[PIG-3269] In operator support

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.11
• Fix Version/s: 0.12.0
• Component/s: internal-udfs, parser

Release Note

Pig now supports IN operator, and it can be used in any conditional expressions. For example,
bar = FILTER foo BY i IN ('a', 'b', 'c');

• Assignee: Cheolsoo Park
• Reporter: Cheolsoo Park
• Created: 07/Apr/13 23:05
• Updated: 16/Jun/16 22:09
• Resolved: 17/Apr/13 16:50

Description

This is another language improvement using the same approach as in PIG-3268.

Currently, Pig has no support for IN operator. To mimic it, users often have to concatenate several OR operators.

For example,

a = LOAD '1.txt' USING PigStorage(',') AS (i:int);
b = FILTER a BY 
   (i == 1) OR
   (i == 22) OR
   (i == 333) OR
   (i == 4444) OR
   (i == 55555);

But this can be re-rewritten in a more compact manner using IN operator as follows:

a = LOAD '1.txt' USING PigStorage(',') AS (i:int);
b = FILTER a BY i IN (1,22,333,4444,55555);

I propose that we implement IN operator in the following manner:

• Add built-in UDFs that take expressions as args. Take for example the aforementioned IN operator, we can define a UDF such as builtInUdf(i, 1, 22, 333, 4444, 55555).
• Add syntactical sugar for these built-in UDFs.

Issue Links

• is related to: PIG-3280 Document IN operator and CASE expression
• relates to: PIG-4931 Document IN operator
• relates to: PIG-3336 Change IN operator to use or-expressions instead of EvalFunc