XTDB is a general-purpose bitemporal database with graph query capabilities:  https://xtdb.com/
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The talk expands on what "bitemporal" means in this context, namely, separate "valid" and "audit" time dimensions. The discussion upthread is a good example: if you accidentally mark down inventory in the wrong location and you find out later, you should backdate the fix to when you did the count -- this is the 'valid' dimension, but the fact that you changed it today should also be recorded so it can be reviewed later -- this is the 'audit' dimension.