When a server receives data it stores this in a buffer. The buffer is immediately saved on disk and is also kept in memory. The buffer can store a fixed number of points for each time series. This number depends on the buffer size which can be configured when creating a database. Since SiriDB does not read from the buffer-file, it does not matter in which order the points are saved. In memory the points are saved in order so queries can return the points from the buffer very fast.
When the buffer for a time series is “full” and new points can’t be saved, then both the new, and the buffer data will be sent to shards.