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结果集归并的时候可以采用堆排序来提升性能 #161

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starmarine opened this issue Oct 26, 2016 · 1 comment
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结果集归并的时候可以采用堆排序来提升性能 #161

starmarine opened this issue Oct 26, 2016 · 1 comment
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type: duplicate type: enhancement

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@starmarine
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参考源码StreamingOrderByReducerResultSet.java
假如有10库，每库100表，取50个结果
如果采用遍历就是每次遍历1000个resultset，50个结果就是50000次
使用堆排序的话初始化时n_logn = 10000
剩下的50次就是50_logn = 500
总共10500次，还是有不小的性能提升
hanahmily pushed a commit that referenced this issue Jan 20, 2017
fix #215 #161 Improve streaming sort performance.
73fc752
@terrymanu
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duplicate with #215

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@terrymanu @starmarine