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From Jason Smith <...@iriscouch.com>
Subject Re: Frugal Erlang vs Resources Hungry CouchDB
Date Sat, 02 Jul 2011 06:50:33 GMT
On Fri, Jul 1, 2011 at 10:23 PM, Jens Alfke <jens@mooseyard.com> wrote:
>
> On Jun 30, 2011, at 11:37 PM, Zdravko Gligic wrote:
>
>> But neither one even bothered trying to answer my question of whether
>> just the last updated header or perhaps the last few are ever used.
>
> Just the last one. But at any point in time, the last one is vital for recovery. It just
becomes useless after another one is successfully appended.

Isn't that what I said? :)

The evidence indicates "no." That's a shame. In my daily life I always
worry about starting from an accidental advantage (speaking English),
and assuming everybody else is advantaged, ultimately only causing
confusion. In other words: Most Americans talk too fast, with too much
slang.

Anyway, to right my wrong and make it clear:

The bottom rung of a ladder *was* important, when you stepped on it.
Once at the top, we do not care about the bottom rungs.

Similarly, the food you ate last year kept you alive, so it *was* very
important. But today, last year's food is not relevant.

With CouchDB (as others said), the last header is the important one;
but once a new one is written, the old header is not relevant.

(They might be *slightly* relevant in rare cases. For example, if your
tape media was damaged and you have a partial backup; the old headers,
now at the "end" of the truncated .couch file, are once again useful
to access the older data. That situation however is very unlikely
and/or completely contrived.)

-- 
Iris Couch

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