Support mvdedup eval function

[ahkcs]

---

Description

This PR implements the mvdedup eval function for PPL, enabling users to remove duplicate values from multivalue arrays.

---

Behavior

Given the input:

source=index | eval result = mvdedup(array(1, 2, 2, 3, 1, 4))

The function returns:

[1, 2, 3, 4]

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Key Details

• Empty arrays return empty arrays

• Order-preserving: The first appearance of each value is kept; subsequent duplicates are removed.

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Example

Input	Output
array(1, 2, 2, 3, 1, 4)	[1, 2, 3, 4]
array()	[]

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]

Could you check if this has same semantic as ARRAY_DISTINCT?

2: jdbc:calcite:model=src/test/resources/mode> SELECT ARRAY_DISTINCT(ARRAY[1,2,1,3,3,4]);
+--------------+
|    EXPR$0    |
+--------------+
| [1, 2, 3, 4] |
+--------------+
1 row selected (0.018 seconds)

2: jdbc:calcite:model=src/test/resources/mode> SELECT ARRAY_DISTINCT(ARRAY[4,1,2,1,3,3,4]);
+--------------+
|    EXPR$0    |
+--------------+
| [4, 1, 2, 3] |
+--------------+

[ahkcs]

Could you check if this has same semantic as ARRAY_DISTINCT?

Hi @dai-chen, thanks for the suggestion! After checking, I think ARRAY_DISTINCT is suitable for our implementation for mvdedup eval function, I have updated the implementation to remove the UDF and use ARRAY_DISTINCT for implementation.

cc @ykmr1224

[dai-chen]

Thanks for the changes!

[dai-chen]

Do we need to backport?

[ahkcs]

Do we need to backport?

Yes