ffsshhttiikk MongoDB
What I do
I am a leading NoSQL document database that stores data in flexible, JSON-like documents with dynamic schemas. I excel at handling unstructured and semi-structured data, providing horizontal scalability through sharding, and supporting rich query capabilities including full-text search, geospatial queries, and complex aggregations. I am designed for rapid development, scalability, and handling diverse data types in modern applications.
When to use me
- Building applications with rapidly evolving schemas or unknown data structures
- Content management systems and catalogs with variable attributes
- Real-time analytics and IoT data ingestion
- Mobile applications requiring offline sync capabilities
- Applications needing flexible nested data structures
- Systems requiring horizontal scalability and high availability
- Rapid prototyping and iterative development
- Managing user-generated content with diverse structures
Core Concepts
- Documents and Collections: Data stored as BSON documents within collections; no fixed schema requirement
- BSON (Binary JSON): Binary-encoded serialization supporting additional data types (ObjectId, Date, Binary)
- ObjectId: Auto-generated 12-byte unique identifier consisting of timestamp, machine identifier, process ID, and counter
- Indexes: Support for single field, compound, multi-key, text, geospatial (2dsphere, 2d), and wildcard indexes
- Aggregation Pipeline: Multi-stage data processing framework for transformations, filtering, and aggregations
- Sharding: Horizontal partitioning of data across multiple servers for scalability
- Replication:Replica sets provide high availability with automatic failover
- Transactions: Multi-document ACID transactions (MongoDB 4.0+) for complex operations
- Data Modeling: Embedding vs referencing based on access patterns, cardinality, and size
- Change Streams: Real-time data change notifications for event-driven architectures
Code Examples
Basic Connection and CRUD Operations
from pymongo import MongoClient
from pymongo.errors import DuplicateKeyError
from datetime import datetime
client = MongoClient("mongodb://localhost:27017/")
db = client["app_database"]
def create_user(user_data):
user_doc = {
"email": user_data["email"],
"name": user_data["name"],
"password_hash": user_data["password_hash"],
"created_at": datetime.utcnow(),
"updated_at": datetime.utcnow(),
"profile": user_data.get("profile", {})
}
result = db.users.insert_one(user_doc)
return str(result.inserted_id)
def get_user_by_email(email):
return db.users.find_one({"email": email})
def get_user_with_orders(user_id):
from bson import ObjectId
user = db.users.find_one({"_id": ObjectId(user_id)})
if user:
user["orders"] = list(db.orders.find({"user_id": ObjectId(user_id)}).sort("created_at", -1))
return user
def update_user_profile(user_id, profile_updates):
from bson import ObjectId
result = db.users.update_one(
{"_id": ObjectId(user_id)},
{"$set": {**profile_updates, "updated_at": datetime.utcnow()}}
)
return result.modified_count > 0
def delete_user(user_id):
from bson import ObjectId
with db.client.start_session() as session:
with session.start_transaction():
db.orders.delete_many({"user_id": ObjectId(user_id)}, session=session)
result = db.users.delete_one({"_id": ObjectId(user_id)}, session=session)
return result.deleted_count > 0
Aggregation Pipeline for Analytics
from bson import ObjectId
from datetime import datetime, timedelta
def get_sales_analytics(start_date, end_date):
pipeline = [
{"$match": {"created_at": {"$gte": start_date, "$lte": end_date}}},
{"$group": {
"_id": {"$dateToString": {"format": "%Y-%m-%d", "date": "$created_at"}},
"total_orders": {"$sum": 1},
"total_revenue": {"$sum": "$total"},
"avg_order_value": {"$avg": "$total"},
"unique_customers": {"$addToSet": "$user_id"}
}},
{"$project": {
"date": "$_id",
"total_orders": 1,
"total_revenue": 1,
"avg_order_value": 1,
"unique_customers": {"$size": "$unique_customers"}
}},
{"$sort": {"date": 1}}
]
return list(db.orders.aggregate(pipeline))
def get_top_products(limit=10):
pipeline = [
{"$unwind": "$items"},
{"$group": {
"_id": "$items.product_id",
"total_quantity": {"$sum": "$items.quantity"},
"total_revenue": {"$sum": {"$multiply": ["$items.quantity", "$items.price"]}}
}},
{"$lookup": {
"from": "products",
"localField": "_id",
"foreignField": "_id",
"as": "product"
}},
{"$unwind": "$product"},
{"$project": {
"name": "$product.name",
"total_quantity": 1,
"total_revenue": 1
}},
{"$sort": {"total_revenue": -1}},
{"$limit": limit}
]
return list(db.order_items.aggregate(pipeline))
def get_user_segmentation():
pipeline = [
{"$lookup": {
"from": "orders",
"localField": "_id",
"foreignField": "user_id",
"as": "orders"
}},
{"$project": {
"name": 1,
"email": 1,
"total_orders": {"$size": "$orders"},
"total_spent": {"$sum": "$orders.total"},
"last_order_date": {"$max": "$orders.created_at"}
}},
{"$addFields": {
"segment": {
"$switch": {
"branches": [
{"case": {"$gte": ["$total_orders", 10]}, "then": "premium"},
{"case": {"$gte": ["$total_orders", 5]}, "then": "regular"},
{"case": {"$gte": ["$total_orders", 1]}, "then": "occasional"}
],
"default": "new"
}
}
}}
]
return list(db.users.aggregate(pipeline))
def get_category_performance():
pipeline = [
{"$unwind": "$items"},
{"$lookup": {
"from": "products",
"localField": "items.product_id",
"foreignField": "_id",
"as": "product"
}},
{"$unwind": "$product"},
{"$group": {
"_id": "$product.category",
"total_sales": {"$sum": {"$multiply": ["$items.quantity", "$items.price"]}},
"total_quantity": {"$sum": "$items.quantity"},
"order_count": {"$sum": 1}
}},
{"$sort": {"total_sales": -1}}
]
return list(db.orders.aggregate(pipeline))
Complex Queries and Indexing
from pymongo import ASCENDING, DESCENDING, TEXT
def create_product_indexes():
db.products.create_index([("name", TEXT), ("description", TEXT)], default_language="english")
db.products.create_index([("category", ASCENDING), ("price", DESCENDING)])
db.products.create_index([("SKU", ASCENDING)], unique=True)
db.products.create_index([("tags", ASCENDING)])
db.products.create_index([("created_at", DESCENDING)])
def search_products(query, filters=None):
search_filter = {"$text": {"$search": query}}
if filters:
if "min_price" in filters:
search_filter.setdefault("$and", []).append({"price": {"$gte": filters["min_price"]}})
if "max_price" in filters:
search_filter.setdefault("$and", []).append({"price": {"$lte": filters["max_price"]}})
if "category" in filters:
search_filter["category"] = filters["category"]
return db.products.find(
search_filter,
{"score": {"$meta": "textScore"}}
).sort("score", {"$meta": "textScore"}).limit(50)
def find_nearby_stores(location, max_distance_meters=5000):
return db.stores.find({
"location": {
"$nearSphere": {
"$geometry": {"type": "Point", "coordinates": location},
"$maxDistance": max_distance_meters
}
}
})
def get_products_by_tags(tags, match_all=False):
operator = "$all" if match_all else "$in"
return db.products.find({"tags": {operator: tags}})
def get_inventory_alerts(threshold=10):
return list(db.products.aggregate([
{"$match": {"stock": {"$lte": threshold}}},
{"$project": {
"name": 1,
"SKU": 1,
"stock": 1,
"reorder_point": "$reorder_level",
"status": {
"$cond": {"if": {"$lte": ["$stock", 5]}, "then": "critical", "else": "low"}
}
}},
{"$sort": {"stock": 1}}
]))
Transactions and Batch Operations
from bson import ObjectId
from pymongo.errors import BulkWriteError
def create_order_with_inventory_check(user_id, items, shipping_address):
with db.client.start_session() as session:
with session.start_transaction():
for item in items:
product = db.products.find_one({
"_id": item["product_id"],
"stock": {"$gte": item["quantity"]}
}, session=session)
if not product:
raise ValueError(f"Insufficient stock for product {item['product_id']}")
order_doc = {
"user_id": ObjectId(user_id),
"items": items,
"total": sum(item["quantity"] * item["price"] for item in items),
"status": "pending",
"shipping_address": shipping_address,
"created_at": datetime.utcnow()
}
order_result = db.orders.insert_one(order_doc, session=session)
for item in items:
db.products.update_one(
{"_id": item["product_id"]},
{"$inc": {"stock": -item["quantity"]}},
session=session
)
return str(order_result.inserted_id)
def bulk_insert_products(products):
docs = []
for product in products:
docs.append({
"name": product["name"],
"SKU": product["SKU"],
"price": product["price"],
"category": product["category"],
"stock": product.get("stock", 0),
"tags": product.get("tags", []),
"created_at": datetime.utcnow()
})
try:
result = db.products.insert_many(docs, ordered=False)
return len(result.inserted_ids)
except BulkWriteError as e:
return e.details.get("nInserted", 0)
def update_prices_by_category(category, price_change_percent):
return db.products.update_many(
{"category": category},
{"$mul": {"price": 1 + price_change_percent / 100}}
).modified_count
def migrate_user_data():
pipeline = [
{"$match": {"profile.address": {"$exists": True}}},
{"$addFields": {
"address": {
"street": "$profile.address.street",
"city": "$profile.address.city",
"state": "$profile.address.state",
"zip": "$profile.address.zip_code"
}
}},
{"$unset": ["profile.address", "profile.address_old"]}
]
return db.users.update_many(pipeline, {})
Geospatial Queries and Array Operations
def create_store_location(name, address, coordinates):
db.stores.create_index([("location", "2dsphere")])
store_doc = {
"name": name,
"address": address,
"location": {"type": "Point", "coordinates": coordinates},
"hours": [
{"day": "Monday", "open": "09:00", "close": "21:00"},
{"day": "Tuesday", "open": "09:00", "close": "21:00"},
],
"services": ["pickup", "delivery", "installation"]
}
return db.stores.insert_one(store_doc).inserted_id
def search_stores_with_services(services):
return db.stores.find({"services": {"$all": services}})
def get_orders_with_multiple_items(min_items=3):
return db.orders.find({"$expr": {"$gte": [{"$size": "$items"], min_items]}})
def get_popular_tags():
return list(db.products.aggregate([
{"$unwind": "$tags"},
{"$group": {"_id": "$tags", "count": {"$sum": 1}}},
{"$sort": {"count": -1}},
{"$limit": 20}
]))
def calculate_cart_total(user_id):
pipeline = [
{"$match": {"user_id": ObjectId(user_id), "status": "active"}},
{"$unwind": "$items"},
{"$lookup": {
"from": "products",
"localField": "items.product_id",
"foreignField": "_id",
"as": "product"
}},
{"$unwind": "$product"},
{"$group": {
"_id": "$_id",
"items": {"$push": {
"name": "$product.name",
"quantity": "$items.quantity",
"price": "$items.price"
}},
"subtotal": {"$sum": {"$multiply": ["$items.quantity", "$items.price"]}}
}}
]
return list(db.carts.aggregate(pipeline))
Best Practices
- Design for Query Patterns: Model data based on how it will be queried, not just how it relates (embed vs reference)
- Use Appropriate Indexes: Create indexes based on actual query patterns; use explain() to analyze performance
- Implement Proper Error Handling: Use try-except blocks and handle DuplicateKeyError for unique constraint violations
- Use Projections Wisely: Limit returned fields with projections to reduce network overhead and memory usage
- Batch Operations for Bulk Data: Use bulk_write() for multiple operations to reduce round trips
- Implement Connection Pooling: MongoClient maintains connection pools; create one instance per application
- Use Transactions Judiciously: Multi-document transactions have overhead; use them only when needed
- Monitor with MongoDB Atlas or Ops Manager: Track performance metrics, slow queries, and index usage
- Implement Proper Authentication: Use SCRAM authentication, enable TLS/SSL, and follow principle of least privilege
- Plan for Scaling: Design sharding keys early; consider document size limits (16MB) and working set size