[
https://issues.apache.org/jira/browse/IMPALA-10964?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17427586#comment-17427586
]
carolinchen commented on IMPALA-10964:
--------------------------------------
hi [~sql_forever] [~stigahuang]would you please check this feature, i want to
do this jiar
{code:java}
query_id: c74f23b8774947be:384a5f5300000000
query_status: Query Skew detected( c74f23b8774947be:384a5f5300000000) Threshold
is: 60. Skew found in EXCHANGE_NODE (id=9) terminated due to violation of
runtime execution constraints. The skew might affect cluster's ability to
support concurrency
{code}
> Add query option that limits skew query in runtime
> --------------------------------------------------
>
> Key: IMPALA-10964
> URL: https://issues.apache.org/jira/browse/IMPALA-10964
> Project: IMPALA
> Issue Type: Improvement
> Components: Backend
> Affects Versions: Impala 4.0.0
> Reporter: carolinchen
> Priority: Major
> Fix For: Impala 4.0.1
>
>
> Reject queries that skew value is too big when executing the query.
> Query skew refers to the situation in which some nodes are significantly
> behind other nodes in the process of concurrent execution of SQL.
> There are two style skews:
> 1. Row skew, which may be caused by unreasonable sql or uneven task
> distributions.
> 2. Time skew, which may be caused by different capability by execnode.
> Query skew will cause two effects:
> 1. For the skew node may execute slowly, which will slow down the query
> progress .
> 2. For the skew node may exhaust lots system resources( I/O, memory, rpc),
> which will
> affect other queries in the same host/ query pool.
> When the skew value reach unreasonale range, will affect the cluster status
> and other running queries. This is a mechanism to protect the cluster from
> potentially harmful queries(eg: mem_limit).
> In our environment, the SKEW_LIMIT query option is added to limit skewed
> query.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
