pgconnect 0.6.5

A PostgreSQL connection and ORM library

PgConnect

PgConnect is a PostgreSQL connection and ORM library for Python. It provides an easy-to-use interface for connecting to PostgreSQL databases and performing common database operations.

Features

• Easy connection to PostgreSQL databases
• ORM-like interface for defining and interacting with database tables
• Support for various PostgreSQL data types
• Advanced caching mechanism with Redis support for improved performance
• RecordLike objects that behave exactly like asyncpg.Record for cached data
• Connection pooling for high-performance applications
• Comprehensive filtering and search capabilities

Installation

You can install PgConnect using pip:

pip install pgconnect

Requirements

• Python 3.6+
• asyncpg
• cachetools
• redis (for Redis caching support)

Caching

PgConnect supports two types of caching to improve performance by reducing database queries:

1. In-Memory Caching (TTLCache): Fast, local caching using Python's memory
2. Redis Caching: Distributed caching with Redis for scalable applications

Caching Types

In-Memory Caching

users = pgconnect.Table(
    name="users",
    connection=connection,
    columns=columns,
    cache=True,              # Enable in-memory caching
    cache_key="id",          # Cache key for lookups
    cache_ttl=300,           # TTL in seconds (5 minutes)
    cache_maxsize=1000       # Maximum cache entries
)

Redis Caching

# Set up Redis connection
redis_connection = pgconnect.RedisConnection(
    host='localhost',
    port=6379,
    password='your_password',
    decode_responses=True
)

users = pgconnect.Table(
    name="users",
    connection=connection,
    columns=columns,
    redis_cache=True,              # Enable Redis caching
    redis_connection=redis_connection,
    cache_key="id",                # Cache key for lookups
    cache_ttl=300                  # TTL in seconds (5 minutes)
)

RecordLike Objects

Cached database records are returned as RecordLike objects that behave exactly like asyncpg.Record:

# Insert and cache a user
user = await users.insert(name="John", email="[e-mail]")

# Get from cache - returns RecordLike object
cached_user = await users.getCache("user_1")

# Access data like asyncpg.Record
print(cached_user.name)           # Attribute access
print(cached_user['email'])       # Dictionary access
print(cached_user.get('age', 0))  # get() method with default
print(len(cached_user))           # Length
print('name' in cached_user)      # Membership test

# Iterate over values
for value in cached_user:
    print(value)

# Get keys, values, items
for key in cached_user.keys():
    print(key)

Benefits of Caching

1. Reduced Latency: Queries served directly from cache (microseconds vs milliseconds)
2. Lower Database Load: Fewer queries sent to PostgreSQL server
3. Improved Scalability: Handle more concurrent requests efficiently
4. Distributed Caching: Redis support for multi-instance applications
5. Record Compatibility: Cached objects behave exactly like original asyncpg.Record objects

When to Use Caching

• In-Memory Caching: Single-instance applications, fast local access
• Redis Caching: Multi-instance applications, shared cache across services
• For frequently read data that doesn't change often
• To optimize expensive database queries and improve response times

Advanced Caching Example

Here’s an example showing how caching can improve performance:

# Enable caching for the table with a cache key
users = pgconnect.Table(
    name="users",
    connection=connection,
    columns=[
        pgconnect.Column(name="id", type=pgconnect.DataType.SERIAL().primary_key().not_null()),
        pgconnect.Column(name="email", type=pgconnect.DataType.VARCHAR().unique().not_null()),
        pgconnect.Column(name="username", type=pgconnect.DataType.VARCHAR()),
        pgconnect.Column(name="password", type=pgconnect.DataType.TEXT()),
        pgconnect.Column(name="created_at", type=pgconnect.DataType.TIMESTAMP().default("NOW()")),
    ],
    cache=True,  # Enable caching
    cache_key="id",  # Specify cache key for lookups
    cache_ttl=60  # Cache TTL in seconds (optional, default is no expiry)
    cache_maxsize=1000  # Maximum number of items in the cache (optional, default is 1000)
)

# First query - data fetched from the database and stored in cache
user = await users.select("id", "username", email="[e-mail]")
print("Fetched from database:", user)

# Subsequent query with the same parameters - data fetched from cache
cached_user = await users.select("id", "username", email="[e-mail]")
print("Fetched from cache:", cached_user)

Performance Comparison:

• Without Caching: Each query triggers a request to the PostgreSQL server, which involves network overhead and database processing time.
• With Caching: After the first query, subsequent requests with the same parameters are served from the cache, reducing query time from milliseconds to microseconds.

Performance Comparison:

• Without Caching: Each query = PostgreSQL network request (5-50ms)
• With In-Memory Caching: Cached queries served in microseconds
• With Redis Caching: Distributed cache across multiple instances

By using caching strategically in your application, you can significantly improve response times and reduce database workload.

Usage

Connecting to the Database

import pgconnect
import asyncio

async def main():
    connection = pgconnect.Connection(
        host="your_host",
        port=5432,
        user="your_user",
        password="your_password",
        database="your_database"
    )

    # Define your table schema
    users = pgconnect.Table(
        name="users",
        connection=connection,
        columns=[
            pgconnect.Column(
                name="id",
                type=pgconnect.DataType.SERIAL().primary_key().not_null()
            ),
            pgconnect.Column(
                name="email",
                type=pgconnect.DataType.VARCHAR().unique().not_null()
            ),
            pgconnect.Column(
                name="username",
                type=pgconnect.DataType.VARCHAR()
            ),
            pgconnect.Column(
                name="password",
                type=pgconnect.DataType.TEXT(),
            ),
            pgconnect.Column(
                name="created_at",
                type=pgconnect.DataType.TIMESTAMP().default("NOW()")
            )
        ],
        cache=True,         # Enable in-memory caching
        cache_key="id"      # Cache by ID field
    )

    await users.create()
    print(users)

if __name__ == "__main__":
    asyncio.run(main())

Note: The above example uses in-memory caching. For Redis caching, replace cache=True with redis_cache=True and add a redis_connection parameter.

Inserting Data

await users.insert(
    email="[e-mail]",
    username="example",
    password="password"
)

Here, this is inserting a new row into the users table with the email as [e-mail], username as example, and password as password.

Selecting Data

user = await users.select("id", "username", email="[e-mail]")
print(user)

Here, this is selecting the id and username columns for the row where the email is [e-mail].

Updating Data

await users.update({"id": 1}, username="new_username")

Here, this is updating the username column to new_username for the row where the id is 1.

Deleting Data

await users.delete(id=1)

Here, this is deleting the row from the users table where the id is 1.

Cache Operations

# Set cache value
await users.setCache("user_123", user_data)

# Get cache value (returns RecordLike object for records)
cached_user = await users.getCache("user_123")

# Check if cache key exists
exists = await users.cacheExists("user_123")

# Clear Redis cache for table
await users.clear_redis_cache()

# Ping Redis connection
ping_time = await users.pingRedis()
print(f"Redis ping: {ping_time}ms")

Counting Rows

user_count = await users.count()
print(user_count)

Here, this is counting the total number of rows in the users table.

Checking Existence

user_exists = await users.exists(id=1)
print(user_exists)

Here, this is checking if there is any row in the users table where the id is 1.

Getting Columns

columns = await users.get_columns()
print(columns)

Here, this is retrieving the names and data types of all columns in the users table.

Dropping the Table

await users.drop()

Here, this is dropping the users table from the PostgreSQL database.

Truncating the Table

await users.truncate()

Here, this is truncating the users table, which removes all rows from the table.

Example Usage in a Script

Here is a complete example script demonstrating how to use these methods:

import pgconnect
import asyncio

async def main():
    connection = pgconnect.Connection(
        host="your_host",
        port=5432,
        user="your_user",
        password="your_password",
        database="your_database"
    )

    users = pgconnect.Table(
        name="users",
        connection=connection,
        columns=[
            pgconnect.Column(
                name="id",
                type=pgconnect.DataType.SERIAL().primary_key().not_null()
            ),
            pgconnect.Column(
                name="email",
                type=pgconnect.DataType.VARCHAR().unique().not_null()
            ),
            pgconnect.Column(
                name="username",
                type=pgconnect.DataType.VARCHAR()
            ),
            pgconnect.Column(
                name="password",
                type=pgconnect.DataType.TEXT(),
            ),
            pgconnect.Column(
                name="created_at",
                type=pgconnect.DataType.TIMESTAMP().default("NOW()")
            )
        ],
        cache=True,
        cache_key="id",
    )

    await users.create()
    print("Table created")

    # Insert data
    await users.insert(
        email="[e-mail]",
        username="example",
        password="password"
    )
    print("Data inserted")

    # Select data
    user = await users.select("id", "username", email="[e-mail]")
    print("Selected user:", user)

    # Update data
    await users.update({"id": 1}, username="new_username")
    print("Data updated")

    # Delete data
    await users.delete(id=1)
    print("Data deleted")

    # Count rows
    user_count = await users.count()
    print("User count:", user_count)

    # Check existence
    user_exists = await users.exists(id=1)
    print("User exists:", user_exists)

    # Get columns
    columns = await users.get_columns()
    print("Table columns:", columns)

    # Drop table
    await users.drop()
    print("Table dropped")

    # Truncate table
    await users.truncate()
    print("Table truncated")

if __name__ == "__main__":
    asyncio.run(main())

This script demonstrates how to use the Table class to perform various database operations, including creating a table, inserting, updating, deleting, selecting data, counting rows, checking existence, getting columns, dropping the table, and truncating the table.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Author

AdnanBinPulok - GitHub