What are the memory elimination strategies for redis?

Redis provides multiple memory elimination strategies to control how data is processed when there is insufficient memory. These strategies include: noeviction: disables memory eviction to ensure data is not lost. volatile-lru: Eliminate the key that has not been used for the longest time and has an expiration time set. volatile-ttl: Eliminate the key with the shortest expiration time that has set expiration time. volatile-random: Randomly eliminate keys with expiration time set. allkeys-lru: Eliminate all keys that have not been used for the longest time, including keys with no expiration time set. allkeys-random: Randomly eliminate all keys, including keys with no expiration time set. eviction-algo: Since

Redis’s memory eviction strategy

#Redis provides a variety of memory eviction strategies to Controls how data is processed and removed when the Redis instance runs out of memory. The following are the memory elimination strategies available in Redis:

1. noeviction (default)

• Description: Disable memory elimination, Redis Data is never actively cleared.
• Advantages: Ensures that data will not be lost, suitable for scenarios that require high data durability.
• Disadvantages: If memory is exhausted, Redis will stop accepting new writes, potentially causing performance issues.

2. volatile-lru

• Description: Eliminate the key that has not been used for the longest time and has an expiration time set.
• Advantages: Release expired keys and free up memory space when memory is limited.
• Disadvantages: Expired keys may still be used, resulting in data loss.

3. volatile-ttl

• #Description: Eliminate the key with the shortest expiration time that has set expiration time.
• Advantages: Free up memory space while retaining expiring keys that may still be needed.
• Disadvantages: Keys that are still valuable may be retired early.

4. volatile-random

• Description: Randomly eliminate keys with expiration time set.
• Advantages: Simple and fair, avoiding accumulation of expired keys.
• Disadvantages: Keys that are still valuable may be eliminated.

5. allkeys-lru

• Description: Eliminate all keys that have not been used for the longest time, regardless of whether the expiration time is set or not .
• Advantages: Releases memory space, suitable for scenarios where there are many keys with no expiration time set.
• Disadvantages: Keys that are still valuable may be eliminated.

6. allkeys-random

• Description: Randomly eliminate all keys, regardless of whether the expiration time is set.
• Advantages: Simple and fair, avoids key stacking.
• Disadvantages: Keys that are still valuable may be eliminated.

7. eviction-algo (new in Redis 4.0)

• Description: Customize eviction strategy, use Lua The script specifies elimination rules.
• Advantages: Provides a high degree of customizability, allowing users to create complex elimination rules based on specific needs.
• Disadvantages: Requires writing additional Lua scripts, which may involve higher development costs.

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