), (3, 'C');
CREATE OR REPLACE TABLE target_data (id INT, value STRING);
-- Create variable current_time with CURRENT_TIMESTAMP()

Hint

Use SET variable_name = value; to create a variable in Snowflake.

3

Insert data with lineage tracking

Insert data from source_data into target_data. Add a new column load_time to target_data to store the value of current_time for lineage tracking. Alter target_data to add load_time TIMESTAMP before inserting.

Snowflake

CREATE OR REPLACE TABLE source_data (id INT, value STRING);
INSERT INTO source_data (id, value) VALUES (1, 'A'), (2, 'B'), (3, 'C');
CREATE OR REPLACE TABLE target_data (id INT, value STRING);
SET current_time = CURRENT_TIMESTAMP();
-- Alter target_data to add load_time column
-- Insert data from source_data into target_data with load_time

Hint

Use ALTER TABLE to add a column. Use INSERT INTO ... SELECT ... to copy data with the timestamp.

4

Create a view to show data lineage

Create a view called data_lineage_view that selects id, value, and load_time from target_data to show the lineage information.

Snowflake

CREATE OR REPLACE TABLE source_data (id INT, value STRING);
INSERT INTO source_data (id, value) VALUES (1, 'A'), (2, 'B'), (3, 'C');
CREATE OR REPLACE TABLE target_data (id INT, value STRING);
SET current_time = CURRENT_TIMESTAMP();
ALTER TABLE target_data ADD COLUMN load_time TIMESTAMP;
INSERT INTO target_data (id, value, load_time) SELECT id, value, $current_time FROM source_data;
-- Create view data_lineage_view selecting id, value, load_time from target_data

Hint

Use CREATE OR REPLACE VIEW view_name AS SELECT ... to create the view.

Practice

1. What is the main purpose of data lineage tracking in Snowflake?

easy

A. To increase storage capacity automatically

B. To show where data comes from and how it moves

C. To encrypt data at rest

D. To create user accounts

Solution

1. Step 1: Understand data lineage concept

   Data lineage tracks the origin and flow of data through systems.

2. Step 2: Match with Snowflake purpose

   Snowflake uses lineage to show data source and movement, not storage or encryption.

3. Final Answer:

   To show where data comes from and how it moves -> Option B

4. Quick Check:

   Data lineage = data origin and flow [OK]

Hint: Data lineage means tracking data origin and flow [OK]

Common Mistakes:

• Confusing lineage with storage management
• Thinking lineage is about encryption
• Mixing lineage with user management

2. Which Snowflake command helps you explore data lineage by showing object dependencies?

easy

A. SHOW OBJECT DEPENDENCIES

B. SHOW USERS

C. DESCRIBE TABLE

D. CREATE WAREHOUSE

Solution

1. Step 1: Identify command for lineage

   SHOW OBJECT DEPENDENCIES lists how objects depend on each other, revealing lineage.

2. Step 2: Eliminate unrelated commands

   SHOW USERS lists users, DESCRIBE TABLE shows table structure, CREATE WAREHOUSE creates compute resources.

3. Final Answer:

   SHOW OBJECT DEPENDENCIES -> Option A

4. Quick Check:

   Lineage command = SHOW OBJECT DEPENDENCIES [OK]

Hint: Use SHOW OBJECT DEPENDENCIES to see lineage [OK]

Common Mistakes:

• Using SHOW USERS for lineage
• Confusing DESCRIBE TABLE with lineage
• Thinking CREATE WAREHOUSE shows dependencies

3. Given the following Snowflake query:

SHOW OBJECT DEPENDENCIES LIKE 'SALES_DATA';

What does this query return?

medium

A. List of users who accessed SALES_DATA

B. List of warehouses running SALES_DATA queries

C. List of tables with similar names to SALES_DATA

D. List of objects that depend on or are used by SALES_DATA

Solution

1. Step 1: Understand SHOW OBJECT DEPENDENCIES usage

   This command shows dependencies related to the specified object, here SALES_DATA.

2. Step 2: Interpret LIKE filter

   LIKE 'SALES_DATA' filters to objects named SALES_DATA, showing their dependencies.

3. Final Answer:

   List of objects that depend on or are used by SALES_DATA -> Option D

4. Quick Check:

   SHOW OBJECT DEPENDENCIES LIKE = dependency list [OK]

Hint: SHOW OBJECT DEPENDENCIES lists related objects [OK]

Common Mistakes:

• Thinking it shows user access logs
• Confusing with warehouse usage
• Assuming it lists similar table names

4. You run SHOW OBJECT DEPENDENCIES LIKE 'CUSTOMER_ORDERS'; but get no results. What is a likely reason?

medium

A. The object name is misspelled or does not exist

B. You need to create a warehouse first

C. SHOW OBJECT DEPENDENCIES does not work on tables

D. Your user lacks SELECT permission on CUSTOMER_ORDERS

Solution

1. Step 1: Check object existence

   No results usually mean the object name is wrong or missing in the database.

2. Step 2: Verify command applicability and permissions

   SHOW OBJECT DEPENDENCIES works on tables; warehouse creation is unrelated; lack of SELECT permission does not hide dependencies.

3. Final Answer:

   The object name is misspelled or does not exist -> Option A

4. Quick Check:

   No results = wrong or missing object name [OK]

Hint: Check spelling and existence if no dependencies show [OK]

Common Mistakes:

• Assuming warehouse needed for lineage
• Thinking permissions block SHOW OBJECT DEPENDENCIES
• Believing tables can't have dependencies

5. You want to track data lineage for a complex pipeline involving multiple views and tables in Snowflake. Which approach best ensures accurate lineage tracking?

hard

A. Only track lineage for base tables, ignoring views

B. Manually document dependencies in a spreadsheet

C. Use SHOW OBJECT DEPENDENCIES and automate lineage extraction with Snowflake metadata queries

D. Rely on user memory to recall data flow

Solution

1. Step 1: Understand lineage complexity

   Complex pipelines need automated, accurate tracking to avoid errors and omissions.

2. Step 2: Evaluate options for accuracy and scalability

   Manual docs and memory are error-prone; ignoring views misses dependencies; using SHOW OBJECT DEPENDENCIES with automation is best practice.

3. Final Answer:

   Use SHOW OBJECT DEPENDENCIES and automate lineage extraction with Snowflake metadata queries -> Option C

4. Quick Check:

   Automate lineage with SHOW OBJECT DEPENDENCIES for accuracy [OK]

Hint: Automate lineage extraction using SHOW OBJECT DEPENDENCIES [OK]

Common Mistakes:

• Relying on manual documentation only
• Ignoring views in lineage tracking
• Trusting memory instead of tools