Stores JSON objects in BSON format.
Javascript based. Allows to query in javascript style.
Master-Slave architecture - shards and replicasets
There is a router with a table of contents and shard keys using which it decides where to query the data and in some cases multiple shards.
mongos - process which manages cluster
client connects to mongos
> use recipe
switched to db recipe
> show dbs
admin 0.000GB
config 0.000GB
local 0.000GB
recipe 0.000GB
db.<collectionName>.insertOne({<entire json document to be inserted>}) -> this will dynamically create a collection
db.<collectionName>.find({"fieldToQuery":"valueOfFieldToQuery"}, {"filedstLimitOutput": 1})
.sort("fieldToSortBy": 1).limit(1).skip(1)
> show collections
recipe
> db.recipe.find({}, {"title": 1});
{ "_id" : ObjectId("5f8c85634e5ccd1948fb7611"), "title" : "Zucchini Brownies" }
{ "_id" : ObjectId("5f8c88a94e5ccd1948fb7612"), "title" : "Chicken Soft Tacos" }
{ "_id" : ObjectId("5f8c88ee4e5ccd1948fb7613"), "title" : "Pancakes" }
> db.recipe.find({"title" : "Pancakes"}, {"title": 1});
{ "_id" : ObjectId("5f8c88ee4e5ccd1948fb7613"), "title" : "Pancakes" }
> db.recipe.find({},{"title": 1}).sort({"title":1});
{ "_id" : ObjectId("5f8c88a94e5ccd1948fb7612"), "title" : "Chicken Soft Tacos" }
{ "_id" : ObjectId("5f8c88ee4e5ccd1948fb7613"), "title" : "Pancakes" }
{ "_id" : ObjectId("5f8c85634e5ccd1948fb7611"), "title" : "Zucchini Brownies" }
> db.recipe.find({},{"title": 1}).sort({"title":1}).limit(1);
{ "_id" : ObjectId("5f8c88a94e5ccd1948fb7612"), "title" : "Chicken Soft Tacos" }
> db.recipe.find({},{"title": 1}).sort({"title":1}).limit(1).skip(1);
{ "_id" : ObjectId("5f8c88ee4e5ccd1948fb7613"), "title" : "Pancakes" }
# nested objects can also be queried
> db.recipe.find({"ingredients.name" : "egg"}, {"title" : 1});
{ "_id" : ObjectId("5f8c85634e5ccd1948fb7611"), "title" : "Zucchini Brownies" }
{ "_id" : ObjectId("5f8c88ee4e5ccd1948fb7613"), "title" : "Pancakes" }
# querying arrays
> db.recipe.find({"tags" : "easy"}, {"title" : 1});
{ "_id" : ObjectId("5f8c85634e5ccd1948fb7611"), "title" : "Zucchini Brownies" }
{ "_id" : ObjectId("5f8c88a94e5ccd1948fb7612"), "title" : "Chicken Soft Tacos" }
# match both entries in an array
> db.recipe.find({"tags" : {$all: ["easy","mexican"]}}, {"title" : 1});
{ "_id" : ObjectId("5f8c88a94e5ccd1948fb7612"), "title" : "Chicken Soft Tacos" }
# match either entries in an array
> db.recipe.find({"tags" : {$in: ["easy","mexican"]}}, {"title" : 1});
{ "_id" : ObjectId("5f8c85634e5ccd1948fb7611"), "title" : "Zucchini Brownies" }
{ "_id" : ObjectId("5f8c88a94e5ccd1948fb7612"), "title" : "Chicken Soft Tacos" }
#using expression
> db.recipe.find({$and :[{"ingredients.name" : "egg"}, {"ingredients.name" : "milk"}]}, {"title" : 1});
{ "_id" : ObjectId("5f8c88ee4e5ccd1948fb7613"), "title" : "Pancakes" }
$regex - for doing a regex search on a field
can store arrays, nested documents
comparison operators:
$eq, $lt, $lte, $gt, $gte, $ne, $in, $nin
logical operators:
$and, $or, $not
evalution:
$exists - to match documents with specified field
$where - documents satisfying javascript expression
it even have geospatial evaluation operators - $geoWithin, $geoIntersects etc
db.<collectionName>.updateOne({"fieldToQuery":"valueOfFieldToQuery"}, {$set :{"filedstLimitOutput": 1}});
> db.recipe.updateOne({"title" : "Zucchini Brownies" }, {$set: {"title" : "Zucchini Browniesss" }});
{ "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 }
$push $pull can be used for updating data in an array
# for getting the execution statistics, explain("executionStats") can be used
db.recipe.find({"tags" : {$in: ["easy","mexican"]}}, {"title" : 1}).explain("executionStats");
Reference documentation - https://docs.mongodb.com/manual/reference
sample_json = {
"title":"Zucchini Brownies",
"calories_per_serving":271,
"comments": [{
"body": "This is really gross.",
"date": {
"$date": "2020-09-07T18:42:30.000Z"
},
"name": "Caderyn Jenkins",
"user_id": 1
}, {
"body": "Who thought of this? It's so bad.",
"date": {
"$date": "2000-02-03T18:42:30.000Z"
},
"name": "Grace Hopper",
"user_id": 2
}],
"cook_time":32,
"desc":"Don't worry, they won't turn out green",
"directions":[
"Combine brownie mix with other ingredients",
"Bake as it says on box",
"Don't actually make or eat this."
],
"ingredients":[
{
"amount":{
"quantity":1,
"unit":"cup"
},
"name":"butter"
},
{
"amount":{
"quantity":2,
"unit":null
},
"name":"egg"
},
{
"amount":{
"quantity":0.75,
"unit":"cup"
},
"name":"plain yogurt"
},
{
"amount":{
"quantity":0.75,
"unit":"cup"
},
"name":"shredded zucchini"
},
{
"amount":{
"quantity":0.75,
"unit":"cup"
},
"name":"chocolate chips (semisweet)"
},
{
"amount":{
"quantity":3,
"unit":"lbs"
},
"name":"creamy peanut butter"
},
{
"amount":{
"quantity":1,
"unit":null
},
"name":"brownie mix"
}
],
"prep_time":12,
"rating":[
1,
1,
1,
1,
5
],
"rating_avg":1.8,
"servings":12,
"tags":[
"sweets",
"easy"
],
"type":"Dessert"
}
db.recipe.insertOne(sample_json);
Start/Stop mongod services in Mac:
brew services start mongodb-community@4.4
brew services stop mongodb-community@4.4
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