HN always seems pretty fast and is probably well designed from a data structure standpoint.It seems that each comment and submissions are assigned a monotonically increasing number; do both submissions and comments share the same numeric space?How is the content hierarchy stored? Is it a single large table with (for example) a structure that looks like id, parentID, contenttype, content?Is data stored in an OLAP SQL database, on disk as flat files, in DBM files, etc?What kind of performance is required? Is the database distributed across more than one machine?