SQLGlot Vertica Dialect

A comprehensive Vertica dialect implementation for SQLGlot, a Python SQL parser and transpiler.

Features

This Vertica dialect provides full-featured support for Vertica SQL syntax, including:

Core Functionality

• Complete SQL parsing and generation
• Vertica-specific data types (TIMESTAMPTZ, BINARY, etc.)
• Identifier quoting with double quotes
• Heredoc string support

Date and Time Functions

• DATEADD(unit, interval, timestamp) - Add intervals to dates/timestamps
• DATEDIFF(unit, start_date, end_date) - Calculate date differences
• DATE_TRUNC(unit, timestamp) - Truncate timestamps to specified unit
• TO_CHAR(timestamp, format) - Format timestamps as strings
• TO_DATE(string, format) - Parse strings as dates
• TO_TIMESTAMP(string, format) - Parse strings as timestamps
• CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, NOW()

String Functions

• ILIKE / NOT ILIKE - Case-insensitive pattern matching
• LIKE / NOT LIKE - Case-sensitive pattern matching
• SUBSTRING(string, start, length) - Extract substrings
• TRIM() - Remove whitespace
• Standard string functions (LENGTH, UPPER, LOWER, etc.)

Mathematical Functions

• RANDOM() - Generate random numbers
• Standard math functions (ABS, CEIL, FLOOR, ROUND, SQRT, POWER)

Hash Functions

• MD5(string) - MD5 hash
• SHA1(string) - SHA1 hash

Array Support

• ARRAY[...] syntax for array literals
• Array operations and functions

Window Functions

• Complete support for window functions
• ROW_NUMBER(), RANK(), LAG(), LEAD(), etc.
• OVER clauses with PARTITION BY and ORDER BY

Advanced Features

• Common Table Expressions (CTEs)
• Subqueries and EXISTS clauses
• All JOIN types (INNER, LEFT, RIGHT, FULL OUTER, CROSS)
• Aggregate functions with GROUP BY and HAVING
• CASE WHEN expressions
• Complex data types and constraints

Installation

pip install vertica-sqlglot-dialect

For development:

pip install vertica-sqlglot-dialect[dev]

Usage

Basic Usage

from sqlglot import transpile, parse_one

# Parse and generate Vertica SQL
sql = "SELECT DATEADD(DAY, 1, CURRENT_DATE)"
parsed = parse_one(sql, read="vertica")
generated = parsed.sql(dialect="vertica")
print(generated)  # SELECT DATEADD(DAY, 1, CURRENT_DATE)

# Transpile from other dialects to Vertica
postgres_sql = "SELECT NOW()"
vertica_sql = transpile(postgres_sql, read='postgres', write='vertica')[0]
print(vertica_sql)  # SELECT CURRENT_TIMESTAMP

Advanced Examples

# Complex query with CTEs and window functions
complex_query = """
WITH sales_data AS (
    SELECT 
        region,
        DATE_TRUNC(MONTH, sale_date) AS month,
        SUM(amount) AS total_sales,
        ROW_NUMBER() OVER (PARTITION BY region ORDER BY SUM(amount) DESC) AS rank
    FROM sales
    WHERE sale_date >= CURRENT_DATE - INTERVAL '1' YEAR
    GROUP BY region, DATE_TRUNC(MONTH, sale_date)
)
SELECT 
    region,
    month,
    total_sales,
    CASE 
        WHEN rank = 1 THEN 'Top Month'
        ELSE 'Other'
    END AS category
FROM sales_data
WHERE rank <= 5
ORDER BY region, total_sales DESC
"""

parsed = parse_one(complex_query, read="vertica")
print(parsed.sql("vertica", pretty=True))

Vertica-Specific Features

# Date functions
sql = "SELECT DATEDIFF(DAY, '2023-01-01', '2023-12-31')"
result = parse_one(sql, read="vertica").sql("vertica")

# Array operations
sql = "SELECT ARRAY[1, 2, 3, 4, 5]"
result = parse_one(sql, read="vertica").sql("vertica")

# Case-insensitive matching
sql = "SELECT * FROM users WHERE name ILIKE '%john%'"
result = parse_one(sql, read="vertica").sql("vertica")

# Timestamp with timezone
sql = "CREATE TABLE events (id INTEGER, created_at TIMESTAMPTZ)"
result = parse_one(sql, read="vertica").sql("vertica")

Development

Setup Development Environment

git clone https://github.com/luisdelatorre/vertica-sqlglot-dialect.git
cd vertica-sqlglot-dialect
python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate
pip install -e .[dev]

Running Tests

# Run all tests
pytest

# Run with coverage
pytest --cov=vertica_sqlglot_dialect

# Run specific test file
pytest tests/test_vertica.py

# Run specific test method
pytest tests/test_vertica.py::TestVertica::test_vertica_date_functions

Code Quality

# Format code
black vertica_sqlglot_dialect tests

# Sort imports
isort vertica_sqlglot_dialect tests

# Type checking
mypy vertica_sqlglot_dialect

Testing

The dialect includes comprehensive tests covering:

• Basic SQL operations (SELECT, INSERT, UPDATE, DELETE)
• All supported data types
• Date and time functions
• String and mathematical functions
• Window functions and aggregations
• JOIN operations
• Subqueries and CTEs
• Complex query patterns
• Transpilation from other dialects
• Edge cases and error conditions

The test suite follows the same patterns as other SQLGlot dialect tests, ensuring consistency and reliability.

Compatibility

• Python: 3.8+
• SQLGlot: 26.0.0+
• Vertica: Compatible with Vertica SQL syntax

Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Add tests for new functionality
4. Ensure all tests pass
5. Submit a pull request

License

MIT License - see LICENSE file for details.

📁 Examples

This package includes comprehensive examples demonstrating various use cases. See the examples/ directory for detailed demonstrations.

🚀 Quick Start Examples

# Run basic usage examples
python examples/basic_usage.py

# Run advanced transformation examples  
python examples/advanced_transformations.py

# Run data migration examples
python examples/data_migration.py

# Run performance analysis examples
python examples/performance_analysis.py

# Run comprehensive demonstration
python examples/run_all_examples.py

📋 Example Categories

1. examples/basic_usage.py - Fundamental operations

   • Basic SQL parsing with Vertica syntax
   • Cross-dialect transpilation
   • AST inspection and manipulation
   • Error handling for unsupported features

2. examples/advanced_transformations.py - AST manipulation

   • Custom query transformations
   • Query optimization using SQLGlot
   • Schema analysis and lineage tracking
   • Advanced AST rewriting patterns

3. examples/data_migration.py - Database migration

   • DDL conversion between databases
   • Function migration (date/time, string, hash)
   • Data type mapping
   • Batch script processing and validation

4. examples/performance_analysis.py - Query optimization

   • Query complexity analysis
   • Anti-pattern detection
   • Index recommendation
   • Performance benchmarking

Common Use Cases

# Database Migration
from sqlglot import transpile
from sqlglot_vertica.vertica import Vertica

vertica_sql = "SELECT DATEDIFF('day', hire_date, CURRENT_DATE) FROM employees"
postgres_sql = transpile(vertica_sql, read=Vertica, write="postgres")[0]

# Query Analysis  
from sqlglot import parse_one
ast = parse_one("SELECT MD5(email) FROM users WHERE active = true", read=Vertica)
tables = [table.name for table in ast.find_all(exp.Table)]
functions = [func.sql() for func in ast.find_all(exp.Func)]

# Error Handling
from sqlglot.errors import ParseError, UnsupportedError
try:
    parse_one("SELECT $$invalid syntax$$", read=Vertica)
except ParseError as e:
    print(f"Parse error: {e}")

Acknowledgments

• Built on top of the excellent SQLGlot library
• Inspired by existing SQLGlot dialect implementations, particularly Postgres
• Designed to be compatible with Vertica SQL syntax and semantics