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From Carol McDonald <cmcdon...@maprtech.com>
Subject Re: Questions on drill execution
Date Mon, 04 May 2015 14:10:05 GMT
https://cwiki.apache.org/confluence/display/DRILL/EXPLAIN+Commands

On Mon, May 4, 2015 at 3:46 AM, George Lu <luwenbin888@gmail.com> wrote:

> Dear all,
>
> I have deployed Drill on several nodes in the cluster and experienced the
> query.
> I have some questions:
>
> 1) Can anyone show me some links to read for the Drill execution plan, how
> to understand it.
>
> 2) I execute some group by query on HBase several times, some time very
> fast, while sometimes very slow, and even get exception, like "Query
> failed: RemoteRpcException: Failure while running fragment., Command failed
> while establishing connection.  Failure type CONNECTION. [
> 2ba2092f-53ed-480a-9f23-f89b6e6a91a0 on test6:31010 ]
> [ 2ba2092f-53ed-480a-9f23-f89b6e6a91a0 on test6:31010 ]
>
>
> java.lang.RuntimeException: java.sql.SQLException: Failure while executing
> query.
> at sqlline.SqlLine$IncrementalRows.hasNext(SqlLine.java:2514)
> at sqlline.SqlLine$TableOutputFormat.print(SqlLine.java:2148)
> at sqlline.SqlLine.print(SqlLine.java:1809)
> at sqlline.SqlLine$Commands.execute(SqlLine.java:3766)
> at sqlline.SqlLine$Commands.sql(SqlLine.java:3663)
> at sqlline.SqlLine.dispatch(SqlLine.java:889)
> at sqlline.SqlLine.begin(SqlLine.java:763)
> at sqlline.SqlLine.start(SqlLine.java:498)
> at sqlline.SqlLine.main(SqlLine.java:460)"
>
> I am not sure whether Drill uses pre-execute like in Hadoop or auto failure
> detection. If some of the execution node failed, what will happen? If some
> node is under high pressure for other task, and what will happen if this
> node becomes the one who drags the whole execution slow?
>
> Thanks!
>
> George
>

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