Problem Statement: Problem Statement

Detection

• Detection

• We want to add more memory/buffers to a buffer pool only when the working set doesn’t fit.
• To determine when to extend the buffer pool, we keep track of the cache hit ratio of each buffer pool by sampling the cache hit ratio once a minute for 5 minutes.
• If the average cache hit ratio is less than a configured threshold, we extend the buffer pool.

• Extension

• In order to support buffer pool extension, we need to move buffer pools into their own shared memory segments.

• Shared Memory in Informix can now have 5 possible segments

• Resident
• Virtual
• Message
• Bufferpool *** NEW ****
• Extended

Bufferpool Segments

• Bufferpool Segments

• Buffer pools will no longer be allocated within the resident segment.
• We will add a new IDS memory segment class that will contain only buffer pool memory structures and adhere to the RESIDENT flag.
• The buffer pool class segment will have virtually no overhead (bitmap or TTree) for maintaining the segment. This will allow for maximum memory usage.
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