Database migration testing in Testing Fundamentals - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is database migration testing?

Database migration testing is the process of verifying that data is correctly moved from one database to another without loss or corruption.

beginner

Why is data validation important in database migration testing?

Data validation ensures that the data in the new database matches the original data exactly, preventing errors and data loss.

intermediate

Name two common types of database migration testing.

1. Schema migration testing - checks if database structure is correctly migrated.
2. Data migration testing - checks if data is accurately transferred.

intermediate

What is a good way to check data integrity after migration?

Compare row counts, run checksum or hash functions on tables, and verify key data fields between old and new databases.

beginner

What could cause migration testing to fail?

Possible causes include data loss, mismatched data types, missing tables or columns, and incorrect data transformations.

What is the main goal of database migration testing?

A To improve database speed

B To ensure data is moved correctly without loss

C To create new database tables

D To delete old data

The main goal is to verify that data is transferred correctly and completely.

Which of the following is NOT a focus of database migration testing?

A Data accuracy

B Schema correctness

C User interface design

D Data integrity

User interface design is unrelated to database migration testing.

What method can help verify data integrity after migration?

A Running checksum comparisons

B Changing database passwords

C Deleting old tables

D Adding new columns

Checksum comparisons help confirm data has not changed during migration.

Which problem might cause migration testing to fail?

A Backing up data

B Using a faster network

C Adding indexes

D Data loss during transfer

Data loss is a critical failure in migration testing.

Schema migration testing checks for:

A Correct database structure

B Data accuracy

C User permissions

D Network speed

Schema migration testing ensures the database structure is correctly moved.

Explain the key steps involved in database migration testing.

Think about what you do before, during, and after moving data.

Describe common challenges faced during database migration testing and how to address them.

Consider what can go wrong and how testers check for problems.

Practice

1. What is the main goal of database migration testing?

easy

A. To redesign the database schema

B. To check the speed of the new database server

C. To verify that data is correctly and completely moved from the old database to the new one

D. To backup the database before migration

Solution

1. Step 1: Understand the purpose of migration testing

   Migration testing focuses on ensuring data integrity and completeness after moving data.

2. Step 2: Identify the main goal

   The main goal is to verify data correctness and completeness in the new database.

3. Final Answer:

   To verify that data is correctly and completely moved from the old database to the new one -> Option C

4. Quick Check:

   Migration testing = Data correctness and completeness [OK]

Hint: Focus on data correctness and completeness in migration [OK]

Common Mistakes:

• Confusing migration testing with performance testing
• Thinking migration testing is about database design
• Assuming backup is the main goal

2. Which of the following is the correct SQL query to count rows in a table named users for migration testing?

easy

A. SELECT COUNT(*) FROM users;

B. SELECT COUNT FROM users;

C. COUNT FROM users;

D. SELECT * FROM users COUNT;

Solution

1. Step 1: Recall correct SQL syntax for counting rows

   The correct syntax uses SELECT COUNT(*) FROM table_name;

2. Step 2: Match options with correct syntax

   SELECT COUNT(*) FROM users; matches the correct syntax exactly.

3. Final Answer:

   SELECT COUNT(*) FROM users; -> Option A

4. Quick Check:

   Count rows = SELECT COUNT(*) FROM table [OK]

Hint: Use SELECT COUNT(*) FROM table_name; for row counts [OK]

Common Mistakes:

• Using COUNT without SELECT
• Placing COUNT after * incorrectly
• Omitting parentheses in COUNT

3. Given the following data in the old database table products:

id | name    | price
1  | Pen     | 1.20
2  | Notebook| 2.50
3  | Eraser  | 0.80

After migration, the products table in the new database has:

id | name    | price
1  | Pen     | 1.20
2  | Notebook| 2.50

What is the best conclusion?

medium

A. Migration is successful; all data is present

B. Migration failed; table structure is incorrect

C. Migration partially succeeded; price values changed

D. Migration failed; some data is missing

Solution

1. Step 1: Compare row counts and data between old and new tables

   The old table has 3 rows; the new table has only 2 rows.

2. Step 2: Identify missing data

   The row with id 3 (Eraser) is missing in the new table, indicating incomplete migration.

3. Final Answer:

   Migration failed; some data is missing -> Option D

4. Quick Check:

   Missing rows = Migration failure [OK]

Hint: Check row counts and sample data for missing records [OK]

Common Mistakes:

• Ignoring missing rows
• Assuming price changes mean failure
• Confusing structure issues with data issues

4. You wrote a script to compare row counts between old and new databases but it always shows zero for the new database. What is the most likely error?

medium

A. The script is connecting to the wrong new database instance

B. The old database is empty

C. The SQL query syntax is incorrect for the old database

D. The script is not counting rows in the old database

Solution

1. Step 1: Analyze why new database row count is always zero

   If the new database count is always zero, the script might be querying the wrong database or empty table.

2. Step 2: Identify the most common cause

   Connecting to the wrong new database instance is a frequent mistake causing zero counts.

3. Final Answer:

   The script is connecting to the wrong new database instance -> Option A

4. Quick Check:

   Zero count new DB = Wrong connection [OK]

Hint: Verify database connection details carefully [OK]

Common Mistakes:

• Assuming old database is empty without checking
• Blaming SQL syntax for new DB count
• Ignoring connection strings

5. During migration testing, you notice that some records with NULL values in the old database are missing in the new database after migration. What is the best approach to handle this?

hard

A. Ignore NULL records as they are not important

B. Modify the migration script to correctly handle NULL values and rerun migration tests

C. Delete NULL records from the old database before migration

D. Change NULL values to empty strings in the new database manually

Solution

1. Step 1: Identify the issue with NULL values in migration

   Missing records with NULL values indicate the migration script does not handle NULLs properly.

2. Step 2: Choose the best corrective action

   Modifying the migration script to handle NULLs ensures data completeness and correctness.

3. Final Answer:

   Modify the migration script to correctly handle NULL values and rerun migration tests -> Option B

4. Quick Check:

   Handle NULLs in script = Complete migration [OK]

Hint: Always handle NULLs explicitly in migration scripts [OK]

Common Mistakes:

• Ignoring NULL records thinking they are unimportant
• Manually changing data after migration
• Deleting data from source database