dbset 0.1.0

Thin wrapper on SQLAlchemy with async/await support - simplified database operations

DBset aka AsyncDataset - Thin Wrapper on SQLAlchemy with Async Support

A Python library for simplified database operations, inspired by the original dataset library but with native async/await support and dual sync/async APIs.

Features

• Built on SQLAlchemy 2.x: Thin wrapper providing Pythonic API over SQLAlchemy
• Dual API: Both sync and async interfaces with identical APIs
• Automatic Schema Management: Auto-create tables and columns on insert
• Read-Only Mode: Built-in safety for marketing queries
• Connection Pooling: Efficient connection reuse via SQLAlchemy
• Dict-Based Filtering: Pythonic query API with advanced filters
• Type Inference: Automatic Python → SQLAlchemy type mapping

Installation

pip install dbset                  # base installation
pip install dbset[asyncpg]         # + async PostgreSQL driver
pip install dbset[psycopg2]        # + sync PostgreSQL driver
pip install dbset[postgres]        # + all PostgreSQL drivers
pip install dbset[aiosqlite]       # + async SQLite driver
pip install dbset[all]             # all drivers
pip install dbset[dev]             # development dependencies

Dependencies

• sqlalchemy>=2.0 (core dependency)
• greenlet>=3.0 (for SQLAlchemy async support)
• asyncpg>=0.29.0 (async PostgreSQL driver, optional)
• psycopg2-binary>=2.9.9 (sync PostgreSQL driver, optional)
• aiosqlite>=0.19.0 (async SQLite driver, optional)

Quick Start

Async API (Recommended)

from dbset import async_connect


async def main():
    # Connect to database
    db = await async_connect('postgresql+asyncpg://localhost/mydb')

    # Get table (auto-creates if doesn't exist)
    users = db['users']

    # Insert data
    pk = await users.insert({'name': 'John', 'age': 30})

    # Find with filters
    async for user in users.find(age={'>=': 18}):
        print(user)

    # Update
    await users.update({'age': 31}, name='John')

    # Delete
    await users.delete(name='John')

    # Close connection
    await db.close()

Sync API (For Simple Scripts)

from dbset import connect

# Connect to database
db = connect('postgresql://localhost/mydb')

# Get table
users = db['users']

# Insert data
pk = users.insert({'name': 'John', 'age': 30})

# Find with filters
for user in users.find(age={'>=': 18}):
    print(user)

# Close connection
db.close()

Read-Only Mode (For Safety)

# Marketing queries with read-only safety
db = await async_connect(
    'postgresql+asyncpg://localhost/clinic',
    read_only=True  # Only SELECT allowed
)

patients = db['patients']

# This works - SELECT query
async for patient in patients.find(last_visit={'<': '2024-01-01'}):
    print(patient)

# This raises ReadOnlyError
await patients.insert({'name': 'Hacker'})  # ❌ Blocked!

Advanced Usage

Complex Filters

# Comparison operators
users.find(age={'>=': 18})
users.find(age={'<': 65})
users.find(status={'!=': 'deleted'})

# IN queries
users.find(status={'in': ['active', 'pending', 'approved']})

# LIKE patterns
users.find(email={'like': '[e-mail]'})
users.find(name={'startswith': 'John'})
users.find(name={'endswith': 'son'})

# BETWEEN
users.find(age={'between': [18, 65]})

# NULL checks
users.find(deleted_at={'is': None})

# Multiple conditions (AND)
users.find(age={'>=': 18}, status='active')

Ordering and Pagination

# Order by column (ascending)
async for user in users.find(_order_by='age'):
    print(user)

# Order by column (descending)
async for user in users.find(_order_by='-age'):
    print(user)

# Multiple order columns
async for user in users.find(_order_by=['name', '-age']):
    print(user)

# Pagination
async for user in users.find(_limit=10, _offset=20):
    print(user)

Batch Operations

# Insert many rows
rows = [
    {'name': 'John', 'age': 30},
    {'name': 'Jane', 'age': 25},
    {'name': 'Bob', 'age': 35},
]
count = await users.insert_many(rows)

# Upsert (insert or update)
await users.upsert(
    {'name': 'John', 'age': 31},
    keys=['name']  # Check if name exists
)

Transactions

# Async transactions
async with db.transaction():
    await users.insert({'name': 'Alice'})
    await orders.insert({'user_id': 1, 'total': 100})
    # Both committed together

# Sync transactions
with db.transaction():
    users.insert({'name': 'Alice'})
    orders.insert({'user_id': 1, 'total': 100})

Index Management

AsyncDataset automatically manages indexes for optimal performance.

Automatic Index Creation

When using upsert() or upsert_many() with ensure=True, indexes are automatically created on the key columns:

# Automatic index creation on upsert
await table.upsert(
    {'email': '[e-mail]', 'name': 'Alice', 'age': 30},
    keys=['email'],
    ensure=True  # Auto-creates table, columns, AND index on 'email'
)

# Verify index was created
assert await table.has_index(['email']) is True

# Compound keys create compound indexes
await table.upsert(
    {'email': '[e-mail]', 'country': 'US', 'age': 25},
    keys=['email', 'country'],
    ensure=True  # Auto-creates index on ['email', 'country']
)

# Batch operations create index once before processing
rows = [
    {'email': f'user{i}@example.com', 'name': f'User{i}'}
    for i in range(1000)
]
await table.upsert_many(rows, keys=['email'], ensure=True)
# Index created once, then 1000 fast upserts

# Sync API works identically
table.upsert(
    {'email': '[e-mail]', 'name': 'Charlie'},
    keys=['email'],
    ensure=True
)
assert table.has_index(['email']) is True

Why auto-indexing on upsert?

• Upsert performs lookup (find_one) on every call using the keys parameter
• Without an index, this is a full table scan - O(n) complexity
• With an index, lookups are O(log n) - dramatically faster for large tables
• ensure=True means "set up everything needed for optimal operation"

When indexes are NOT auto-created:

• insert() / insert_many() - no lookup needed, so no critical performance benefit
• upsert() with ensure=False - user has explicit control
• update() methods - updates use existing keys, not critical path

Manual Index Creation

You can always create indexes explicitly for fine-grained control:

# Create single column index
idx_name = await table.create_index('email')
# Returns: 'idx_users_email'

# Create compound index on multiple columns
idx_name = await table.create_index(['country', 'city'])
# Returns: 'idx_users_country_city'

# Create unique index with custom name
idx_name = await table.create_index(
    'username',
    name='unique_username',
    unique=True
)

# Idempotent - creating same index twice succeeds
idx_name = await table.create_index('email')  # First time
idx_name = await table.create_index('email')  # Second time - no error

# Check if index exists
if not await table.has_index('email'):
    await table.create_index('email')

# Check compound index
has_compound = await table.has_index(['country', 'city'])

# Database-specific features (PostgreSQL partial index)
from sqlalchemy import text
idx_name = await table.create_index(
    'email',
    postgresql_where=text("status = 'active'")
)

# Sync API works identically
idx_name = table.create_index('email')
assert table.has_index('email') is True

Index Naming Convention:

• Auto-generated names follow pattern: idx_{table}_{col1}_{col2}
• Long names are truncated to 63 characters (PostgreSQL limit) with hash suffix
• Custom names can be provided via the name parameter

When to Use Indexes:

• Columns frequently used in WHERE clauses
• Columns used in JOIN conditions
• Columns used for sorting (ORDER BY)
• Foreign key columns
• Email/username fields for authentication lookups

Best Practices:

• Create indexes after bulk data imports for better performance
• Use compound indexes for queries filtering on multiple columns together
• Use unique indexes to enforce data integrity constraints
• Monitor index usage - unused indexes slow down writes

Direct SQLAlchemy Access

from sqlalchemy import select, func

# Get SQLAlchemy Table object
users_table = await users.table

# Build complex query with SQLAlchemy
stmt = (
    select(users_table.c.name, func.count().label('count'))
    .where(users_table.c.age > 18)
    .group_by(users_table.c.name)
    .order_by(func.count().desc())
)

# Execute via dataset
async for row in db.query(stmt):
    print(row)

Architecture

Components

dataset/
├── __init__.py           # Public API (connect, async_connect)
├── async_core.py         # AsyncDatabase, AsyncTable (async API)
├── sync_core.py          # Database, Table (sync API)
├── schema.py             # Schema management (DDL operations)
├── query.py              # FilterBuilder (dict → SQLAlchemy WHERE)
├── types.py              # TypeInference (Python → SQLAlchemy types)
├── validators.py         # ReadOnlyValidator (SQL safety)
├── connection.py         # Connection pooling
└── exceptions.py         # Exception hierarchy

How It Works

1. Schema Discovery: Reflects database schema using SQLAlchemy MetaData
2. Auto-Create: Automatically creates tables/columns on insert
3. Type Inference: Infers SQLAlchemy types from Python values
4. Query Building: Translates dict filters to SQLAlchemy WHERE clauses
5. Validation: Checks SQL safety in read-only mode
6. Execution: Executes via SQLAlchemy async/sync engines

SQLAlchemy Integration

AsyncDataset is a thin wrapper on SQLAlchemy:

# Dataset simplified API
await table.insert({'name': 'John', 'age': 30})

# Translates to SQLAlchemy under the hood
from sqlalchemy import insert
stmt = insert(table._table).values(name='John', age=30)
await conn.execute(stmt)

You always have direct SQLAlchemy access:

• table.table → SQLAlchemy Table object
• db.query(sqlalchemy_statement) → Execute SQLAlchemy statements
• db.engine → SQLAlchemy Engine
• db.metadata → SQLAlchemy MetaData

Testing

# Run all tests
uv run pytest tests/unit/dataset/ -v

# Run specific test file
uv run pytest tests/unit/dataset/test_async_core.py -v

# With coverage
uv run pytest tests/unit/dataset/ --cov=src/dataset --cov-report=html

Marketing Churn Query

from dbset import async_connect
from datetime import datetime, timedelta


async def find_churn_customers(db_url: str):
    """Find patients who haven't visited in 6+ months."""
    db = await async_connect(db_url, read_only=True)

    six_months_ago = datetime.now() - timedelta(days=180)
    patients = db['patients']

    churn_list = []
    async for patient in patients.find(
            last_visit={'<': six_months_ago},
            status='active',
            _limit=100,
            _order_by='-last_visit'
    ):
        churn_list.append(patient)

    await db.close()
    return churn_list

CSV Import with Auto-Schema

from dbset import connect
import csv


def import_customers(csv_path: str):
    """Import CSV with automatic table creation."""
    db = connect('postgresql://localhost/clinic')
    customers = db['customers']

    with open(csv_path) as f:
        reader = csv.DictReader(f)
        rows = list(reader)

    # Auto-creates table with columns from CSV headers
    count = customers.insert_many(rows, ensure=True)

    print(f"Imported {count} rows")
    db.close()

Status

Phase 1-3 Complete:

• ✅ Infrastructure (exceptions, types, validators, connection, query)
• ✅ Schema management (DDL operations)
• ✅ Async API (AsyncDatabase, AsyncTable)
• ✅ Sync API (Database, Table)
• ✅ Unit tests (63 tests passing)

Remaining Phases:

• Integration tests with PostgreSQL
• Performance benchmarks
• Documentation and examples

Design Philosophy

AsyncDataset = Simplified API + SQLAlchemy Power

• Use dataset's simple API for common operations (80% use case)
• Use SQLAlchemy directly for complex queries (20% use case)
• No magic - everything translates to standard SQLAlchemy code
• Always possible to drop down to SQLAlchemy when needed

License

Apache-2.0