In a system using WAL, all modifications are written to a log before they are applied. Usually both redo and undo information is stored in the log.
WAL allows updates of a database to be done in-place. Another way to implement atomic updates is with shadow paging, which is not in-place. The main advantage of doing updates in-place is that it reduces the need to modify indexes and block lists.
Big History is a way to examine history from the Big Bang to the present. It examines long time frames using a multidisciplinary approach based on combining numerous disciplines from science and the humanities.
There are different systems for organizing knowledge about all things known to humankind. One way is the Dewey System, where decimals indicate subject. 600 is technology and medicine, 620 is engineering of railroads and roads, etc. I was thinking something different: a big history way of organizing what is known. Start with the Big Bang, continue with the sciences that spring up from there (Physics, Chemistry) later when life starts on Earth add biology, writing, languages, architecture, and then get to railroads and roads. So it’s a chronological way of organizing the tree of knowledge.
After building this chronological tree (small task!) we need a way to “sample” it. A way to say “this is a slice of all history and pre-history known today, with your background from Country/Region X with languages Y and Z, these topics can be relevant”. Or the “Amazon” way of suggesting: “You might also be interested in ‘Quasi Stationary Simulation of Railway Engines’.”