Sahil Takiar created IMPALA-9458:
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             Summary: Improve runtime profile counters for slow IO from remote 
stores
                 Key: IMPALA-9458
                 URL: https://issues.apache.org/jira/browse/IMPALA-9458
             Project: IMPALA
          Issue Type: Improvement
            Reporter: Sahil Takiar


Remote storage systems (e.g. cloud stores like S3 and ABFS) often have long 
tail latencies. Most I/O finishes relatively quickly, but some calls make take 
significantly longer. Even for HDFS, this is an issue (e.g. hedged reads were 
developed to help mitigate tail latencies, although no such feature exists for 
cloud storage connectors).

Currently, scan nodes just track the total amount of time spent reading data. 
It would be good to have a summary stats counter that tracks the min, avg, and 
max time spent reading data. This should at least allow us to identify when 
calls to remote storage services are taking longer than usual.



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