When Neptune perform a query, I expected Neptune pull the vertex and edge data out from volume storage, and then put these data into memory. How long does Neptune keep these data in memory?

CodePudding user response：

It's hard to give an exact answer to that due to the way the buffer cache in Amazon Neptune works. Amazon Neptune uses ~2/3 of the memory of any specific instance for buffer cache. When a value is needed, Neptune first checks the buffer cache and if it is not there, then it loads the page into memory (each page is 16kB). Once the buffer cache fills up Neptune will evict the least recently used page from the cache.