The in-memory feature enables fast aggregation using Vertical Clustered Index (VCI) and memory-resident feature.
VCI has a data structure suitable for aggregation, and features parallel scan and disk compression, which enable faster aggregation through reduced disk I/O.
The memory-resident feature reduces disk I/O that occurs during aggregation. It consists of the preload feature that reads VCI data to memory in advance, and the stable buffer feature that suppresses VCI data eviction from memory. The stable buffer feature secures the proportion specified by parameter in the shared memory for VCI.
This chapter describes how to install and operate the in-memory feature.
This feature can only be used in Advanced Edition.
