Fix: map_from_arrays() with NULL inputs causes native crash

[kazantsev-maksim]

Which issue does this PR close?

Closes #3327

Rationale for this change

What changes are included in this PR?

How are these changes tested?

Tested with existing unit tests

[andygrove]

This should be fully native?

Suggested change

	query spark_answer_only
	query

[andygrove]

Could you also add tests where v is NULL?

[kazantsev-maksim]

I think it will be the same behavior: in the original data, value == null when key == null.

statement
INSERT INTO test_map_from_arrays VALUES (array('a', 'b', 'c'), array(1, 2, 3)), (array(), array()), (NULL, NULL)

[andygrove]

I ran some additional tests locally and found that the null check needs to cover both inputs, not just the keys. The Spark docs say map_from_arrays "returns null if either the keys array or values array is null", but the current keyIsNotNullExpr only checks expr.left.

I added the row (array('x'), NULL) to the test data and a query SELECT map_from_arrays(k, v) FROM test_map_from_arrays WHERE k IS NOT NULL AND v IS NULL, which crashes with CometNativeException: Compute error: concat requires input of at least one array.

Here's a suggested updated test file that covers the missing cases. Note that I did use AI to generate these tests, so it is possible that there are mistakes.

-- ConfigMatrix: parquet.enable.dictionary=false,true

statement
CREATE TABLE test_map_from_arrays(k array<string>, v array<int>) USING parquet

statement
INSERT INTO test_map_from_arrays VALUES
  (array('a', 'b', 'c'), array(1, 2, 3)),
  (array(), array()),
  (NULL, NULL),
  (array('x'), NULL),
  (NULL, array(99))

-- basic functionality
query spark_answer_only
SELECT map_from_arrays(k, v) FROM test_map_from_arrays WHERE k IS NOT NULL AND v IS NOT NULL

-- both inputs NULL should return NULL
query
SELECT map_from_arrays(k, v) FROM test_map_from_arrays WHERE k IS NULL AND v IS NULL

-- keys not null but values null should return NULL (Spark behavior)
query
SELECT map_from_arrays(k, v) FROM test_map_from_arrays WHERE k IS NOT NULL AND v IS NULL

-- keys null but values not null should return NULL (Spark behavior)
query
SELECT map_from_arrays(k, v) FROM test_map_from_arrays WHERE k IS NULL AND v IS NOT NULL

-- all rows including nulls
query spark_answer_only
SELECT map_from_arrays(k, v) FROM test_map_from_arrays

-- literal arguments
query spark_answer_only
SELECT map_from_arrays(array('a', 'b'), array(1, 2))

-- literal null arguments
query
SELECT map_from_arrays(NULL, array(1, 2))

query
SELECT map_from_arrays(array('a'), NULL)

query
SELECT map_from_arrays(NULL, NULL)

To fix the serde, the condition should check both inputs for null. Something like IsNotNull(expr.left) AND IsNotNull(expr.right) instead of just IsNotNull(expr.left).

[kazantsev-maksim]

Tanks @andygrove, fixed this.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.03%. Comparing base (f09f8af) to head (d82900a).
⚠️ Report is 927 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3356      +/-   ##
============================================
+ Coverage     56.12%   60.03%   +3.91%     
- Complexity      976     1477     +501     
============================================
  Files           119      175      +56     
  Lines         11743    16178    +4435     
  Branches       2251     2681     +430     
============================================
+ Hits           6591     9713    +3122     
- Misses         4012     5114    +1102     
- Partials       1140     1351     +211     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.