# Prepared Plan Cache
+ `enabled`: Reduce the computational overhead caused by execution plans, so that statement of the same type use the same execution plan, and improve performance, at the cost of which execution plans may not be optimal when data or query conditions change.
+ `capacity`: Used to limit cache size(number of cache entries) to avoid excessive use of memory. If the application uses lots of different types of requests, which exceeds the capacity up-limit, then plan cache effect will be discounted.
![center](./student-guide/diagram/06-prepared-plan-cache-01-01.png)
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Prepared Plan Cache
- enabled/capacity
  - Reduce computational overhead caused by execution plans after enabling statement of the same type to use the same execution plan, improving performance at the cost that execution plans may not be the best when data or query conditions change
  - Capacity is used to limitation the size of the cache to avoid using too much memory. If the application uses a large number of different types of request and exceeds the capacity limit, the effect of plan cache will be compromised