从Physical Plan到Map-Reduce Plan 注:由于我们重点关注的是Pig On Spark针对RDD的运行计划,所以Pig物理运行计划之后的后端參考意义不大,这些部分主要分析流程,忽略实现细节. 入口类MRCompiler,MRCompilier依照拓扑顺序遍历物理运行计划中的节点,将其转换为MROperator,每一个MROperator都代表一个map-reduce job,整个完整的计划存储在MROperPlan类中.当中针对Load和Store操作会做下面特殊处理:…
本文是Pig系统分析系列中的最后一篇了,主要讨论怎样扩展Pig功能.不仅介绍Pig本身提供的UDFs扩展机制,还从架构上探讨Pig扩展可能性. 补充说明:前些天同事发现twitter推动的Pig On Spark项目:Spork,准备研究下. UDFs 通过UDFs(用户自己定义函数),能够自己定义数据处理方法,扩展Pig功能.实际上,UDFS除了使用之前须要register/define外.和内置函数没什么不同. 主要的EvalFunc 以内置的ABS函数为例: public class AB…
grunt> cat t.txt kw1 2 kw3 1 kw2 4 kw1 5 kw2 2 cat test.pig A = LOAD '/user/input/t.txt' as (k:chararray,c:int); B = group A BY k; C = foreach B generate group,SUM(A.c); -- DUMP C; store C into 'test.output'; $ pig -e 'illustrate -script test.pig' 20…
From http://blog.csdn.net/wujiandao/article/details/6621073 1. Four ways to get execution plan(anytime you want, for specified sql) • Execute the SQL statement EXPLAIN PLAN, and then query the table where the output was written. • Query a dynamic per…
What is a Test Plan? A TEST PLAN is a detailed document that describes the test strategy, objectives, schedule, estimation and deliverables and resources required for testing. Test Plan helps us determine the effort needed to validate the quality of…
前两天使用pig做ETL,粗浅的看了一下,没有系统地学习,感觉pig还是值得学习的,故又重新看programming pig. 以下是看的第一章的笔记: What is pig? Pig provides an engine for executing data flows in parallel on Hadoop. It includes a language, Pig Latin, for expressing these data flows. Pig Latin includes op…
"I need a project plan by tomorrow morning." As project managers, that's what we hear. But we know that what the boss usually means is that s/he wants a project schedule. There is a problem though, how can you come up with a schedule without hav…
在11g之前版本,提供了stored outlines(sql概要)特性来保存sql的执行计划. 在11g中,引入了一个新的特性sql计划管理(sql plan management)特性来保存sql性能. 数据库自动控制sql执行计划的演变,借助sql plan baselines. SPM会不时的捕获和评估sql的执行计划,然后建立只包含高效的执行计划的sql plan baselines. sql plan baselines只会包含那些不会引起sql性能下降的执行计划. 当系统遇到以下变…