Apache PIG 中是否有条件 IF 之类的运算符? [英] Is there any Conditional IF like operator in Apache PIG?

问题描述

实际上我正在编写 PIG 脚本，并且希望在满足其中一个条件时执行一些语句集.

我设置了一个变量并检查该变量的某个值.假设

if flag==0 thenA = LOAD 'file' using PigStorage() as (f1:int, ....);B = ...;C = ....;别的又是一些 Pig Latin 语句

我可以在 PIG Script 中执行此操作吗?如果是，那我该怎么做?

谢谢.

解决方案

是的，Pig 确实提供了 if-then-else 结构，但它没有按照您要求的方式使用.

Pig 的 if-then-else 是一个算术运算符 使用简写condition ? true_value : false_value"作为表达式的一部分调用，例如:

X = FOREACH A GENERATE f2, (f2==1?1:COUNT(B));

您必须已经加载了表 A 才能执行此操作.要围绕整个 Pig 语句执行控制流，您需要像 Fakrudeen 建议的 oozie 之类的东西.>

Actually I am writing PIG Script and want to execute some set of statements if one of the condition is satisfied.

I have set one variable and checking for some value of that variable. Suppose

if flag==0 then
  A = LOAD 'file' using PigStorage() as (f1:int, ....);
  B = ...;
  C = ....;
else 
  again some Pig Latin statements

Can I do this in PIG Script? If yes, then how can I do this?

Thanks.

解决方案

Yes, Pig does offer an if-then-else construction, but it is not used in the way you're asking.

Pig's if-then-else is an arithmetic operator invoked with the shorthand "condition ? true_value : false_value" as part of an expression, such as:

X = FOREACH A GENERATE f2, (f2==1?1:COUNT(B));

You have to already have loaded the table A to do this. To execute control flow around entire Pig statements you'll need something like oozie, as suggested by Fakrudeen.

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