I've seen some of the things they are doing in the art project, and I
suspect we can drive down those latencies even more with the "eventually
consistent" flag for batch gets for mass numbers of root entities, given the
rarity of changes in museum collections. Eventually consistent reads are
generally a few hundred ms behind anyway, so for most use cases it works
really well.

The more detailed version of this analysis (I am seeing what I can do to
make most that public) shows that in the 95% percentile, high replication
datastore is generally *faster* for requests, not slow. Why? Because
datastore spikes, are far more infrequent to the point of being almost
non-existent. While we're working on addressing datastore spikes, they are
going to be a fact of life and will never go away. Networks are problematic,
disks slow down, and servers go offline. HR abstracts this nastiness away by
automatically failing over to a separate datastore.

You should almost always pick high replication datastore if possible. There
really aren't any good reasons to pick master/slave over HR.

--
Ikai Lan
Developer Programs Engineer, Google App Engine
Blogger: http://googleappengine.blogspot.com
Reddit: http://www.reddit.com/r/appengine
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On Wed, Feb 2, 2011 at 8:27 AM, Barry Hunter <[email protected]> wrote:

> > It is a good choice to migrate in datastore HR?
>
> Depends on your priorities.
>
> Seems like the biggest reason to switch for the Art project, is there
> should be absolutely no downtime due to scheduled maintainence.
>
>
>
>
> On 2 February 2011 12:20, Brandon Wirtz wrote:
>
> >
> > That said I don’t know how they get a homepage to serve in 250ms
> >
>
> Pretty they just talking about the actual html content, not the whole
> page, static components and all.
>
> takes over 13 seconds in this test:
> http://www.webpagetest.org/result/110202_Z4_2Q8V/1/details/
>
>
> >
> >
> > http://drakaalfirst.appspot.com/blackwater.css
> > is served from static and is 32k in size, it takes 500ms to serve.
> >
>
> Have you enabled billing on your app? So you can take advantage of edge
> caching
>
> but your content doesnt seem much slower...
> http://www.webpagetest.org/result/110202_AM_2Q8K/1/details/
>
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