Walkthrough

This PR modifies parquet export functionality to gracefully handle empty source tables. Changes include removing row count validation in the Rust schema layer, implementing per-partition empty detection and population in Java serialization, and adding tests verifying successful export of empty tables with proper schema.

Changes

Sequence Diagram(s)

sequenceDiagram
    participant Exporter as SerialParquetExporter
    participant PE as PartitionEncoder
    participant TR as TableReader
    participant Desc as PartitionDescriptor
    
    rect rgb(230, 245, 230)
    Note over Exporter: New Flow: Per-Partition Empty Handling
    
    Exporter->>Exporter: For each partition
    Exporter->>Exporter: Check if empty (openPartition <= 0)
    
    alt Partition Empty
        Exporter->>PE: populateEmptyPartition()
        PE->>TR: Get table metadata
        PE->>Desc: Set table name, timestamp index
        PE->>Desc: Populate metadata columns (non-zero types)
        PE-->>Exporter: Partition descriptor populated
    else Partition Not Empty
        Exporter->>PE: populateFromTableReader()
        PE-->>Exporter: Partition descriptor populated
    end
    
    Exporter->>Exporter: Mark CONVERTING_PARTITIONS → FINISHED
    Exporter->>Exporter: If no export result, MOVE_FILES → FINISHED
    end

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

• SerialParquetExporter.java: Logic flow restructuring from table-level to per-partition empty detection requires careful verification that the new status update sequence maintains correctness across all code paths (normal export, empty partitions, error handling).
• PartitionEncoder.java: New populateEmptyPartition() method needs review to confirm it correctly initializes schema for empty partitions with all supported column types and proper default values.
• Test updates: Verify that test expectations align with expected Parquet binary format and that the new test cases adequately cover empty table scenarios.

Suggested reviewers

• RaphDal

Pre-merge checks and finishing touches

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[PR Coverage check]

😍 pass : 23 / 23 (100.00%)

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