On Dec 15, 2009, at 3:40 PM, Jeff Davis wrote:

Based on the premise that timestamps are a continuous value and the
granularity/precision is entirely an implementation detail, you're
right. But I disagree with the premise, at least in some cases that I
think are worthwhile.

The argument is, in essence:

        DECIMAL is continuous.
        DECIMAL(10,3) is discrete.

timestamptz in general is a continuous value (unless we're talking Planck times :) ). There is no way for us to guarantee that next(timestamptz) will have the same value across all platforms; its epsilon is platform dependent.

However, if we specify a scale on timestamptz, it becomes much more useful. Just making up a syntax, if we had timestamptz(milliseconds), then it's discrete and we know what next(timestamptz(milliseconds)) is.

But in the current implementation, the only way I can see making that work is if we specify a scale for timestamptz, and that strikes me as a big change to its semantics.

--
-- Christophe Pettus
   x...@thebuild.com


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