🧪 Lab 11: Monitoring & Performance¶

Topics: explain(), $indexStats, collStats, serverStatus, profiler

---

In [ ]:

from pymongo import MongoClient, ReadPreference
from pymongo.read_concern import ReadConcern
from pymongo.write_concern import WriteConcern
from pymongo.errors import ConnectionFailure
from bson import ObjectId
from datetime import datetime, timedelta, timezone
import pprint

USE_ATLAS = False
ATLAS_URI  = "mongodb+srv://<username>:<password>@<cluster>.mongodb.net/?retryWrites=true&w=majority"
DOCKER_URI = "mongodb://127.0.0.1:27017/?directConnection=true"

uri = ATLAS_URI if USE_ATLAS else DOCKER_URI
client = MongoClient(uri, serverSelectionTimeoutMS=5000)
try:
    client.admin.command("ping")
    print("✅ Connected to", "Atlas" if USE_ATLAS else "Docker MongoDB")
except ConnectionFailure as e:
    print("❌ Connection failed:", e)

db = client["mongo_labs"]
pp = pprint.PrettyPrinter(indent=2)

from pymongo import MongoClient, ReadPreference from pymongo.read_concern import ReadConcern from pymongo.write_concern import WriteConcern from pymongo.errors import ConnectionFailure from bson import ObjectId from datetime import datetime, timedelta, timezone import pprint USE_ATLAS = False ATLAS_URI = "mongodb+srv://<username>:<password>@<cluster>.mongodb.net/?retryWrites=true&w=majority" DOCKER_URI = "mongodb://127.0.0.1:27017/?directConnection=true" uri = ATLAS_URI if USE_ATLAS else DOCKER_URI client = MongoClient(uri, serverSelectionTimeoutMS=5000) try: client.admin.command("ping") print("✅ Connected to", "Atlas" if USE_ATLAS else "Docker MongoDB") except ConnectionFailure as e: print("❌ Connection failed:", e) db = client["mongo_labs"] pp = pprint.PrettyPrinter(indent=2)

explain() — Query execution¶

In [ ]:

plan = db.orders.find({"status":"delivered"}).explain("executionStats")
print("Stage:", plan["queryPlanner"]["winningPlan"]["stage"])
print("Docs examined:", plan["executionStats"]["totalDocsExamined"])
print("Docs returned:", plan["executionStats"]["totalDocsReturned"])
print("Time (ms):", plan["executionStats"]["executionTimeMillis"])

plan = db.orders.find({"status":"delivered"}).explain("executionStats") print("Stage:", plan["queryPlanner"]["winningPlan"]["stage"]) print("Docs examined:", plan["executionStats"]["totalDocsExamined"]) print("Docs returned:", plan["executionStats"]["totalDocsReturned"]) print("Time (ms):", plan["executionStats"]["executionTimeMillis"])

$indexStats — Index usage¶

In [ ]:

print("Index usage stats:")
for stat in db.orders.aggregate([{"$indexStats":{}}]):
    print(f"  {stat['name']:30s} accesses={stat['accesses']['ops']}"))

print("Index usage stats:") for stat in db.orders.aggregate([{"$indexStats":{}}]): print(f" {stat['name']:30s} accesses={stat['accesses']['ops']}"))

collStats — Collection size¶

In [ ]:

stats = db.command("collStats","orders")
print("=== orders collection ===" )
print(f"  Count: {stats.get('count',0)}")
print(f"  Storage: {stats.get('storageSize',0)} bytes")
print(f"  Index size: {stats.get('totalIndexSize',0)} bytes")
print(f"  Indexes: {len(stats.get('indexSizes',{}))}")

stats = db.command("collStats","orders") print("=== orders collection ===" ) print(f" Count: {stats.get('count',0)}") print(f" Storage: {stats.get('storageSize',0)} bytes") print(f" Index size: {stats.get('totalIndexSize',0)} bytes") print(f" Indexes: {len(stats.get('indexSizes',{}))}")

dbStats — Database stats¶

In [ ]:

db_stats = db.command("dbStats")
print("=== mongo_labs database ===" )
print(f"  Collections: {db_stats.get('collections',0)}")
print(f"  Objects: {db_stats.get('objects',0)}")
print(f"  Data size: {db_stats.get('dataSize',0)} bytes")

db_stats = db.command("dbStats") print("=== mongo_labs database ===" ) print(f" Collections: {db_stats.get('collections',0)}") print(f" Objects: {db_stats.get('objects',0)}") print(f" Data size: {db_stats.get('dataSize',0)} bytes")

serverStatus — Server metrics¶

In [ ]:

admin_db = client["admin"]
svr = admin_db.command("serverStatus")
print("=== Server Status ===" )
print(f"  Connections current: {svr['connections']['current']}")
print(f"  Connections available: {svr['connections']['available']}")
print(f"  Insert ops: {svr['opcounters']['insert']}")
print(f"  Query ops: {svr['opcounters']['query']}")

admin_db = client["admin"] svr = admin_db.command("serverStatus") print("=== Server Status ===" ) print(f" Connections current: {svr['connections']['current']}") print(f" Connections available: {svr['connections']['available']}") print(f" Insert ops: {svr['opcounters']['insert']}") print(f" Query ops: {svr['opcounters']['query']}")

currentOp — Running operations¶

In [ ]:

ops = admin_db.command("currentOp",{"active":True,"secs_running":{"$gt":1}})
if ops["inprog"]:
    for op in ops["inprog"]:
        print(f"  opid={op.get('opid')}, secs={op.get('secs_running')}")
else:
    print("✅ No long-running operations")

ops = admin_db.command("currentOp",{"active":True,"secs_running":{"$gt":1}}) if ops["inprog"]: for op in ops["inprog"]: print(f" opid={op.get('opid')}, secs={op.get('secs_running')}") else: print("✅ No long-running operations")

Profiler — Capture slow queries¶

In [ ]:

db.command("profile",1,slowms=100)
db.orders.find({"status":"delivered"}).sort("total",-1).toArray()
profiled = list(db.system.profile.find({}).sort("ts",-1).limit(5))
if profiled:
    for op in profiled[:3]:
        print(f"  {op.get('op')}: {op.get('millis')}ms examined={op.get('docsExamined')}")
db.command("profile",0)
print("✅ Profiler off")

db.command("profile",1,slowms=100) db.orders.find({"status":"delivered"}).sort("total",-1).toArray() profiled = list(db.system.profile.find({}).sort("ts",-1).limit(5)) if profiled: for op in profiled[:3]: print(f" {op.get('op')}: {op.get('millis')}ms examined={op.get('docsExamined')}") db.command("profile",0) print("✅ Profiler off")