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From Vladimir Ozerov <voze...@gridgain.com>
Subject Re: affinity key syntax
Date Wed, 25 Oct 2017 10:39:21 GMT
In Spanner once parent key is found you don't need to search for child keys
from scratch - they are located just after the parent key in the tree. In
Ignite child and parent keys are located in different trees, hence more
lookups are needed.

On Wed, Oct 25, 2017 at 1:36 PM, Dmitriy Setrakyan <dsetrakyan@apache.org>
wrote:

> On Wed, Oct 25, 2017 at 3:32 AM, Vladimir Ozerov <vozerov@gridgain.com>
> wrote:
>
> > Dima,
> >
> > Yes, I saw it also. But this is not about syntax only. Spanner use this
> > information to store data efficiently - child entries a located near to
> > their parents. We can think of it as if all related tables were logical
> > caches inside one physical cache, sorted by the key. With this storage
> > format it will be possible to implement very efficient co-located joins.
> >
>
> Hm... I don't think Ignite's approach for collocated joins is lees
> efficient. However, back to Spanner, the first value in the child table key
> is the parent table key. This tells me that Spanner collocates based on an
> approach very similar to Ignite's affinity key. Am I wrong?
>

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