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#6638 open
Martin Tepper

Autogenerated fixture ids too long for some MySQL integer types

Reported by Martin Tepper | March 28th, 2011 @ 01:59 PM | in 3.1

We've came across this by accident. Some of our tables had the primary key column "id" set to SMALLINT ( to save a little disk space. The problem is that the ids generated by Fixtures::identify are too long - they don't take the length of the target column into account, being just a modulo'd hash of the name.

This is on Rails 2.3.11.

The question is, is this something warranting attention ?
I'd like to go and try to make a test and a fix for this, as I consider this a bug - the magic fixtures should be magic enough to work on smaller columns.

But will a solution, which might make the Fixture system more complicated, be accepted ? Or is this too much of an edge case ?

Comments and changes to this ticket

  • Andrew White

    Andrew White March 28th, 2011 @ 09:33 PM

    • Importance changed from “” to “Low”

    Wouldn't it be easier just to convert the columns to INT? What's the justification for keeping them as SMALLINT - performance difference would be next to nothing and at most you'd save 130KB before you overflowed the id column. I can see the logic of keeping other columns as small as possible if you're dealing with millions of rows but not for the primary key column.

  • Martin Tepper

    Martin Tepper March 29th, 2011 @ 04:21 PM

    Well, the justification is that if you reference the primary id from other tables, and if those have a large number of rows, the few bytes per foreign key entry can add up. Especially if you have (multiple) indices on the foreign keys.
    This will probably not be a game-changer for one table, but when you are in a tight spot memory-wise on your DB server, you're trying to optimize where you can.

  • Andrew White

    Andrew White March 29th, 2011 @ 04:27 PM

    • State changed from “new” to “open”
    • Milestone set to 3.1
    • Assigned user set to “Andrew White”

    Yep, I can see that would make a difference - go ahead and see if you can fix it.

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