Get Memory Fragmentation Ratio in PHP Redis (Detailed Guide w/ Code Examples)

Use Case(s)

The memory fragmentation ratio in Redis can be used for monitoring and managing server performance. It helps in determining how efficiently Redis is using memory and if there might be issues regarding memory allocation.

Code Examples

To get the memory fragmentation ratio, you can use the info command which provides a lot of information about the current state of the Redis server, including the memory fragmentation ratio.

<?php $redis = new Redis(); $redis->connect('', 6379); $info = $redis->info(); echo 'Memory Fragmentation Ratio: '. $info['mem_fragmentation_ratio']; ?>

In this example, we first connect to the Redis server running on localhost. Then we use the info method of the Redis class to fetch server stats. We echo out the memory fragmentation ratio from these stats.

Best Practices

  1. Regularly monitor your Redis instance's memory fragmentation ratio. It can help identify memory management issues early.

  2. Remember that a high fragmentation ratio (much greater than 1.5) usually indicates that Redis is holding onto more memory than it actually needs, whereas a low ratio (close to 1.0) means Redis is efficiently utilizing memory.

Common Mistakes

  1. Not keeping an eye on the memory fragmentation ratio can lead to inefficient memory usage by Redis, which could eventually impact application performance.

  2. Misinterpreting the value of memory fragmentation ratio can lead to unnecessary troubleshooting or missing actual problems.


  1. Q: What is a good memory fragmentation ratio in Redis? A: A good fragmentation ratio is typically around 1. It means that Redis is efficiently using its allocated memory. However, the acceptable range can depend on specific system and application characteristics.

  2. Q: How can I reduce memory fragmentation in Redis? A: Memory defragmentation in Redis is mostly handled by the Redis server itself. If you are noticing high fragmentation ratios consistently, it could be due to how your data is structured or the types of operations you are performing. You might need to adjust these factors or consider using a different data store strategy.

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