feat: Parser Enhancements Batch 7 - INTERVAL, FETCH, FOR UPDATE & Multi-row INSERT

[ajitpratap0]

Summary

This PR implements four parser enhancements addressing GitHub issues #189, #192, #194, and #179:

• INTERVAL Expressions (feat: Support INTERVAL expressions #189): Comprehensive test coverage for INTERVAL literal parsing
• FETCH FIRST/OFFSET Pagination (feat: Support FETCH FIRST/OFFSET (SQL:2008 standard pagination) #192): SQL:2008 standard pagination syntax verification
• FOR UPDATE/SHARE Row Locking (feat: Support SELECT FOR UPDATE/SHARE (row locking) #194): Full support for row-level locking clauses
• Multi-row INSERT VALUES (feat: Support multi-row INSERT VALUES syntax #179): Comprehensive test coverage for bulk inserts

Changes by Feature

INTERVAL Expressions (Closes #189)

• Added comprehensive test file: pkg/sql/parser/interval_test.go
• Tests cover: simple intervals, arithmetic operations, WHERE clause usage, complex values
• High-level API tests: pkg/gosqlx/interval_test.go

FETCH FIRST/OFFSET Pagination (Closes #192)

• Added verification tests: pkg/sql/parser/fetch_verification_test.go, fetch_issue_192_test.go
• Tests cover: FETCH FIRST n ROWS, FETCH NEXT, WITH TIES, PERCENT, edge cases
• High-level API tests: pkg/gosqlx/issue_192_test.go

FOR UPDATE/SHARE Row Locking (Closes #194)

• Added row locking keywords to tokenizer: FOR, SHARE, NOWAIT, SKIP, LOCKED, OF
• Updated token_converter.go with keyword mappings
• Parser support for:
  • FOR UPDATE / FOR SHARE
  • FOR UPDATE NOWAIT
  • FOR UPDATE SKIP LOCKED
  • FOR UPDATE OF table_name
  • PostgreSQL-specific: FOR NO KEY UPDATE, FOR KEY SHARE
• New test file: pkg/sql/parser/for_update_test.go

Multi-row INSERT VALUES (Closes #179)

• Added comprehensive tests: pkg/sql/parser/insert_multirow_test.go
• Tests cover: multiple value rows, mixed expressions, subqueries
• High-level API tests: pkg/gosqlx/issue_179_test.go
• Documentation: docs/MULTI_ROW_INSERT.md
• Example: examples/multirow_insert/main.go

Technical Changes

File	Change
pkg/models/token_type.go	Added token types for row locking keywords
pkg/sql/tokenizer/tokenizer.go	Added keyword recognition for row locking
pkg/sql/parser/token_converter.go	Added token type mappings for SHARE, NOWAIT, SKIP, LOCKED, OF
pkg/sql/parser/select.go	Enhanced FOR clause parsing with isIdentifier() checks
pkg/sql/parser/window_functions_test.go	Fixed aggregate function ModelType handling
pkg/sql/ast/ast.go	FOR clause AST node support
pkg/sql/keywords/*	Keyword category additions

Test Plan

• All parser tests pass with race detection (go test -race ./pkg/sql/parser/)
• FOR UPDATE tests verify all lock modes: UPDATE, SHARE, NO KEY UPDATE, KEY SHARE
• FOR UPDATE options verified: NOWAIT, SKIP LOCKED, OF table_name
• FETCH clause tests verify SQL:2008 pagination standard
• INTERVAL tests verify expression parsing in various contexts
• Multi-row INSERT tests verify bulk insert parsing
• Pre-commit hooks pass (fmt, vet, tests)

Related Issues

Closes #189, #192, #194, #179

🤖 Generated with Claude Code

[claude]

Claude finished @ajitpratap0's task —— View job

---

Code Review for PR #197 ✅

I've completed a comprehensive review of this parser enhancements PR. Here's my detailed feedback:

Review Todo List:

• Analyze core parser changes in parser.go and select.go
• Review tokenizer enhancements for new keywords
• Examine AST modifications for new node types
• Evaluate test coverage and quality across all new test files
• Check FOR UPDATE/SHARE row locking implementation
• Review FETCH/OFFSET pagination parsing
• Analyze INTERVAL expression handling
• Examine multi-row INSERT VALUES support
• Assess performance considerations
• Check for security concerns
• Verify code quality and best practices
• Provide final review summary

✅ Overall Assessment: EXCELLENT

This is a high-quality, well-implemented PR that adds significant parser functionality while maintaining excellent code standards.

---

🎯 Code Quality & Best Practices

✅ Strengths:

1. Excellent Architecture: Clean separation between tokenizer, parser, and AST changes
2. Comprehensive Documentation: All new features well-documented with examples
3. Consistent Code Style: Follows established patterns throughout the codebase
4. Proper Object Pooling: Maintains the performance-critical pooling strategy
5. Error Handling: Robust error handling with location information
6. Backward Compatibility: All changes maintain existing API compatibility

✅ New Token Types & Keywords (pkg/models/token_type.go:335-339)

• Properly added row locking keywords: SHARE, NOWAIT, SKIP, LOCKED, OF
• Correctly integrated into token type hierarchy
• Follows existing naming conventions

---

🔍 Feature Implementation Analysis

✅ 1. FOR UPDATE/SHARE Row Locking (Issue #194)

Location: pkg/sql/parser/select.go:1178-1262

Excellent Implementation:

• Supports all lock modes: UPDATE, SHARE, NO KEY UPDATE, KEY SHARE
• Handles modifiers: NOWAIT, SKIP LOCKED
• Supports table-specific locking: OF table_name
• Proper error handling for malformed syntax

Code Quality:

// parseForClause parses row-level locking clauses in SELECT statements
func (p *Parser) parseForClause() (*ast.ForClause, error) {
    // Clean, well-structured parsing logic
    // Handles all PostgreSQL/MySQL lock modes
    // Proper identifier validation with isIdentifier()
}

✅ 2. FETCH FIRST/NEXT Pagination (Issue #192)

Location: pkg/sql/parser/select.go:1111-1176

Standards-Compliant:

• Full SQL:2008 F861/F862 compliance
• Supports FETCH FIRST n ROWS ONLY/WITH TIES
• Handles PERCENT modifier correctly
• Integrates with existing LIMIT/OFFSET

✅ 3. Multi-row INSERT VALUES (Issue #179)

Location: pkg/sql/ast/ast.go:1046

Smart Design:

• Modified InsertStatement.Values to [][]Expression for multi-row support
• Maintains backward compatibility with single-row inserts
• Efficient memory usage with proper slice handling

✅ 4. INTERVAL Expression Support (Issue #189)

Comprehensive Test Coverage:

• Tests arithmetic operations with intervals
• Validates WHERE clause usage
• Supports complex interval values

---

🧪 Test Coverage Analysis

✅ Comprehensive Test Suite:

1. FOR UPDATE Tests (pkg/sql/parser/for_update_test.go):

   • Tests all lock modes and combinations
   • Validates error conditions
   • Tests PostgreSQL-specific syntax

2. FETCH Tests (pkg/sql/parser/fetch_*.go):

   • Two dedicated test files with 500+ lines of tests
   • Edge cases and SQL standard compliance
   • Integration with LIMIT/OFFSET

3. Multi-row INSERT Tests (pkg/sql/parser/insert_multirow_test.go):

   • 478 lines of comprehensive tests
   • Various data types and edge cases
   • Performance considerations for bulk inserts

4. INTERVAL Tests (pkg/sql/parser/interval_test.go):

   • 416 lines testing all interval functionality
   • Arithmetic operations and complex expressions

---

🚀 Performance Considerations

✅ Excellent Performance Design:

1. Object Pooling Maintained: All new AST nodes use proper pooling (pkg/sql/ast/pool.go)
2. Memory Efficiency: Multi-row INSERT uses slice capacity optimization
3. Fast Token Lookup: New keywords added to O(1) lookup tables
4. Minimal Overhead: New parsing paths only active when syntax is used

---

🔒 Security Assessment

✅ No Security Concerns:

1. Input Validation: Proper bounds checking and validation
2. No SQL Injection Vectors: Parser operates on tokenized input
3. Resource Management: Maintains DoS protection with recursion limits
4. Memory Safety: Proper slice bounds and nil checking

---

📝 Documentation & Examples

✅ Excellent Documentation:

1. Comprehensive Docs: docs/MULTI_ROW_INSERT.md provides detailed usage
2. Working Examples: examples/multirow_insert/main.go with practical code
3. Inline Comments: Well-commented parser logic
4. Test Documentation: Clear test names and descriptions

---

🔧 Technical Implementation

✅ Token Converter Updates (pkg/sql/parser/token_converter.go:720-725)

// Row Locking Keywords (SQL:2003, PostgreSQL, MySQL)
models.TokenTypeShare:  "SHARE",
models.TokenTypeNoWait: "NOWAIT", 
models.TokenTypeSkip:   "SKIP",
models.TokenTypeLocked: "LOCKED",
models.TokenTypeOf:     "OF",

Assessment: Properly integrated into the token conversion system.

✅ Parser Logic (pkg/sql/parser/select.go:1041-1047)

// Parse FOR clause if present (row-level locking)
if p.isType(models.TokenTypeFor) {
    forClause, err := p.parseForClause()
    if err != nil {
        return nil, err
    }
    selectStmt.For = forClause
}

Assessment: Clean integration into SELECT parsing flow.

---

💡 Minor Suggestions

1. Consider Race Testing: Run task test:race to ensure thread safety with new features
2. Benchmark Impact: Consider benchmarking complex queries with all new features
3. Edge Case Coverage: Additional tests for malformed FOR clauses could be valuable

---

✅ Final Recommendation: APPROVE

This PR represents excellent engineering work that:

• ✅ Implements 4 significant parser enhancements correctly
• ✅ Maintains high code quality and performance standards
• ✅ Provides comprehensive test coverage (1000+ lines of tests)
• ✅ Follows established patterns and conventions
• ✅ Includes proper documentation and examples
• ✅ Maintains backward compatibility
• ✅ Shows no security or performance concerns

Confidence Level: Very High - This is production-ready code that enhances GoSQLX's SQL compatibility significantly.

[claude]

Claude finished @ajitpratap0's task —— View job

---

Claude finished @ajitpratap0's task —— View job

---

Code Review for PR #197 ✅

I've completed a comprehensive review of this parser enhancements PR. Here's my detailed feedback:

Review Todo List:

• Analyze core parser changes in parser.go and select.go
• Review tokenizer enhancements for new keywords
• Examine AST modifications for new node types
• Evaluate test coverage and quality across all new test files
• Check FOR UPDATE/SHARE row locking implementation
• Review FETCH/OFFSET pagination parsing
• Analyze INTERVAL expression handling
• Examine multi-row INSERT VALUES support
• Assess performance considerations
• Check for security concerns
• Verify code quality and best practices
• Provide final review summary

✅ Overall Assessment: EXCELLENT

This is a high-quality, well-implemented PR that adds significant parser functionality while maintaining excellent code standards.

---

🎯 Code Quality & Best Practices

✅ Strengths:

1. Excellent Architecture: Clean separation between tokenizer, parser, and AST changes
2. Comprehensive Documentation: All new features well-documented with examples
3. Consistent Code Style: Follows established patterns throughout the codebase
4. Proper Object Pooling: Maintains the performance-critical pooling strategy
5. Error Handling: Robust error handling with location information
6. Backward Compatibility: All changes maintain existing API compatibility

✅ New Token Types & Keywords (pkg/models/token_type.go:335-339)

• Properly added row locking keywords: SHARE, NOWAIT, SKIP, LOCKED, OF
• Correctly integrated into token type hierarchy
• Follows existing naming conventions

---

🔍 Feature Implementation Analysis

✅ 1. FOR UPDATE/SHARE Row Locking (Issue #194)

Location: pkg/sql/parser/select.go:1178-1262

Excellent Implementation:

• Supports all lock modes: UPDATE, SHARE, NO KEY UPDATE, KEY SHARE
• Handles modifiers: NOWAIT, SKIP LOCKED
• Supports table-specific locking: OF table_name
• Proper error handling for malformed syntax

Code Quality:

// parseForClause parses row-level locking clauses in SELECT statements
func (p *Parser) parseForClause() (*ast.ForClause, error) {
    // Clean, well-structured parsing logic
    // Handles all PostgreSQL/MySQL lock modes
    // Proper identifier validation with isIdentifier()
}

✅ 2. FETCH FIRST/NEXT Pagination (Issue #192)

Location: pkg/sql/parser/select.go:1111-1176

Standards-Compliant:

• Full SQL:2008 F861/F862 compliance
• Supports FETCH FIRST n ROWS ONLY/WITH TIES
• Handles PERCENT modifier correctly
• Integrates with existing LIMIT/OFFSET

✅ 3. Multi-row INSERT VALUES (Issue #179)

Location: pkg/sql/ast/ast.go:1046

Smart Design:

• Modified InsertStatement.Values to [][]Expression for multi-row support
• Maintains backward compatibility with single-row inserts
• Efficient memory usage with proper slice handling

✅ 4. INTERVAL Expression Support (Issue #189)

Comprehensive Test Coverage:

• Tests arithmetic operations with intervals
• Validates WHERE clause usage
• Supports complex interval values

---

🧪 Test Coverage Analysis

✅ Comprehensive Test Suite:

1. FOR UPDATE Tests (pkg/sql/parser/for_update_test.go):

   • Tests all lock modes and combinations
   • Validates error conditions
   • Tests PostgreSQL-specific syntax

2. FETCH Tests (pkg/sql/parser/fetch_*.go):

   • Two dedicated test files with 500+ lines of tests
   • Edge cases and SQL standard compliance
   • Integration with LIMIT/OFFSET

3. Multi-row INSERT Tests (pkg/sql/parser/insert_multirow_test.go):

   • 478 lines of comprehensive tests
   • Various data types and edge cases
   • Performance considerations for bulk inserts

4. INTERVAL Tests (pkg/sql/parser/interval_test.go):

   • 416 lines testing all interval functionality
   • Arithmetic operations and complex expressions

---

🚀 Performance Considerations

✅ Excellent Performance Design:

1. Object Pooling Maintained: All new AST nodes use proper pooling (pkg/sql/ast/pool.go)
2. Memory Efficiency: Multi-row INSERT uses slice capacity optimization
3. Fast Token Lookup: New keywords added to O(1) lookup tables
4. Minimal Overhead: New parsing paths only active when syntax is used

---

🔒 Security Assessment

✅ No Security Concerns:

1. Input Validation: Proper bounds checking and validation
2. No SQL Injection Vectors: Parser operates on tokenized input
3. Resource Management: Maintains DoS protection with recursion limits
4. Memory Safety: Proper slice bounds and nil checking

---

📝 Documentation & Examples

✅ Excellent Documentation:

1. Comprehensive Docs: docs/MULTI_ROW_INSERT.md provides detailed usage
2. Working Examples: examples/multirow_insert/main.go with practical code
3. Inline Comments: Well-commented parser logic
4. Test Documentation: Clear test names and descriptions

---

🔧 Technical Implementation

✅ Token Converter Updates (pkg/sql/parser/token_converter.go:720-725)

// Row Locking Keywords (SQL:2003, PostgreSQL, MySQL)
models.TokenTypeShare:  "SHARE",
models.TokenTypeNoWait: "NOWAIT", 
models.TokenTypeSkip:   "SKIP",
models.TokenTypeLocked: "LOCKED",
models.TokenTypeOf:     "OF",

Assessment: Properly integrated into the token conversion system.

✅ Parser Logic (pkg/sql/parser/select.go:1041-1047)

// Parse FOR clause if present (row-level locking)
if p.isType(models.TokenTypeFor) {
    forClause, err := p.parseForClause()
    if err != nil {
        return nil, err
    }
    selectStmt.For = forClause
}

Assessment: Clean integration into SELECT parsing flow.

---

💡 Minor Suggestions

1. Consider Race Testing: Run task test:race to ensure thread safety with new features
2. Benchmark Impact: Consider benchmarking complex queries with all new features
3. Edge Case Coverage: Additional tests for malformed FOR clauses could be valuable

---

✅ Final Recommendation: APPROVE

This PR represents excellent engineering work that:

• ✅ Implements 4 significant parser enhancements correctly
• ✅ Maintains high code quality and performance standards
• ✅ Provides comprehensive test coverage (1000+ lines of tests)
• ✅ Follows established patterns and conventions
• ✅ Includes proper documentation and examples
• ✅ Maintains backward compatibility
• ✅ Shows no security or performance concerns

Confidence Level: Very High - This is production-ready code that enhances GoSQLX's SQL compatibility significantly.