← Back to context

Comment by abstractbill

13 years ago

Why should it be? You can get a long long way by treating the filesystem as a database. The first engineers at Amazon used the same technique a lot, as do I.

Because you always end up building your own database out of flat files and that is always worse than using an existing one.

  • If it was always worse then every developer doing this must be stupid. Here are some ways in which a filesystem is "better":

    - Zero administration

    - Only configuration setting is the directory

    - Trivial to test

    - Trivial to examine with existing tools, backup, modify etc

    - Works with any operating system, language, platform, libraries etc

    - Good performance characteristics and well tuned by the operating system

    - Easy for any developer to understand

    - No dependencies

    - Security model is trivial to understand and is a base part of operating system

    - Data is not externally accessible

    Many existing databases have attributes that aren't desirable. For example they tend to care about data integrity and durability, at the expense of other things (eg increased administration, performance). For a use case like HN, losing 1 out of every 1,000 comments wouldn't be that big a deal - it isn't a bank.

    Consider the development, deployment and administrative differences between doing "hello world" with a filesystem versus an existing database. Of course this doesn't always mean filesystems should be used. Developers should be practical and prudent.

    TLDR: YAGNI, KISS, DTSTTCPW

  • And yet, here you are, on a site run off a flat file database.

    • Just a nitpick. A "flat file" database suggests encoding all the data to a single file.

      Using a files system as a database is a little different as file systems are databases in their own right.

      The question to ask is "is the data I want to store in my 'database' enough like the data stored in a filesystem that I can just use the filesystem as my database?"

    • A commenting site that:

      - Has average latency over 500ms when not under load - Performs quite poorly under load (I hate to bring it up, but the most recent example was Aaron Swartz's passing. Anyone who used HN then to get news knows how poorly HN performs under load) - Is restarted every week or two because it leaks memory - Keeps XSRF tokens in memory and loses them across restarts - Doesn't have a full markup language

      HN is quite poorly-featured compared to typical commenting sites. People use HN because pg is here. He could remove half the features on the site (bold & italics... what features are there even to remove beside nested commenting?) and retain 90% of the audience.

      12 replies →

  • Just as one example, I think you could make a fairly convincing case that the official version of git uses a "filesystem as a database" system with great success.

    I doubt it would be improved by using something more "proper".

  • Well, no. There are some exceptions, but most databases add a whole lot of bloat you don't necessarily need. Simple files can be just as fast or even faster than using a big database - which is the most important metric to me.

  • Even if that was true, I'd still tell people to start with flat files for a new project. It's like the advice to do a job yourself before hiring for it: You'll be better equipped to judge how well a database is managing your data if you've already done it yourself.