Hi Jan Thanks for your detailed explaination. Based on what you said, arangodb (mmap engine) is similar with mongodb (mmapv1).
Well I can wait for 3.2 anyway. Regards gelin yan 在 2017年6月12日星期一 UTC+8下午3:28:15，Jan写道： > > Hi, > > when index size gets bigger than the available RAM, then it depends on the > configuration of your operating system what will happen exactly: > - when there is swap space configured and swap space is available, the OS > will assign disk-based memory for the index data, which will slow down > index operations from in-memory speed to on-disk speed > - if there is no swap space available, then either operations in ArangoDB > will fail with an out-of-memory error, or worse, the operating system may > trigger its OOM killer to terminate the process with the highest RAM usage, > which will likely be arangod. > > Note that all of the above applies for ArangoDB 3.1 and earlier. From > ArangoDB version 3.2 on, we do offer an alternative storage engine based on > RocksDB. This storage engine is designed to handle data bigger than the > available RAM. With the RocksDB-based storage engine, index data that is > not in RAM will be loaded from disk when it is not in the in-memory hot > set. So operations that need to load data from disk will be slower than > operations that can access data already in RAM. The engine will > automatically keep the hot set in memory, so if you're only accessing a hot > set of data that fits into the available RAM, it should be fine. If you > will be accessing your entire data set and it is much bigger than RAM, then > all operations will slow down. But there is no way to avoid this, even with > other databases, which will behave similarly. > ArangoDB 3.2 is currently in the end of its alpha stage, and will very > soon go into beta stage. I recommend to give it a test drive and try the > new storage engine that is shipped with it. > > Best regards > Jan > > -- You received this message because you are subscribed to the Google Groups "ArangoDB" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
