Feature/enhance schema rule

.gitignore

@@ -79,3 +79,7 @@ site/
 
 # Cursor
 .cursor/
+
+# Claude Code
+CLAUDE.md
+.claude/

CHANGELOG.md

@@ -19,6 +19,43 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Removed
 - None
 
+## [0.4.3] - 2025-09-06
+
+### Added
+- feat(schema): Enhanced SCHEMA rule with metadata validation capabilities
+- feat(schema): String length validation via `max_length` parameter for precise VARCHAR constraints
+- feat(schema): Float precision and scale validation via `precision`/`scale` parameters for DECIMAL constraints
+- feat(cli): Extended JSON schema format support with metadata fields (max_length, precision, scale)
+- feat(core): Database-agnostic metadata extraction across MySQL, PostgreSQL, and SQLite
+- feat(core): Vendor-specific type parsing with regex-based metadata extraction
+- feat(core): Performance-optimized validation using database catalog queries (no data scanning)
+- feat(validation): Comprehensive metadata comparison logic with detailed failure reporting
+- feat(cli): Enhanced rule parameter validation for metadata fields with logical constraints
+- feat(tests): Comprehensive metadata validation test suite (87% coverage on SchemaExecutor)
+- feat(tests): Unit, integration, and CLI tests for metadata validation scenarios
+- feat(docs): Enhanced documentation with metadata validation examples and troubleshooting guide
+- feat(docs): Migration guide for legacy schema formats and performance characteristics
+
+### Changed
+- refactor(schema): Enhanced SchemaExecutor with metadata validation capabilities
+- refactor(cli): Extended CLI schema parsing to support metadata fields with validation
+- refactor(core): Improved database metadata extraction and type mapping
+- improve(performance): Metadata validation uses single database query per table (no data scans)
+- improve(validation): Enhanced error messages with specific metadata mismatch descriptions
+- improve(architecture): Clear separation between structure validation (SCHEMA) and content validation (RANGE/ENUM)
+
+### Fixed
+- None
+
+### Removed
+- None
+
+### Migration Guide
+- **Backward Compatibility**: Existing schema files without metadata continue to work unchanged
+- **Enhanced Validation**: Add `max_length`, `precision`, and `scale` fields incrementally to existing schemas
+- **Performance**: Metadata validation provides superior performance vs scanning-based approaches
+- **Architecture**: Enhanced SCHEMA rule eliminates need for separate LENGTH rule type
+
 ## [0.4.2] - 2025-08-27
 
 ### Added

README.md

@@ -72,6 +72,166 @@ Set up validation checkpoints at various stages of your data pipelines to guaran
 vlite schema --conn "mysql://user:pass@host:3306/sales" --rules customers_schema.json
 ```
 
+### Advanced Schema Examples
+
+**Multi-Table Validation:**
+```json
+{
+  "customers": {
+    "rules": [
+      { "field": "id", "type": "integer", "required": true },
+      { "field": "name", "type": "string", "required": true },
+      { "field": "email", "type": "string", "required": true },
+      { "field": "age", "type": "integer", "min": 18, "max": 100 }
+    ],
+    "strict_mode": true
+  },
+  "orders": {
+    "rules": [
+      { "field": "id", "type": "integer", "required": true },
+      { "field": "customer_id", "type": "integer", "required": true },
+      { "field": "total", "type": "float", "min": 0 },
+      { "field": "status", "enum": ["pending", "completed", "cancelled"] }
+    ]
+  }
+}
+```
+
+**CSV File Validation:**
+```bash
+# Validate CSV file structure
+vlite schema --conn "sales_data.csv" --rules csv_schema.json --output json
+```
+
+**Complex Data Types:**
+```json
+{
+  "events": {
+    "rules": [
+      { "field": "timestamp", "type": "datetime", "required": true },
+      { "field": "event_type", "enum": ["login", "logout", "purchase"] },
+      { "field": "user_id", "type": "string", "required": true },
+      { "field": "metadata", "type": "string" }
+    ],
+    "case_insensitive": true
+  }
+}
+```
+
+**Available Data Types:**
+- `string` - Text data (VARCHAR, TEXT, CHAR)
+- `integer` - Whole numbers (INT, BIGINT, SMALLINT)
+- `float` - Decimal numbers (FLOAT, DOUBLE, DECIMAL)
+- `boolean` - True/false values (BOOLEAN, BOOL, BIT)
+- `date` - Date only (DATE)
+- `datetime` - Date and time (DATETIME, TIMESTAMP)
+
+### Enhanced Schema Validation with Metadata
+
+ValidateLite now supports **metadata validation** for precise schema enforcement without scanning table data. This provides superior performance by validating column constraints directly from database metadata.
+
+**Metadata Validation Features:**
+- **String Length Validation**: Validate `max_length` for string columns
+- **Float Precision Validation**: Validate `precision` and `scale` for decimal columns
+- **Database-Agnostic**: Works across MySQL, PostgreSQL, and SQLite
+- **Performance Optimized**: Uses database catalog queries, not data scans
+
+**Enhanced Schema Examples:**
+
+**String Metadata Validation:**
+```json
+{
+  "users": {
+    "rules": [
+      {
+        "field": "username",
+        "type": "string",
+        "max_length": 50,
+        "required": true
+      },
+      {
+        "field": "email",
+        "type": "string",
+        "max_length": 255,
+        "required": true
+      },
+      {
+        "field": "biography",
+        "type": "string",
+        "max_length": 1000
+      }
+    ]
+  }
+}
+```
+
+**Float Precision Validation:**
+```json
+{
+  "products": {
+    "rules": [
+      {
+        "field": "price",
+        "type": "float",
+        "precision": 10,
+        "scale": 2,
+        "required": true
+      },
+      {
+        "field": "weight",
+        "type": "float",
+        "precision": 8,
+        "scale": 3
+      }
+    ]
+  }
+}
+```
+
+**Mixed Metadata Schema:**
+```json
+{
+  "orders": {
+    "rules": [
+      { "field": "id", "type": "integer", "required": true },
+      {
+        "field": "customer_name",
+        "type": "string",
+        "max_length": 100,
+        "required": true
+      },
+      {
+        "field": "total_amount",
+        "type": "float",
+        "precision": 12,
+        "scale": 2,
+        "required": true
+      },
+      { "field": "order_date", "type": "datetime", "required": true },
+      { "field": "notes", "type": "string", "max_length": 500 }
+    ],
+    "strict_mode": true
+  }
+}
+```
+
+**Backward Compatibility**: Existing schema files without metadata continue to work unchanged. Metadata validation is optional and can be added incrementally to enhance validation precision.
+
+**Command Options:**
+```bash
+# Basic validation
+vlite schema --conn <connection> --rules <rules_file>
+
+# JSON output for automation
+vlite schema --conn <connection> --rules <rules_file> --output json
+
+# Exit with error code on any failure
+vlite schema --conn <connection> --rules <rules_file> --fail-on-error
+
+# Verbose logging
+vlite schema --conn <connection> --rules <rules_file> --verbose
+```
+
 ---
 
 ## Quick Start: Ad-Hoc Checks with `check`

cli/__init__.py

@@ -5,7 +5,7 @@
 Provides a unified `vlite check` command for data quality checking.
 """
 
-__version__ = "0.4.2"
+__version__ = "0.4.3"
 
 from .app import cli_app
 

cli/app.py

@@ -68,7 +68,7 @@ def _setup_logging() -> None:
 
 
 @click.group(name="vlite", invoke_without_command=True)
-@click.version_option(version="0.4.2", prog_name="vlite")
+@click.version_option(version="0.4.3", prog_name="vlite")
 @click.pass_context
 def cli_app(ctx: click.Context) -> None:
     """