Greptile Overview

Greptile Summary

This PR implements comparison operations (==, !=, <, <=, >, >=, <=>) for List, FixedSizeList, and Struct data types in Daft. The implementation includes a performance optimization using Arrow's row-based comparison when applicable, with automatic fallback to element-wise comparison.

Key Changes:

• Moved Operator enum from daft-dsl to daft-core for reuse in array operations
• Improved Operator categorization with new helper methods (is_equality, is_ordering, is_logical)
• Implemented row-based comparison optimization using arrow-row::RowConverter for supported types without nulls or floats
• Added element-wise comparison logic for lists (lexicographic ordering) and structs (field-by-field comparison)
• List comparison uses lexicographic ordering with length as tiebreaker
• Struct comparison compares fields in schema order
• Comprehensive test coverage for new comparison operations including null-safe comparisons

Minor Issue:

• The is_comparison() method definition changed from the old implementation - it previously included logical operators (And, Or, Xor) but now correctly excludes them. This is more accurate but worth verifying no code relied on the old behavior.

Confidence Score: 4/5

• This PR is generally safe to merge with one minor behavioral change to verify
• The implementation is well-structured with comprehensive test coverage, proper optimization strategy, and correct null handling. The refactoring of Operator to daft-core is clean and all imports are properly updated. The one concern is the subtle behavior change in is_comparison() which previously included logical operators but now excludes them (which is more accurate). Score is 4/5 due to this behavioral change that should be verified.
• Check src/daft-core/src/operator.rs for the is_comparison() behavior change impact

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant User
    participant Series
    participant ListArray
    participant RowFastPath
    participant ElementWise
    participant RowConverter

    User->>Series: compare(lhs, rhs, op)
    Series->>Series: Check if List/FixedSizeList/Struct type
    alt List/FixedSizeList/Struct
        Series->>ListArray: compare_list_like_array(lhs, rhs, op)
        ListArray->>ListArray: comparison_broadcast_info()
        ListArray->>RowFastPath: row_fast_path()?
        
        alt No nulls + No floats + Supported type
            RowFastPath->>RowFastPath: type_contains_float() → false
            RowFastPath->>RowFastPath: array_has_any_nulls() → false
            RowFastPath->>RowConverter: convert_columns()
            RowConverter-->>RowFastPath: row representations
            RowFastPath->>RowFastPath: Compare rows using cmp()
            RowFastPath-->>ListArray: Some(BooleanArray)
            ListArray-->>Series: BooleanArray
        else Contains nulls/floats or unsupported
            RowFastPath-->>ListArray: None (fallback)
            ListArray->>ElementWise: compare_list_like_value() per element
            loop For each array index
                ElementWise->>ElementWise: Get element at index
                ElementWise->>Series: compare_scalar_series()
                Series-->>ElementWise: Option<bool>
            end
            ElementWise-->>ListArray: BooleanArray
            ListArray-->>Series: BooleanArray
        end
    else Primitive types
        Series->>Series: Use existing comparison logic
    end
    Series-->>User: BooleanArray result

Codecov Report

❌ Patch coverage is 67.60563% with 138 lines in your changes missing coverage. Please review.
✅ Project coverage is 43.26%. Comparing base (e7adf06) to head (005c55c).
⚠️ Report is 12 commits behind head on main.

@@            Coverage Diff             @@
##             main    #6104      +/-   ##
==========================================
- Coverage   43.34%   43.26%   -0.09%     
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  Files         917      921       +4     
  Lines      112995   114222    +1227     
==========================================
+ Hits        48978    49417     +439     
- Misses      64017    64805     +788