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https://issues.apache.org/jira/browse/IMPALA-4257?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tim Armstrong resolved IMPALA-4257.
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Resolution: Cannot Reproduce
> Parallel Queries fired from Cognos get stuck forever.
> -----------------------------------------------------
>
> Key: IMPALA-4257
> URL: https://issues.apache.org/jira/browse/IMPALA-4257
> Project: IMPALA
> Issue Type: Bug
> Components: Clients
> Affects Versions: Impala 2.5.0
> Environment: Dev
> Reporter: Deepak Nagar
> Priority: Major
> Labels: performance
> Attachments: profile (1).txt, profile (2).txt, profile (3).txt,
> profile (4).txt, profile (5).txt, profile (6).txt, profile (7).txt, profile
> (7).txt
>
>
> We are using cloudera Impala 2.5.0 and created Parquet table (snappy
> compression). These tables are being accessed by Cognos 10.2 version for
> generating the reports and cognos 10.2 runs the queries in Dynamic Query Mode
> (Dynamic Query Mode introduces the concept of a memory-resident data cache in
> cognos. The query engine ultimately issue SQL code against the database in
> order to populate the cache, only minimal and simplified queries are issued
> against the database). These simplified queries are however fired to Impala
> in parallel.
> The parallel execution of these queries seems to slowing down the whole
> process and most of the queries (6 out of 8 fired in parallel in our case)
> never finish, they run for days. The same set of queries when run
> individually in sequence take only few seonds to complete.
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