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InfoQ Homepage Presentations The Impedance Mismatch is Our Fault

The Impedance Mismatch is Our Fault

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Bio

Stuart Dabbs Halloway is a co-founder of Relevance, Inc. Stuart is the author of Programming Clojure, Component Development for the Java Platform, and Rails for Java Developers. He regularly speaks at industry events including the No Fluff, Just Stuff Java Symposiums, the Pragmatic Studio, RubyConf, and RailsConf.

About the conference

For the second time we are launching the GOTO Copenhagen conference in May 2012 after a successful execution in 2011. GOTO Aarhus has been an annual event in Denmark since 1996 and attracts more than 1200 participants (formerly known as JAOO). The target audience for GOTO conferences are software developers, IT architects and project managers.http://gotocon.com/

Recorded at:

Oct 02, 2012

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Community comments

  • Interesting discussion about temporal database

    by peter lin /

    Your message is awaiting moderation. Thank you for participating in the discussion.

    Just as a suggestion for the next talk by Datomic developers. How does Datomic differ from temporal databases? Over 2 decades of research on active/temporal databases exposed a lot of issues related to storage and query of temporal data.

    Even with Datomic's approach, it doesn't seem to provide a full solution for bi-temporal problems. Though it would make it easier to build a bi-temporal database on top of datomic. Once you go three dimensions or more, the tree analogy doesn't fit so neatly. One example of this is back dated changes. Visualizing back dated changes as a tree doesn't fully express what happened, but that's a very difficult problem that no one has solved.

  • Re: Interesting discussion about temporal database

    by Rafal Babinicz /

    Your message is awaiting moderation. Thank you for participating in the discussion.

    How does Datomic differ from temporal databases? - Goals and principles are different:
    www.datomic.com/rationale.html
    www.infoq.com/presentations/Datomic-Database-Value
    www.infoq.com/presentations/The-Design-of-Datomic

  • Re: Interesting discussion about temporal database

    by peter lin /

    Your message is awaiting moderation. Thank you for participating in the discussion.

    I don't really care about the goals and principles to be honest. I've already watched all the talks by Rich about datomic on InfoQ. From a "rubber meets the road" perspective, how does Datomic make it easier to query for bi-temporal data? Is there a query language and how does it make it easier to query for data with transaction and valid time?

    I understand that Datomic is "value oriented" and transactions are timestamped with a user visible timestamp. So that seems to address the issue of saving data, in that all saves are really inserts or what stuart calls "add operations".

    Having built bi-temporal databases on top of sql and nosql databases numerous times over the years, the challenge is much greater than just saving data. I would argue one could have different goals and principles and still arrive at a "value oriented" database. There's dozens of papers and several books that cover the topic of active/temporal databases. Many of them share similar philosophy of value orientation. At the end of the day though, if a developer needs to be able to query data by transaction time and valid time, how does Datomic make life easier? In the insurance industry, it's common to query for the history of a record for auditing purposes and many other things. These temporal issues have been around for decades now.

  • Datalog expressiveness

    by Harald Beck /

    Your message is awaiting moderation. Thank you for participating in the discussion.

    Ad slide 34: In Datalog you can express transitive closures, in relational algebra you cannot. (Therefore they are not equivalent.)

  • Re: Datalog expressiveness

    by Stuart Halloway /

    Your message is awaiting moderation. Thank you for participating in the discussion.

    Correct. I typically say "relational algebra plus recursive query" -- apologies if I left that out of the slide.

  • Can you please make me understand time in the Datom a bit more?

    by abhishek manocha /

    Your message is awaiting moderation. Thank you for participating in the discussion.

    Like, whats the memory implications of these? Isnt it our storage going to blow up? What about redundant data (in the past like you said) What of that is no use to me? Shouldnt this go in our programming, why it should be part of data at all?

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