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From Andrey Mashenkov <andrey.mashen...@gmail.com>
Subject Re: Basic question on scaling of reads with ignite sql queries
Date Wed, 26 Apr 2017 11:42:41 GMT
Replicated cache works in different way. SQL query on replicated cache will
always run on single node.
Also, joins to replicated cache will always be local as all data is
collocated.

There is no way to run query in multiple threads on replicated cache as it
has single segment for now.


On Tue, Apr 25, 2017 at 1:07 PM, tuco.ramirez <rahul.babbar1@gmail.com>
wrote:

> Thanks Andrew for the explanation.
>
> Just one additional question. Lets say i have an apache ignite cluster
> running on 2 different machines, and we give noOfBackups of a replicated
> cache as 1, each of the 2 machines will hold 1/2 of the primary partitions
> and 1/2 of the backup partition.
>
> Currently, each SQL query runs on the primary partitions only, so that a
> query will be sent to 2 machines and the results will be merged.
> However in the above case, machine 1 has 1/2 of the primary partition and
> 1/2 of the backup partition of the machine 2(so that in a way, it holds all
> the data itself). Theoretically wouldn't it be faster if the query would
> hit
> only 1 node/machine since all the data would be on both the machines(in the
> above case).
>
> That was the rationale behind trying to see if the read from backups would
> help in case of SQL queries.
>
> May be, my understanding of this is incorrect.
>
> Thanks
> Tuco
>
>
>
>
>
> --
> View this message in context: http://apache-ignite-users.
> 70518.x6.nabble.com/Basic-question-on-scaling-of-reads-
> with-ignite-sql-queries-tp11975p12232.html
> Sent from the Apache Ignite Users mailing list archive at Nabble.com.
>



-- 
Best regards,
Andrey V. Mashenkov

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