Support mvzip eval function

[ahkcs]

Description

The mvzip function combines values from two multivalue fields pairwise with a delimiter.
It stitches together corresponding elements from each field, similar to Python’s zip() function.

The function supports two modes of operation:

1. Default delimiter:

   mvzip(mv_left, mv_right)
   

   Combines fields using a comma (,) as the default delimiter.

2. Custom delimiter:

   mvzip(mv_left, mv_right, delimiter)
   

   Combines fields using the specified delimiter.

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Key Features

• Pairwise combination: Combines 1st element of left with 1st of right, 2nd with 2nd, etc.
• Stops at shorter length: Processing stops at the length of the shorter field (Python zip() behavior).
• Scalar handling: Treats scalar values as single-element arrays.
• Null handling: Returns null if either input is null.
• Default delimiter: Uses comma (,) when delimiter is not specified.

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Usage Examples

Basic Usage with Default Delimiter

source=people 
| eval hosts = array('host1', 'host2'), ports = array(80, 443), nserver = mvzip(hosts, ports) 
| fields nserver
# Returns: [host1,80, host2,443]

source=accounts 
| eval result = mvzip(firstname, lastname) 
| fields result
# Returns: [Amber,Duke]

---

Custom Delimiter

source=people 
| eval arr1 = array('a', 'b', 'c'), arr2 = array('x', 'y', 'z'), result = mvzip(arr1, arr2, '|') 
| fields result
# Returns: [a|x, b|y, c|z]

source=accounts 
| eval result = mvzip(firstname, lastname, ' ') 
| fields result
# Returns: [Amber Duke]

---

Different Length Arrays

source=people 
| eval arr1 = array(1, 2, 3), arr2 = array('a', 'b'), result = mvzip(arr1, arr2) 
| fields result
# Returns: [1,a, 2,b]
# Note: Stops at length of shorter array

---

Nested mvzip Calls

source=people 
| eval field1 = array('a', 'b'), field2 = array('c', 'd'), field3 = array('e', 'f'), result = mvzip(mvzip(field1, field2, '|'), field3, '|') 
| fields result
# Returns: [a|c|e, b|d|f]

---

Null Handling

source=people 
| eval result = mvzip(nullif(1, 1), array('test')) 
| fields result
# Returns: null

Check List

• New functionality includes testing.
• New functionality has been documented.
• New functionality has javadoc added.
• New functionality has a user manual doc added.
• New PPL command checklist all confirmed.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff or -s.
• Public documentation issue/PR created.

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[dai-chen]

QQ: can SQL's ARRAYS_ZIP be used for this?

[ahkcs]

QQ: can SQL's ARRAYS_ZIP be used for this?

Thanks for the question! I considered ARRAYS_ZIP but it's not suitable for mvzip due to semantic differences:

1. Return Type:
   - ARRAYS_ZIP → ARRAY (e.g., [STRUCT(0:'a', 1:'x'), STRUCT(0:'b', 1:'y')])
   - mvzip → ARRAY (e.g., ['a|x', 'b|y'])
2. Delimiter Requirement:
   - mvzip requires custom delimiter support for string concatenation
   - ARRAYS_ZIP creates structured data without string formatting