---
phase: 11.1-review-possible-ddl-and-query-syntax-options-and-bring-it-as-close-as-we-can-to-snowflake-semantic-views
plan: "02"
subsystem: database
tags: [rust, parser, ddl, struct-list, semantic-views, tdd]

requires:
  - phase: 11.1-01
    provides: "TableRef, JoinColumn, Join.join_columns, SemanticViewDefinition.tables"

provides:
  - "parse_define_args() reads 6 typed VScalar columns into SemanticViewDefinition"
  - "validate_granularity() pure helper with 4 unit tests"
  - "read_str() unsafe helper for duckdb_string_t extraction"

affects:
  - "11.1-04 (define.rs invokes parse_define_args in its invoke() method)"

tech-stack:
  added: []
  patterns:
    - "ddl module is #[cfg(feature = extension)] gated — tests run via cargo test --features extension"
    - "parse_args unit tests cover only pure helpers (validate_granularity) — parse_define_args is validated end-to-end via sqllogictest"

key-files:
  created:
    - "src/ddl/parse_args.rs"
  modified:
    - "src/ddl/mod.rs"

key-decisions:
  - "parse_args.rs kept in ddl/ module (extension feature gated) — reuses duckdb::core and libduckdb_sys already available"
  - "Unit tests target only pure helpers (validate_granularity, read_str) — DataChunkHandle construction not feasible without full DuckDB runtime"
  - "ParsedDefineArgs is a thin wrapper struct (name + def) for clean return type"

patterns-established:
  - "parse_define_args pattern: list_vector(col).len() + struct_child(len) + child(field, len) + get_entry(row) for offset/length"
  - "Nested list pattern: rel_struct.list_vector_child(2) for join_columns nested in relationships"

requirements-completed:
  - DDL-04

duration: 10min
completed: 2026-03-02
---

# Phase 11.1 Plan 02: parse_args.rs STRUCT/LIST Parser Summary

**parse_define_args() reads all 6 typed VScalar columns into SemanticViewDefinition; 4 unit tests for validate_granularity pass**

## Performance

- **Duration:** 10 min
- **Started:** 2026-03-02T00:40:00Z
- **Completed:** 2026-03-02T00:50:00Z
- **Tasks:** 1
- **Files modified:** 2

## Accomplishments
- Created `src/ddl/parse_args.rs` with the full 6-column VScalar parser:
  - Column 0: name (VARCHAR)
  - Column 1: tables `LIST(STRUCT(alias, table))`
  - Column 2: relationships `LIST(STRUCT(from_table, to_table, join_columns LIST(STRUCT(from, to))))`
  - Column 3: dimensions `LIST(STRUCT(name, expr, source_table))`
  - Column 4: time_dimensions `LIST(STRUCT(name, expr, granularity))` with granularity validation
  - Column 5: metrics `LIST(STRUCT(name, expr, source_table))`
- Added `validate_granularity()` pure helper with `VALID_GRANULARITIES` constant
- Added `read_str()` unsafe helper for `duckdb_string_t` extraction
- Added `pub mod parse_args;` to `src/ddl/mod.rs`
- 4 unit tests in `granularity_validation_tests` submodule — all pass via `cargo test --features extension`

## Task Commits

1. **Task 1: Implement parse_args.rs** - `392515f` (feat)

## Files Created/Modified
- `src/ddl/parse_args.rs` - Full STRUCT/LIST VScalar parser with unit tests
- `src/ddl/mod.rs` - Added `pub mod parse_args;`

## Decisions Made
- Tests only cover pure helpers — `DataChunkHandle` cannot be constructed in unit tests without a live DuckDB runtime; full integration coverage via sqllogictest in Plan 11.1-05
- `ddl` module is feature-gated under `extension`; tests require `cargo test --features extension` to compile and run
- `ParsedDefineArgs { name, def }` is a minimal wrapper for clean return type from the parsing function

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Formatting] cargo fmt reformatted import order and assert! calls**
- **Found during:** Commit (pre-commit hook ran cargo fmt)
- **Issue:** Import `JoinColumn` was ordered before `Join` in use statement; some assert! calls and the `base_table` chain needed reformatting
- **Fix:** Applied `cargo fmt` explicitly to the file before committing
- **Files modified:** src/ddl/parse_args.rs
- **Verification:** Pre-commit hook passed on second attempt
- **Committed in:** 392515f

---

**Total deviations:** 1 auto-fixed (formatting)
**Impact on plan:** None — only style changes.

## Issues Encountered
None

## Next Phase Readiness
- `parse_define_args` is ready to be called from `define.rs` `invoke()` in Plan 04
- Wave 3 (Plan 11.1-04) can proceed

---
*Phase: 11.1-review-possible-ddl-and-query-syntax-options-and-bring-it-as-close-as-we-can-to-snowflake-semantic-views*
*Completed: 2026-03-02*
