Re: Scaling with SQL query

[Pavel Vinokurov <vi...@gmail.com>]

Hi Tom,

In case of a replicated cache the Ignite plans the execution of the sql
query across whole cluster by splitting into multiple map queries and a
single reduce query.
Thus it is possible communication overheads caused by  that the "reduce"
node collects data from multiple nodes.
Please show metrics for this query for you configuration.

Thanks,
Pavel


2018-06-26 6:24 GMT+03:00 Tom M <ta...@mail.com>:

> Hi,
>
> I have a cluster of 10 nodes, and a cache with replication factor 3 and no
> persistency enabled.
> The SQL query is pretty simple -- "SELECT * FROM Logs ORDER by time DESC
> LIMIT 100".
> I have checked the index for "time" attribute is applied.
>
> When I increase the number of nodes, throughput drops and latency
> increases.
> Can you please explain why and how Ignite processes this SQL request?
>



-- 

Regards

Pavel Vinokurov