fix: preserve num field in AlterTableCmd 14->15 transformation

[pyramation]

Fix: preserve num field in AlterTableCmd 14->15 transformation

Summary

Fixed an AST transformation mismatch where the num field was being dropped during PostgreSQL 14 to 15 AST transformation for ALTER INDEX statements. The issue occurred in the AlterTableCmd transformation method which was explicitly preserving only certain fields but missing the num field.

Root cause: The AlterTableCmd method in v14-to-v15.ts had conditional field preservation logic but was missing handling for the num field, causing it to be dropped during transformation even though both PG14 and PG15 should have identical AST structures for this statement type.

Changes made:

• Added num field preservation in AlterTableCmd transformation method
• Enabled the previously skipped test case latest/postgres/create_index-345.sql

Review & Testing Checklist for Human

• Run the specific test case - Verify yarn test __tests__/kitchen-sink/14-15/latest-postgres-create_index.test.ts passes and specifically tests the SQL ALTER INDEX concur_exprs_index_expr ALTER COLUMN 1 SET STATISTICS 100
• Check for other missing fields - Review the AlterTableCmd method to ensure no other fields are missing from the transformation logic (compare against PG14/PG15 type definitions)
• Run full test suite - Execute yarn test to ensure no regressions were introduced by preserving this field
• Verify pattern consistency - Confirm the added num field handling follows the same conditional preservation pattern as other fields in the method

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    TestFile["__tests__/kitchen-sink/14-15/latest-postgres-create_index.test.ts"]:::context
    SQL["ALTER INDEX ... ALTER COLUMN 1 SET STATISTICS 100"]:::context
    SkipList["test-utils/skip-tests/transformer-errors.ts"]:::minor-edit
    Transformer["src/transformers/v14-to-v15.ts:AlterTableCmd()"]:::major-edit
    
    TestFile --> SQL
    SQL --> Transformer
    SkipList -.-> TestFile
    
    Transformer --> |"Before: drops 'num' field"| BadAST["AST missing 'num': 1"]:::context
    Transformer --> |"After: preserves 'num' field"| GoodAST["AST with 'num': 1"]:::context
    
    subgraph Legend
        L1["Major Edit"]:::major-edit
        L2["Minor Edit"]:::minor-edit  
        L3["Context/No Edit"]:::context
    end
    

    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

• Link to Devin run: https://app.devin.ai/sessions/d1e90b8732e442abb6e87fc552d91eb0
• Requested by: Dan Lynch (@pyramation)
• Testing approach: Used debugging scripts to isolate the transformation issue and verify the fix works correctly
• Risk level: Low - targeted fix following established patterns, but reviewer should verify completeness of field handling

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