Re: Using null date fields to indicate active/expired records

On Fri, Aug 06, 2004 at 10:27:17AM -0700, Josh Berkus wrote:
> Brian,
>
> > Approximately 14 billion. Ok, I'm kidding, but can anyone answer
> > my question? Although this might be micro-optimization, does it
> > hurt to know more about date performance?
>
> No, there's nothing wrong with knowing. What David and I are
> asserting is that your decision should be determined by having a
> correct data model, and not by counting bits, unless you're in a
> really extreme situation where you have already tested and know you
> have a problem.
>
> Josh's Database Rules #3: the performance loss for slow queries is
> generally exceeded by the downtime caused by a bad data model by a
> factor of 100 or more.

A corollary, Dave's Database Rule #187, is that Josh's Database Rule
#3 wildly underestimates this factor.

> > There are two parts to my question; one, which is faster, and two,
> > does anyone have any advice about using either a single boolean
> > flag or using a 1-n type date?
>
> Which is faster depends on your query structure and the distribution
> of your data; that's the other reason not to make decisions on this
> basis now. If you want a serious answer on this, please post your
> current table structure and an explanation of what kind of data is
> kept in the various fields and how you query it.

Yep.

Cheers,
D
--
David Fetter david(at)fetter(dot)org http://fetter.org/
phone: +1 510 893 6100 mobile: +1 415 235 3778

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