Database Buffer Cache: It can be divided into approximately three memory segments, and any segment should be placed in one part of the memory. All these parts of memory, which belong to the Database Buffer Cache, have an LRU list and a Checkpoint Queue.

The Database Buffer Cache can be divided as follows:

• Default Pool: The size of this part is controlled via the variable DB_CACHE_SIZE, and this part of memory is the only required one in the Database Buffer Cache. All segments that require caching are handled in the Default Pool.
• Keep Pool: This part is created by configuring the variable DB_KEEP_CACHE_SIZE. It ensures that some blocks within the segments remain in memory. The space for this memory part should be sufficient to store the entities that you want to retain in it.
• Recycle Pool: This part of memory ensures that blocks that are unlikely to be reused are quickly removed from memory. It is created by configuring the variable DB_RECYCLE_CACHE_SIZE. This pool should generally be small.