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A comment on Datomic: Can Simple be also Fast?. Parent comment

Re:Datomic: Can Simple be also Fast? by jimbokun on Sunday September 22, 2013 @09:17PM (#6428764)
Given the underlying architecture of most relational databases, is it realistically possible to do "point in time queries", without requiring playing back the entire log history into a clean database up to the point in time you want? That's not going to be very efficient.

I've only seen SQL logs presented as solutions to replication and disaster recovery, not point in time functionality.

What I'm getting at, is it even possible in principle to expose part of the inner workings of some relational database systems to get this kind of capability?

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Re:Datomic: Can Simple be also Fast? by strictfp on Monday September 23, 2013 @02:05AM (#6429363)
Snapshotting and log replay should be fairly straightforward, if you save all sql statements in their entirety. Snapshots would stop the world, which might pose a problem, but I presume this is no different to other event sourcing solutions. Given the concurrency of a db, I'm also not sure that there's a strict ordering of all incoming statements.

Edit: Seems like at least Oracle is already doing this: http://en.wikipedia.org/wiki/Redo_log

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Re:Datomic: Can Simple be also Fast? by twic on Monday September 23, 2013 @02:04PM (#6432908)
Not only is this possible, Oracle has had exactly that feature since 2002:

http://docs.oracle.com/cd/E11882_01/appdev.112/e17125/adfns_...

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