---
phase: 53-yaml-file-loading
plan: 01
subsystem: database
tags: [duckdb, yaml, ffi, c-api, parser-hooks, file-io, security]

requires:
  - phase: 52-yaml-ddl-integration
    provides: FROM YAML $$ inline syntax, dollar-quote extraction, YAML-to-JSON rewrite pipeline
provides:
  - FROM YAML FILE '/path' syntax for creating semantic views from external YAML files
  - Sentinel protocol (__SV_YAML_FILE__) for Rust-to-C++ file loading communication
  - DuckDB read_text() integration for security-enforced file reading
  - Tagged dollar-quoting ($__sv_file$) to prevent YAML content collision
affects: [yaml-materialization, documentation, examples]

tech-stack:
  added: []
  patterns: [sentinel-protocol-ffi, two-phase-file-loading, tagged-dollar-quoting]

key-files:
  created: [test/sql/phase53_yaml_file.test]
  modified: [src/parse.rs, cpp/src/shim.cpp, test/sql/TEST_LIST]

key-decisions:
  - "Used \\x01 (SOH) separator instead of \\x00 (NUL) in sentinel because sentinel passes through C string APIs that treat NUL as terminator"
  - "Placed enable_external_access security test last in sqllogictest because the setting cannot be re-enabled within the same test file"
  - "Used tagged dollar-quote $__sv_file$ instead of bare $$ to prevent collision with YAML content containing $$"

patterns-established:
  - "Sentinel protocol: Rust returns __SV_YAML_FILE__ sentinel, C++ intercepts and acts before executing"
  - "Two-phase file loading: detect syntax in Rust parse layer, read file in C++ bind layer via read_text()"

requirements-completed: [YAML-02, YAML-07]

duration: 61min
completed: 2026-04-19
---

# Phase 53: YAML File Loading Summary

**Two-layer file loading via sentinel protocol: Rust detects FROM YAML FILE syntax, C++ reads file via DuckDB read_text() with automatic enable_external_access enforcement**

## Performance

- **Duration:** ~61 min (across rate limit pause)
- **Started:** 2026-04-18T22:30:00Z
- **Completed:** 2026-04-19T00:00:00Z
- **Tasks:** 2
- **Files modified:** 4

## Accomplishments
- `CREATE SEMANTIC VIEW name FROM YAML FILE '/path/to/file.yaml'` creates queryable semantic views from external YAML files
- Security enforced automatically: `SET enable_external_access = false` blocks FROM YAML FILE via DuckDB's read_text() built-in
- All DDL variants work with FROM YAML FILE: CREATE, CREATE OR REPLACE, CREATE IF NOT EXISTS, with COMMENT
- 14 unit tests + 13 integration tests (32/32 sqllogictest suite passes)

## Task Commits

Each task was committed atomically:

1. **Task 1: Rust FROM YAML FILE parsing + sentinel generation** - `4d04c6c` (feat)
2. **Task 2: C++ file reading via read_text() + sqllogictest integration** - `325d2f5` (feat)

## Files Created/Modified
- `src/parse.rs` - Added extract_single_quoted(), rewrite_ddl_yaml_file_body(), FROM YAML FILE detection branch in validate_create_body(), 14 unit tests
- `cpp/src/shim.cpp` - Added __SV_YAML_FILE__ sentinel interception in sv_ddl_bind, read_text() file loading, tagged dollar-quote reconstruction, dynamic buffer sizing
- `test/sql/phase53_yaml_file.test` - Integration tests: basic load, CREATE OR REPLACE, IF NOT EXISTS, COMMENT, case-insensitive, security, error cases, inline regression
- `test/sql/TEST_LIST` - Added phase53_yaml_file.test entry

## Decisions Made
- Changed sentinel separator from \x00 (NUL) to \x01 (SOH) — NUL terminates C strings, corrupting the sentinel when passed through sv_rewrite_ddl_rust FFI buffer. Discovered during Task 2 integration testing.
- Moved security test (enable_external_access=false) to end of test file — the setting cannot be re-enabled in the same DuckDB session, so it must be the final test case.
- Used `SELECT content FROM read_text(...)` projection (column 0 after projection) instead of `duckdb_value_varchar(&result, 1, 0)` (column 1 of full schema) to avoid off-by-one column index errors.

## Deviations from Plan

### Auto-fixed Issues

**1. Sentinel separator change (\x00 → \x01)**
- **Found during:** Task 2 (C++ integration)
- **Issue:** NUL bytes in sentinel string were being treated as C string terminators, truncating the sentinel before kind/name/comment fields
- **Fix:** Changed separator to \x01 (SOH control character) in both Rust (rewrite_ddl_yaml_file_body) and C++ (sv_ddl_bind sentinel parser)
- **Files modified:** src/parse.rs, cpp/src/shim.cpp
- **Verification:** All 14 unit tests + 13 integration tests pass
- **Committed in:** 325d2f5

---

**Total deviations:** 1 auto-fixed (sentinel separator)
**Impact on plan:** Essential fix for correctness. No scope creep.

## Issues Encountered
- Rate limit hit before SUMMARY.md creation — resumed and completed manually

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- FROM YAML FILE syntax fully functional with security enforcement
- Ready for Phase 54 (YAML materialization routing) or documentation updates

---
*Phase: 53-yaml-file-loading*
*Completed: 2026-04-19*
