@CacheEvict for invalidation in Spring Boot - Step-by-Step Execution

Concept Flow - @CacheEvict for invalidation

Method Called

↓

Check @CacheEvict

↓

Evict Cache Entry

↓

Execute Method Body

↓

Return Result

↓

Cache Updated Without Evicted Entry

When a method with @CacheEvict runs, it first removes specified cache entries, then runs the method, ensuring stale data is cleared.

Execution Sample

Spring Boot

@CacheEvict(value = "books", key = "#id", beforeInvocation = true)
public void deleteBook(Long id) {
  bookRepository.deleteById(id);
}

This method deletes a book by id and removes its cache entry from 'books' cache.

Execution Table

Step	Action	Cache State Before	Cache Eviction	Method Execution	Cache State After
1	Method deleteBook(42) called	{"books": {"42": "Book A", "43": "Book B"}}	Evict key 42 from 'books'	Delete book with id 42 from DB	{"books": {"43": "Book B"}}
2	Method returns	{"books": {"43": "Book B"}}	No eviction	No action	{"books": {"43": "Book B"}}

💡 Method completes after evicting cache key 42 and deleting book 42 from database

Variable Tracker

Variable	Start	After Step 1	After Step 2
cache.books	{"42": "Book A", "43": "Book B"}	{"43": "Book B"}	{"43": "Book B"}
method.id	N/A	42	42

Key Moments - 2 Insights

Why does the cache entry get removed before the method runs?

Because @CacheEvict removes the cache entry first to avoid stale data if the method changes data, as shown in execution_table step 1.

What happens if the cache key does not exist when @CacheEvict runs?

No error occurs; eviction silently skips missing keys, so cache state remains unchanged except for confirmed evictions (see execution_table).

Visual Quiz - 3 Questions

Look at the execution_table, what is the cache state after step 1?

A {}

B {"books": {"43": "Book B"}}

C {"books": {"42": "Book A", "43": "Book B"}}

D {"books": {"42": "Book A"}}

💡 Hint

Check the 'Cache State After' column in row for step 1.

At which step does the method delete the book from the database?

A Step 1

B Step 2

C Before Step 1

D After Step 2

💡 Hint

Look at the 'Method Execution' column in execution_table.

If the @CacheEvict annotation was removed, what would happen to the cache after method execution?

A Cache would be empty

B Cache would remove all entries

C Cache would still contain the old entry for key 42

D Cache would add a new entry for key 42

💡 Hint

Refer to the cache eviction step in execution_table step 1.

Concept Snapshot

@CacheEvict removes cache entries before method runs.
Use value to specify cache name.
Use key to specify which entry to evict.
Prevents stale data after data changes.
Eviction happens even if method fails.

Full Transcript

When a method annotated with @CacheEvict is called, Spring first removes the specified cache entry. This prevents stale data from remaining if the method changes data. After eviction, the method body executes, such as deleting a record from the database. Finally, the method returns, and the cache no longer contains the evicted entry. If the cache key does not exist, eviction silently skips it without error. This ensures cache consistency with the data source.