Custom query methods by naming convention in Spring Boot - Performance & Optimization

Performance: Custom query methods by naming convention

MEDIUM IMPACT

This affects how quickly the database queries are generated and executed, impacting page load and response times.

Defining database queries in Spring Data repositories

Spring Boot

List<User> findByNameContaining(String name);

Simpler method names reduce parsing complexity and generate straightforward queries, improving startup and query execution speed.

📈 Performance GainReduces query parsing time and risk of inefficient queries; faster startup and query execution.

Defining database queries in Spring Data repositories

Spring Boot

List<User> findByNameContainingIgnoreCaseOrderByAgeDesc(String name);

Complex method names can lead to slower query parsing and harder-to-maintain code if overused.

📉 Performance CostAdds slight overhead during startup for parsing complex method names; can cause inefficient queries if naming is ambiguous.

Performance Comparison

Pattern	Query Parsing Cost	Query Execution Cost	Startup Impact	Verdict
Complex method names with many keywords	High	Variable (depends on query)	Medium	[!] OK
Simple, clear method names	Low	Low	Low	[OK] Good

Rendering Pipeline

Spring Data parses method names at application startup to generate SQL queries, which are then executed during request handling.

→Query Parsing

→Query Execution

⚠️ BottleneckQuery Parsing at startup if method names are overly complex

Core Web Vital Affected

LCP

This affects how quickly the database queries are generated and executed, impacting page load and response times.

Optimization Tips

1Keep custom query method names simple and clear.

2Avoid chaining too many keywords in method names.

3Test generated queries to ensure efficiency.

Performance Quiz - 3 Questions

What is a performance benefit of using simple custom query method names in Spring Data?

A Increased bundle size

B More complex SQL queries generated

C Faster query parsing at application startup

D Slower database connection

DevTools: Spring Boot Actuator / Logs

How to check: Enable debug logging for Spring Data repositories and observe query parsing messages during startup.

What to look for: Look for long parsing times or warnings about ambiguous method names indicating performance issues.

Practice

1. What does a Spring Data JPA method named findByLastName do?

easy

A. Counts records where the lastName matches the given value

B. Deletes records where the lastName matches the given value

C. Checks if any record exists with the given lastName

D. Finds all records where the lastName matches the given value

Solution

1. Step 1: Understand the method prefix

   The prefix findBy in Spring Data JPA means it will search and return matching records.

2. Step 2: Analyze the property name

   The method uses LastName as the property to filter by, so it finds records with that lastName.

3. Final Answer:

   Finds all records where the lastName matches the given value -> Option D

4. Quick Check:

   findBy + property = find matching records [OK]

Hint: findBy means search and return matching records [OK]

Common Mistakes:

• Confusing findBy with deleteBy or countBy
• Thinking it returns a boolean instead of records
• Ignoring the property name after findBy

2. Which of the following is the correct syntax for a method that counts users by their age in Spring Data JPA?

easy

A. findCountByAge(int age);

B. countUsersByAge(int age);

C. countByAge(int age);

D. countAgeBy(int age);

Solution

1. Step 1: Identify the correct prefix for counting

   The correct prefix to count records is countBy.

2. Step 2: Check method naming pattern

   The method should be countByAge to count users filtered by age.

3. Final Answer:

   countByAge(int age); -> Option C

4. Quick Check:

   countBy + property = count matching records [OK]

Hint: Use countBy + property to count records [OK]

Common Mistakes:

• Adding extra words like Users in method name
• Using findCountBy which is invalid
• Placing property name after count instead of after By

3. Given the method existsByEmailAndStatus(String email, String status), what will it return if a user with email "[e-mail]" and status "active" exists?

medium

A. A list of users matching the email and status

B. true

C. false

D. The count of users matching the email and status

Solution

1. Step 1: Understand the method prefix

   The prefix existsBy returns a boolean indicating if any record matches the criteria.

2. Step 2: Analyze the condition

   The method checks if a user exists with the given email and status combined with And.

3. Final Answer:

   true -> Option B

4. Quick Check:

   existsBy + conditions returns boolean [OK]

Hint: existsBy returns true if matching record exists [OK]

Common Mistakes:

• Expecting a list instead of boolean
• Confusing existsBy with findBy
• Ignoring the combined conditions with And

4. Identify the error in this Spring Data JPA method declaration: List<User> findByNameOr(int age, String name);

medium

A. The method name is missing the property after 'Or'

B. The method should use 'And' instead of 'Or' for combining conditions

C. The order of parameters does not match the method name conditions

D. The return type should be boolean for 'findBy' methods

Solution

1. Step 1: Analyze the method name structure

   The method name uses 'Or' but does not specify the property after 'Or'. It should be like 'findByNameOrAge'.

2. Step 2: Check parameter order and names

   Parameters should match the properties in the method name order, but the main error is missing property after 'Or'.

3. Final Answer:

   The method name is missing the property after 'Or' -> Option A

4. Quick Check:

   Method names must specify property after 'Or' [OK]

Hint: After 'Or' or 'And', always specify property name [OK]

Common Mistakes:

• Leaving out property name after 'Or' or 'And'
• Mixing parameter order with method name order
• Using wrong return type for findBy methods

5. You want to create a method that finds all orders where the customer's city is "New York" and the order total is greater than 100. Which method name correctly follows Spring Data JPA naming conventions?

hard

A. findByCustomerCityAndOrderTotalGreaterThan(String city, double total);

B. findOrdersByCityAndTotalGreater(String city, double total);

C. findByCityAndOrderTotalGreaterThan(String city, double total);

D. findByCustomerCityAndOrderTotalGreater(String city, double total);

Solution

1. Step 1: Identify the correct property names

   The properties are nested: customer.city and orderTotal. The method name must reflect this exactly.

2. Step 2: Use correct keywords for comparison

   For 'greater than', the keyword is 'GreaterThan' in Spring Data JPA method names.

3. Step 3: Combine conditions with 'And'

   The method name should combine both conditions with 'And' and use full property paths.

4. Final Answer:

   findByCustomerCityAndOrderTotalGreaterThan(String city, double total); -> Option A

5. Quick Check:

   Use full property names + GreaterThan + And [OK]

Hint: Use full property names and 'GreaterThan' for > comparisons [OK]

Common Mistakes:

• Using incomplete property names
• Using 'Greater' instead of 'GreaterThan'
• Omitting 'By' after 'find'