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From 黄权隆 <>
Subject Question about the multi-thread scan node model
Date Wed, 30 Aug 2017 22:50:44 GMT
Hi all,

I’m working on applying our orc-support patch into the latest code bases (
IMPALA-5717 <>). Since our
patch is based on cdh-5.7.3-release which was released one year ago,
there’re lots of work to merge it.

One of the biggest changes from cdh-5.7.3-release I notice is the new scan
node & scanner model introduced in IMPALA-3902
<>. I think it’s inspired
by the investigating task in IMPALA-2849
<>, but I cannot find any
performance report in this issue. Could you share some report about this
multi-thread refactor?

I’m wondering how much this can improve the performance, since the old
single thread scan node & multi-thread scanners model has supplied
concurrent IO for reading, and most of the queries in OLAP are IO bound.



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