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From Mark Hahn <m...@hahnca.com>
Subject Re: following fast doc updates
Date Tue, 25 Sep 2012 21:41:12 GMT
> Alternatively, you could use two dbs.

I came up with two are three schemes that require twice the number of
writes.  It bothers me to double the number of writes, although maybe it
shouldn't.

Right now I'm implementing a scheme where a hash is saved in ram for every
doc id and "change type" with the version number of that change.  A "change
type" table is also kept in the doc with the version number that the
changed happened in.  By comparing the two version numbers I can detect
each unique change, even when multiple have occured.

Boy this is a pain.  If somone can come up with a simpler scheme to catch
each unique change it would be appeciated.

On Tue, Sep 25, 2012 at 12:02 PM, Paul Davis <paul.joseph.davis@gmail.com>wrote:

> Alternatively, you could use two dbs. One db you could write "change
> requests" to (each request as a new doc) and then listen for changes
> on that and apply them in that logic. This also has that added benefit
> that you could do the timestamped dbname pattern for your changes feed
> dbs to (possibly depending on use case) remove some of the cruft
> buildup.
>
> On Tue, Sep 25, 2012 at 1:31 PM, Mark Hahn <mark@hahnca.com> wrote:
> >> The _changes feed only ever shows leaf revisions
> >
> > AARRGGHH.  I am so screwed.  I have been working on a scheme that relies
> on
> > tracking every change.  And as everyone knows there is normally no way to
> > find out what changed in a doc.  I am going to have to add a history of
> > changes to each doc which it not only wasteful, but a pain to implement.
> >
> > Thanks for taking the trouble to give me bad news.
> >
> >
> > On Tue, Sep 25, 2012 at 10:19 AM, Adam Kocoloski <kocolosk@apache.org
> >wrote:
> >
> >> On Sep 24, 2012, at 5:16 PM, Mark Hahn <mark@hahnca.com> wrote:
> >>
> >> > If I update a particular doc multiple times rapidly, is each update
> >> > guaranteed to show up in a continuous changes feed?  I am worried that
> >> the
> >> > change feed will be optimized to just show the latest value of a doc
> with
> >> > multiple updates.  This would break my logic.
> >>
> >> Your worries are justified.  The _changes feed only ever shows leaf
> >> revisions (i.e., latest updates to branches of the edit tree).  Regards,
> >>
> >> Adam
>

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