[PIG-3581] Incorrect scope resolution with nested foreach

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.13.0
• Assignee: Aniket Namadeo Mokashi
• Reporter: Venu Satuluri
• Created: 18/Nov/13 06:12
• Updated: 07/Jul/14 18:08
• Resolved: 26/Nov/13 19:23

Description

Consider the following script:

A = LOAD 'test_data' AS (a: int, b: int);
C = FOREACH A GENERATE *;
B = FOREACH (GROUP A BY a) {
	C = FILTER A BY b % 2 == 0;
	D = FILTER A BY b % 2 == 1;
	GENERATE group AS a, A.b AS every, C.b AS even, D.b AS odd;
};
DESCRIBE B;

Notice that C is defined both inside the nested foreach as well as outside. I would expect that in the GENERATE inside the nested FOREACH, the C that is used will be the one that is defined inside. If that is not so, I think at least a warning is due.

However, currently Pig silently assumes that the C you mean one is the one that is defined outside the nested FOREACH.

Hence, the result of "DESCRIBE B" looks as follows:

B: {
    a: int,
    every: {
        (
            b: int
        )
    },
    even: int,
    odd: {
        (
            b: int
        )
    }
}

If I remove the definition of C that is outside the foreach, then I get the following for "DESCRIBE B":

B: {
    a: int,
    every: {
        (
            b: int
        )
    },
    even: {
        (
            b: int
        )
    },
    odd: {
        (
            b: int
        )
    }
}

Issue Links

• breaks: PIG-3643 Nested Foreach with UDF and bincond is broken