Tim Armstrong created IMPALA-9015:
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Summary: Use better algorithm for allocating scan ranges to
finstances within a daemon in schedule
Key: IMPALA-9015
URL: https://issues.apache.org/jira/browse/IMPALA-9015
Project: IMPALA
Issue Type: Sub-task
Components: Distributed Exec
Reporter: Tim Armstrong
Assignee: Tim Armstrong
Currently the scheduler uses a single-pass algorithm to allocate scan ranges to
nodes. It has several deficiencies:
* It doesn't guarantee that the desired number of instances are created. E.g.
if mt_dop is 4, there are 3 impalads and 9 scan ranges, it should create 3
instances per impala but doesn't reliably.
* It tends to over-allocate to the first instances it visits.
* The result depends quite a bit on the input order of the scan ranges.
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