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Date: Wed, 4 Aug 2010 12:45:14 +1000
Message-ID: <AANLkTikY4AZ+HQ0vunGw9USsqp7d85Nu+UEzWOZ2aak-@mail.gmail.com>
Subject: Re: VIEW Performance Testing Help
From: Steven Prentice <steven.prentice.87@gmail.com>
To: user@couchdb.apache.org
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On Wed, Aug 4, 2010 at 12:07 PM, Steven Prentice <
steven.prentice.87@gmail.com> wrote:

>
>
> ---------- Forwarded message ----------
> From: Paul Joseph Davis <paul.joseph.davis@gmail.com>
> Date: Wed, Aug 4, 2010 at 11:58 AM
> Subject: Re: VIEW Performance Testing Help
> To: "user@couchdb.apache.org" <user@couchdb.apache.org>
>
>
>
>
>
>
> On Aug 3, 2010, at 7:31 PM, Steven Prentice <steven.prentice.87@gmail.com>
> wrote:
>
> > Hey Couchinators!
> >
> > My friend and I are trying to test the impact that views have on the size
> of
> > the database and have a few questions...
> >
> > 1. if the value of a view is set to 'doc' does that mean that the leaves
> of
> > the view B-Tree are now documents or are they simply pointers to the
> > document leaves in the database B-Tree?
> > i.e would the summed memory of all of the values in the view be equal to
> the
> > size of the database (ignoreing revisions)?
>
> Whatever you emit as a value is stored  in the btree. So if you emit an
> entire document it is stored completely in that view. A way to avoid this is
> to use the include_docs=true parameter but it has some read performance
> trade offs because it's a lookup per view row. The best idea is to only emit
> what's actually needed.
>
>
> > 2. also we would like to know if the database size that is displayed in
> > futon includes the size of the views?
>
> Unless I missed that commit, no, db size is the size of just the .couch
> file.
>
> > 3. Oh also, Revisions...is a revision an entire document or does a
> revision
> > only track changes in a document?
>
> Neither. A revision is just the string-id pair (More precisely it's a node
> in the revision tree, but it still has zero info on actual document
> content). That's all that will remain on disk after a compaction. Because
> we're tail append the previous entire documents remain on disk until
> compaction. To illustrate, we've had discussions on removing access to old
> revisions and renaming revision to something else that doesn't make people
> think they'll always have access to old versions of a document.
>
> > Cheers
> > Steve + Adam
>
> HTH,
> Paul Davis
>
> How would we check how much space that just the views are taking up?
cheers!

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