+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Drop persons table and recreate it
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

db.persons.drop()

db.persons.insert ( {
	name: {first: 'Harish', last: 'Chandra'},
	gender: 'M',
	yearOfBirth: 1962,
	livesIn: 'Mumbai',
	countriesVisited: ['India', 'Singapore', 'Thailand', 'United Kingdom', 'Spain', 'Denmark', 'United States of America'],
	languages: [
		{name: 'Hindi', proficiency: 'Fluent'},
		{name: 'English', proficiency: 'Fluent'},
		{name: 'Sanskrit', proficiency: 'Intermediate'} ]
} )

db.persons.insert ( {
	name: {first: 'Zoa', last: 'Hendrik'},
	gender: 'F',
	yearOfBirth: 1988,
	livesIn: 'Barcelona',
	countriesVisited: ['Spain', 'Denmark', 'France'],
	languages: [
		{name: 'Spanish', proficiency: 'Fluent'},
		{name: 'Catalan', proficiency: 'Fluent'},
		{name: 'English', proficiency: 'Intermediate'} ],
	married: 'No'
} )

db.persons.insert ( {
	name: {first: 'Narayan', last: 'Sundaram'},
	gender: 'M',
	yearOfBirth: 1960,
	livesIn: 'Jaipur',
	counriesVisited: ['India', 'United States of America', 'Netherlands', 'China'],
	languages: [
		{name: 'Tamil', proficiency: 'Fluent'},
		{name: 'English', proficiency: 'Fluent'},
		{name: 'Hindi', proficiency: 'Intermediate'},
		{name: 'Chinese', proficiency: 'Intermediate'} ],
	married: 'Yes'
} )

db.persons.insert ( {
	name: {first: 'Shailesh', last: 'mark'},
	gender: 'M',
	yearOfBirth: 1962,
	livesIn: 'Singapore',
	countriesVisited: ['India', 'Singapore', 'China', 'Taiwan', 'United States of America', 'Sri Lanka', 'Mayalsia', 'Australia'],
	languages: [
		{name: 'Hindi', proficiency: 'Fluent'},
		{name: 'English', proficiency: 'Fluent'} ]
} ) 

db.persons.insert ( {
	name: {first: 'Mark', last: 'Smith'},
	gender: 'M',
	livesIn: 'Chicago',
	countriesVisited: ['United States of America', 'Canada', 'France', 'Spain', 'India', 'Australia'],
	languages: [ {name: 'English', proficiency: 'Fluent'} ]
} )

db.persons.insert ( {
	name: {first: 'Rita', last: 'Chauhan'},
	gender: 'F',
	yearOfBirth: 1989,
	livesIn: 'Mumbai',
	countriesVisited: ['India'],
	languages: [
		{name: 'Hindi', proficiency: 'Fluent'},
		{name: 'English', proficiency: 'Fluent'} ],
	married: 'No'
} )

db.persons.insert ( {
	name: {first: 'Liza', last: 'Bordelon'},
	gender: 'F',
	yearOfBirth: 1971,
	livesIn: 'Minneapolis',
	countriesVisited: ['United States of America', 'Canada'],
	languages: [
		{name: 'English', proficiency: 'Fluent'},
		{name: 'French', proficiency: 'Fluent'},
		{name: 'German', proficiency: 'Intermediate'},
		{name: 'Greek', proficiency: 'Intermediate'},
		{name: 'Latin', proficiency: 'Intermediate'},
		{name: 'Sanskrit', proficiency: 'Beginner'} ]
} )

db.persons.insert ( {
	name: {first: 'Jenny', last: 'Jones'},
	gender: 'F',
	yearOfBirth: 1985,
	livesIn: 'Oxford',
	countriesVisited: ['United Kingdom'],
	languages: [ {name: 'English', proficiency: 'Fluent'} ],
	married: 'No'
} )

db.persons.insert ( {
	name: {first: 'Sapna', last: 'Chetri'},
	gender: 'F',
	yearOfBirth: 1989,
	livesIn: 'Siliguri',
	countriesVisited: ['India'],
	languages: [
		{name: 'Nepali', proficiency: 'Fluent'},
		{name: 'Hindi', proficiency: 'Fluent'},
		{name: 'English', proficiency: 'Intermediate'} ],
	married: 'No'
} )

db.persons.insert ( {
	name: {first: 'Jenny', middle: 'H', last: 'Jones'},
	gender: 'F',
	yearOfBirth: 1988,
	livesIn: 'London',
	countriesVisited: ['United Kingdom'],
	languages: [ {name: 'English', proficiency: 'Fluent'} ],
	married: 'Yes'
} )

db.persons.insert ( {
	name: {first: 'Lakhpa', last: 'Sherpa'},
	gender: 'M',
	yearOfBirth: 1989,
	lievsIn: 'Gangtok',
	countriesVisited: ['India'],
	languages: [
		{name: 'Nepali', proficiency: 'Fluent'},
		{name: 'English', proficiency: 'Fluent'},
		{name: 'Hindi', proficiency: 'Intermediate'} ],
	married: 'No'
} )

db.persons.insert ( {
	name: {first: 'Anita', last: 'Gogia'},
	gender: 'F',
	yearOfBirth: 1965,
	livesIn: 'New Delhi',
	countriesVisited: ['India', 'United Kingdom', 'Canada', 'United States of America'],
	languages: [
		{name: 'Hindi', proficiency: 'Fluent'},
		{name: 'Punjabi', proficiency: 'Fluent'},
		{name: 'English', proficiency: 'Fluent'} ],
	married: 'Yes'
} )

db.persons.insert ( {
	name: {first: 'Neeharika', last: 'Chauhan'},
	gender: 'F',
	yearOfBirth: 1988,
	livesIn: 'Jaipur',
	countriesVisited: ['India'],
	languages: [
		{name: 'Hindi', proficiency: 'Fluent'},
		{name: 'English', proficiency: 'Intermediate'} ],
	married: 'No'
} )

db.persons.insert ( {
	name: {first: 'Nancy', last: 'Karin'},
	gender: 'F',
	yearOfBirth: 1992,
	livesIn: 'Montreal',
	countriesVisited: ['Canada', 'United States of America'],
	languages: [
		{name: 'English', proficiency: 'Fluent'},
		{name: 'French', proficiency: 'Fluent'},
		{name: 'German', proficiency: 'Intermediate'},
		{name: 'Greek', proficiency: 'Intermediate'},
		{name: 'Latin', proficiency: 'Intermediate'},
		{name: 'Sanskrit', proficiency: 'Beginner'} ]
} )

db.persons.count()

-- Find all females
db.persons.find( {gender: 'F'} )
db.persons.find( {gender: 'F'} ).pretty()
db.persons.find( {gender: 'F'} ).count()
db.persons.find( {gender: 'F'}, {name: 1} )
db.persons.find( {gender: 'F'}, {name: 1, _id: 0} )
db.persons.find( {gender: 'F'}, {name: true, _id: false} )
db.persons.find( {gender: 'F'}, {name: 1, yearOfBirth: 1} )
db.persons.find( {gender: 'F'}, {name: 1, yearOfBirth: 1, _id: 0} )
db.persons.find( {gender: 'F'}, {name: 1, yearOfBirth: 1, _id: 0, married: 0} ) // This gives an error: "cannot mix including and excluding fields".

-- Find names of all persons
db.persons.find (
	{},
	{name: 1, _id: 0}
)

-- Find all people living in Mumbai or Jaipur
db.persons.find ( 
	{livesIn: {$in: ['Mumbai', 'Jaipur'] } } 
).pretty()

db.persons.find ( 
	{livesIn: {$in: ['Mumbai', 'Jaipur'] } },
	{name: 1, _id: 0} 
).pretty()

-- All people born before 1980
db.persons.find (
	{yearOfBirth: {$lt: 1980} },
	{name: 1, yearOfBirth: 1, _id: 0}
).pretty()

-- All persons not living in Jaipur
db.persons.find (
	{livesIn: {$ne: 'Jaipur'} },
	{name: 1, livesIn: 1, _id: 0}
).pretty()

-- All persons who have visited India, United States of America and Singapore
db.persons.find (
	{countriesVisited: {$all: ['India', 'United States of America', 'Singapore'] } },
	{name: 1, countriesVisited: 1, _id: 0}
).pretty()

-- Find all persons with first name as 'Sapna'
db.persons.find (
	{'name.first' : 'Sapna'},
	{name: 1, _id: 0}
).pretty()

-- Find all persons whose 'name' subdocument has exactly the same fields, with the given values, in the same order
db.persons.find (
	{name: {first: 'Jenny', last: 'Jones'} },
	{name: 1, _id: 0}
)

-- Find all persons with 'Jenny' as first name and 'Jones' as last name
db.persons.find (
	{'name.first': 'Jenny', 'name.last': 'Jones'},
	{name: 1, _id: 0}
)

-- Find all persons who have visited India
db.persons.find (
	{countriesVisited: 'India'},
	{name: 1, countriesVisited: 1, _id: 0}
).pretty()

-- Find all persons who have visited Canada and United States of America. But the following query returns only those documents
-- where the data is exactly as given below and in the same order.
db.persons.find (
	{countriesVisited: ['Canada', 'United States of America'] },
	{name: 1, countriesVisited: 1, _id: 0}
).pretty()

-- This is the correct query. Though if you were looking for those people who have visited only these two countries and 
-- no other country, this will not work.
db.persons.find ( {countriesVisited: {$all: ['Canada', 'United States of America'] } }, {name: 1, _id: 0} )

-- Find all persons whose first country visited is India
db.persons.find (
	{'countriesVisited.0': 'India'},
	{name: 1, countriesVisited: 1, _id: 0}
).pretty()

-- Find all persons whose first language is 'English'
db.persons.find (
	{'languages.0.name': 'English'},
	{name: 1, languages: 1, _id: 0}
)

-- Find all persons who know English
db.persons.find (
	{'languages.name': 'English'},
	{name: 1, languages: 1, _id: 0}
)

-- Find all persons who either live in Mumbai or have visited India
db.persons.find (
	{$or: [
		{livesIn: 'Mumbai'},
		{countriesVisited: 'India'}
	] },
	{name: 1, livesIn: 1, countriesVisited: 1, _id: 0}
).pretty()

-- Find all persons who have visited India or know Hindi
db.persons.find (
	{$or: [
		{countriesVisited: 'India'},
		{'languages.name': 'Hindi'}
	] },
	{name: 1, countriesVisited: 1, languages: 1, _id: 0}
).pretty()

-- Find all persons who have visited India and know Hindi
db.persons.find (
	{$and: [
		{countriesVisited: 'India'},
		{'languages.name': 'Hindi'}
	] },
	{name: 1, countriesVisited: 1, languages: 1, _id: 0}
).pretty()

-- Find all persons who are fluent in English.
-- The following is incorrect: it will find all persons who know English and are fluent in any one langauge.
db.persons.find ( {$and: [
	{'languages.name': 'English'}, 
	{'languages.proficiency': 'Fluent'}
] }, {name: 1, _id: 0} )

-- What we need is to compare language name and proficiency level within the same array element. This is the right query:
db.persons.find (
	{languages: {$elemMatch: {name: 'English', proficiency: 'Fluent'} } },
	{name: 1, languages: 1, _id: 0}
).pretty()

-- Find all persons with fluency in English or Hindi
db.persons.find (
	{languages: {$elemMatch: {
		name: {$in: ['English', 'Hindi'] }, 
		proficiency: 'Fluent'
	} } },
	{name: 1, languages: 1, _id: 0}
).pretty()

-- Find all persons who have visited India and are fluent in Hindi
db.persons.find (
	{countriesVisited: 'India', languages: {$elemMatch: {name: 'Hindi', proficiency: 'Fluent'} } },
	{name: 1, countriesVisited: 1, languages: 1, _id: 0}
)

-- All males born before 1970 and all females born before 1980.
db.persons.find (
	{$or: [
		{gender: 'M', yearOfBirth: {$lt: 1970} },
		{gender: 'F', yearOfBirth: {$lt: 1980} }
	] },
	{name: 1, gender: 1, yearOfBirth: 1, _id: 0}
)

-- For all females, return their name and the first three countries visited by them
db.persons.find ( 
	{gender: 'F'},
	{name: 1, countriesVisited: {$slice: 3}, _id: 0}
)

-- Show all persons, sorted in ascending order of their year of birth
db.persons.find(
	{},
	{name: 1, yearOfBirth: 1, _id: 0}
).sort ( {yearOfBirth: 1} )

-- Show all persons, sorted in ascending order of their year of birth; suppress people with no yearOfBirth available.
db.persons.find (
	{yearOfBirth: {$exists: true} },
	{name: 1, yearOfBirth: 1, _id: 0}
).sort ( {yearOfBirth: 1} )

-- Show all persons, sorted in descending order of their year of birth
db.persons.find (
	{yearOfBirth: {$exists: true} },
	{name: 1, yearOfBirth: 1, _id: 0}
).sort ( {yearOfBirth: -1} )

-- Show all persons, sorted by last name and then first name
db.persons.find (
	{},
	{name: 1, _id: 0}
).sort ( {'name.last': 1, 'name.first': 1} )

-- Show persons, sorted by last name and then first name, limiting to first five people
db.persons.find (
	{},
	{name: 1, _id: 0}
).sort ( {'name.last': 1, 'name.first': 1} ).limit (5)


-- The following also gives the same output even though limit is written before sort. MongoDB shell always applies
-- limit clause after sort clause.
db.persons.find ( {}, {name: 1, _id: 0} ).limit(5).sort ( {'name.last': 1, 'name.first': 1} )

-- Show persons, sorted by last name and then first name, limiting to 6-10th persons only
db.persons.find (
	{},
	{name: 1, _id: 0}
).sort ( {'name.last': 1, 'name.first': 1} ).skip(5).limit (5)

-- Find and return only one document for a condition
db.persons.findOne ( {gender: 'F'}, {name: 1, _id: 0} )

-- The following, however, is an error: sort, limit, skip are not applicable with findOne.
db.persons.findOne ( {gender: 'F'}, {name: 1, _id: 0} ).sort ( {'yearOfBirth': 1} )

-- Specifying the _id field

db.persons.insert ( {_id: 101, name: {first: 'Robinson', last: 'Crusoe'} } )

-- Duplicate key error:
db.persons.insert ( {_id: 101, name: {first: 'Jonathan', middle: 'Livingstone', last: 'Seagull'} } )

-- _id can be a document itself
db.persons.insert ( {_id: {name: {first: 'Mary', last: 'Kym'}}, gender: 'F'})

-- Update. The following is bad as after this command the document only has the "married" field.
db.persons.update ( 
	{name: {first: 'Nancy', last: 'Karin'} },
	{married: 'Y'}
)
-- Let's reset it first to the original data:
db.persons.remove( {"_id" : ObjectId("523c0c8c378c940550e7cb43") } )
db.persons.insert ( {
	name: {first: 'Nancy', last: 'Karin'},
	gender: 'F',
	yearOfBirth: 1992,
	livesIn: 'Montreal',
	countriesVisited: ['Canada', 'United States of America'],
	languages: [
		{name: 'English', proficiency: 'Fluent'},
		{name: 'French', proficiency: 'Fluent'},
		{name: 'German', proficiency: 'Intermediate'},
		{name: 'Greek', proficiency: 'Intermediate'},
		{name: 'Latin', proficiency: 'Intermediate'},
		{name: 'Sanskrit', proficiency: 'Beginner'} ]
} )
db.persons.update ( 
	{name: {first: 'Nancy', last: 'Karin'} },
	{name: {first: 'Nancy', last: 'Karin'},
	gender: 'F',
	yearOfBirth: 1992,
	livesIn: 'Montreal',
	countriesVisited: ['Canada', 'United States of America'],
	languages: [
		{name: 'English', proficiency: 'Fluent'},
		{name: 'French', proficiency: 'Fluent'},
		{name: 'German', proficiency: 'Intermediate'},
		{name: 'Greek', proficiency: 'Intermediate'},
		{name: 'Latin', proficiency: 'Intermediate'},
		{name: 'Sanskrit', proficiency: 'Beginner'} ],
	married: 'Y' 
	}
)
-- But this is cumbersome. Better would be:
db.persons.update ( 
	{name: {first: 'Nancy', last: 'Karin'} },
	{$set: {married: 'N'} }
)

-- There is no such record, so collections remains unaffected, no error is returned either.
db.persons.update (
	{name: {first: 'Merilyn', last: 'Holmes'} },
	{$set: {gender: 'F', yearOfBirth: 1997, married: 'N'} }
)
-- This illustrates upsert operation
db.persons.update (
	{name: {first: 'Merilyn', last: 'Holmes'} },
	{$set: {gender: 'F', yearOfBirth: 1997, married: 'N'} },
	{upsert: true}
)

-- Single record update
db.persons.update (
	{'countriesVisited.0': 'India'},
	{$set: {nationality: 'Indian'} }
)
-- Multiple records update
db.persons.update (
	{'countriesVisited.0': 'India'},
	{$set: {nationality: 'Indian'} },
	{multi: true}
)

-- Remove a field from a document
db.persons.update (
	{name: {first: 'Nancy', last: 'Karin'} },
	{$unset: {married: 1} }
)

-- Set the first language of Nancy Karin to Portugese
db.persons.update (
	{name: {first: 'Nancy', last: 'Karin'} },
	{$set: {'languages.0.name': 'Portugese'} }
)

-- Just a placeholder for a frequent query. Not required to be part of documentation.
db.persons.find ({'name.first': 'Rita', 'name.last': 'Chauhan'} ).pretty()

-- Change Nancy Karin's language from German to Italian
db.persons.update (
	{'name.first': 'Nancy', 'name.last': 'Karin', 'languages.name': 'German'},
	{$set: {'languages.$.name': 'Italian'} }
)

-- Change Italian back to German, and make her fluent in German
db.persons.update ( 
	{name: {first: 'Nancy', last: 'Karin'}, 'languages.name': 'Italian'},
	{$set: {'languages.$': {name: 'German', proficiency: 'Expert'} }
} )

-- Adding Beginner level proficiency in Spanish for Rita Chauhan
db.persons.update (
	{'name.first': 'Rita', 'name.last': 'Chauhan'},
	{$push: {languages: {name: 'Spanish', proficiency: 'Beginner' } } }
)

-- Increment / set a field value

db.persons.update (
	{'name.first': 'Rita', 'name.last': 'Chauhan'},
	{$inc: {children: 1} }
)

-- Renaming a field.
db.persons.find ( {livesIn: 'Gangtok'} )
-- The above does not find a record. Reason: wrongly spelt field name as 'lievsIn' for one record. Let's fix that
db.persons.update (
	{},
	{$rename: {'lievsIn': 'livesIn'}},
	{multi: true}
)

-- Similarly, subdocument fields can be renamed also
db.persons.update (
	{},
	{$rename: {'name.first': 'name.fname'} },
	{multi: true}
)
-- Roll it back
db.persons.update (
	{},
	{$rename: {'name.fname': 'name.first'} },
	{multi: true}
)

-- Renaming multiple field names
db.persons.update (
	{},
	{$rename: {'name.first': 'name.fname', 'name.last': 'name.lname', yearOfBirth: 'birthYear'} },
	{multi: true}
)
-- Roll it back
db.persons.update (
	{},
	{$rename: {'name.fname': 'name.first', 'name.lname': 'name.last', birthYear: 'yearOfBirth'} },
	{multi: true}
)

-- Fields can be renamed / moved outside a subdocument an vice-verse also.
db.persons.update (
	{},
	{$rename: {'name.first': 'firstname', 'name.last': 'lastname'} },
	{multi: true}
)
-- Drop the empty "name" subdocument.
db.persons.update (
	{},
	{$unset: {name: 'anyjunkcanbegivenhere doesnotmatter'} },
	{multi: true}
)
-- Roll back everything.
db.persons.update (
	{},
	{$rename: {firstname: 'name.first', lastname: 'name.last'} },
	{multi: true}
)
		
-- Narayan Sundaram, Rita Chauhan and Liza Bordelon have enrolled for Sanskrit classes, so they should all be marked as having
-- beginner level proficiency in Sanskrit. Out of these Liza Bordelon already has this, so should not be duplicated.
db.persons.update (
	{name: {$in: [
		{first: 'Narayan', last: 'Sundaram'},
		{first: 'Rita', last: 'Chauhan'},
		{first: 'Liza', last: 'Bordelon'}
	] } },
	{$addToSet: {languages: {name: 'Sanskrit', proficiency: 'Beginner'} } },
	{multi: true}
)

-- Add multiple languages to Neeharika Chauhan

db.persons.update ( 
	{'name.first': 'Neeharika', 'name.last': 'Chauhan'}, 
	{$push: 
		{languages: 
			{$each: [
				{name: 'Marathi', proficiency: 'Fluent'},
				{name: 'Gujrati'},
				{name: 'Punjabi', proficiency: 'Intermediate'}
] } } } )

-- Remove the last language for Nancy Karin
db.persons.update ( {'name.first': 'Nancy', 'name.last': 'Karin'}, {$pop: {languages: 1}})

-- Remove the first language for Nancy Karin
db.persons.update ( {'name.first': 'Nancy', 'name.last': 'Karin'}, {$pop: {languages: -1}})

-- Add languages for Nancy Karin and keep the data sorted

db.persons.update ( 
	{'name.first': 'Nancy', 'name.last': 'Karin'},
	{$push: {languages: {$each: [
		{name: 'Marathi', proficiency: 'Beginner'},
		{name: 'Gujrati', proficiency: 'Beginner'} ],
		$sort: {name: 1} } } }
)

-- Add some more languages for Nancy Karin, sort the data, and keep only the first three

db.persons.update ( 
	{'name.first': 'Nancy', 'name.last': 'Karin'},
	{$push: {languages: {$each: [
		{name: 'Sindhi', proficiency: 'Beginner'},
		{name: 'Tullu', proficiency: 'Beginner'} ],
		$sort: {name: 1}, $slice: 3 } } }
)

-- For all documents in the 'person” collection, we want the array “languages” to be sorted by language name. 
		
db.persons.update ( {},
	{$push: {languages: {$each: [], $sort: {name: 1} } } },
	{multi: true}
)

-- save operation
db.persons.save ( {name: {first: 'Jonathan', middle: 'Livingstone', last: 'Seagull'} } )
db.persons.save ( {_id: 102, name: {first: 'Vishnudutt', last: 'mark'} } )
db.persons.save ( {_id: 102, gender: 'M'} )
db.persons.save ( {_id: 102, name: {first: 'Vishnudutt', last: 'mark'}, gender: 'M'} )

-- findAndModify
db.persons.findAndModify ( {
	query: {$and: [{'name.first': 'Zoa'}, {'name.last': 'Hendrik'}]},
	remove: true,
	update: {$set: {livesIn: 'Madrid'} }
} )

db.persons.findAndModify ( {
	query: {'name.first': 'Zoa'},
	update: {$set {yearOfBirth: 1950} }
} )

-- Remove all males
db.persons.remove ( {gender: 'M'} )
-- Drop the collection; copy all data back into the collection

-- Remove just one male
db.persons.remove ( {gender: 'M'}, 1)

-- Remove all documents
db.persons.remove()
-- Better to drop the collection
db.persons.drop()

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Schema design
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

-- Blog project

db.users.insert ( {_id: "andrew", name: {first: "Andrew", last: "Weiss"}, email: "andrew@example.com"} )
db.users.insert ( {_id: "bharat", name: {first: "Bharat", last: "Kumar"}, email: "bharat@example.com"} )
db.users.insert ( {_id: "charlie", name: {first: "Charlie", last: "Gordon"}, email: "charlie@example.com"} )
db.users.insert ( {_id: "dilshad", name: {first: "Dilshad", last: "Khan"}, email: "dilshad@example.com"} )
db.users.insert ( {_id: "espicioza", name: {first: "Espicioza"}, email: "espy@example.com"} )
db.users.insert ( {_id: "froze", name: {first: "Feroze", last: "Sheikh"}, email: "froze@example.com"} )
db.users.insert { {_id: "grv", name: {first: "Gurvinder", last: "Singh"}, email: "gurvindersingh@example.com"} )
db.users.insert ( {_id: "hari", name: {first: "harish", last: "pande"}, email: "hpande@example.com"} )
db.users.insert ( {_id: "isabelle", name: {first: "isabelle"}, email: "isabelle@example.com"} )
db.users.insert ( {_id: "jc", {name: {first: "janet", last: "coelho"}, email: "jcoelho@example.com"} )

-- Relational style design

db.posts.insert ( {
	_id: 1,
	title: "My First Post",
	author: "charlie",
	date: new Date ("25-Apr-2014"),
	post: "This is my first post and I have no idea what to write"
} ) 

db.comments.insert( {
	_id: 1,
	postid: 1,	
	author: "andrew",
	comment: "this is funny",
	order: 1
} )

--------- Right design

db.posts.insert ( {
	_id: 1,
	title: "My First Post",
	author: "charlie",
	date: new Date ("25-Apr-2014"),
	post: "This is my first post and I have no idea what to write",
	comments: [
		{user: "andrew", comment: "this is funny"},
		{user: "dilshad", comment: "Welcome to the world of blogging, Charlie"}
	]
} ) 

db.citizens.insert ( {name: "kamal", city: "Mumbai"} )
db.cities.insert ( {_id: "Mumbai", population: "1.4 million"} )


db.students.insert ( {_id: 1, name: "Amar", courses: [2, 3, 4] } )
db.students.insert ( {_id: 2, name: "Akbar", courses: [1, 2] } )
db.students.insert ( {_id: 3, name: "Anthony"} )
db.students.insert ( {_id: 4, name: "Seeta", courses: [1, 4] } )
db.students.insert ( {_id: 5, name: "Geeta", courses: [3] } )

db.courses.insert ( {_id: 1, title: "African History", students: [2, 4] } )
db.courses.insert ( {_id: 2, title: "Anthropology", students: [1, 2] } )
db.courses.insert ( {_id: 3, title: "Indian Constitution", students: [1, 5] } )
db.courses.insert ( {_id: 4, title: "European Geography", students: [1, 4] } )
db.courses.insert ( {_id: 5, title: "Space Exploration"} )


db.categories.insert ( {_id: 1, name: "Clothing and accessories"} )
db.categories.insert ( {_id: 2, name: "Boys", ancestors: [1] } )
db.categories.insert ( {_id: 3, name: "Shirts", ancestors: [1, 2] } )

db.products.insert ( {_id: 1, name: "612 Ivy League Boys Shirts", price: 799, category: 3} )

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Schema design: Event Logger
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

db.events.insert ( {host: '127.0.0.1', user: 'amar', time: ISODate("2015-05-01T20:06:17Z"), path: '/cis/cis.pdf', request: 'GET /cis/cis.pdf HTTP/1.0', status: 200, response_size: 2103} )

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Capped collection
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

db.createCollection ('eventlog', {capped: true, size: 64*1024, max: 32} )
db.eventlog.insert ( {description: 'some dummy event'})
db.eventlog.insert ( {description: 'another dummy event'})
db.eventlog.find().sort( {natural: -1})

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Indexes
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

db.persons.ensureIndex ( {livesIn: 1} )
db.persons.ensureIndex ( {yearOfBirth: 1} )
db.persons.getIndexes ()
db.system.indexes.find()
db.persons.dropIndex ( {yearOfBirth: 1} )
db.persons.ensureIndex ( {yearOfBirth: -1} )

db.persons.ensureIndex ( {gender: 1, yearOfBirth: -1} )
db.persons.ensureIndex ( {name: 1} )
db.persons.ensureIndex ( {'name.last': 1, 'name.first': 1, yearOfBirth: -1} )
db.persons.ensureIndex ( {married: 1}, {sparse: true} )
db.persons.ensureIndex ( {name: 1}, {unique: true} )
db.persons.ensureIndex ( {'name.last': 1, 'name.first': 1}, {unique: true} ) -- fails as there are two Jenny Jones'es.
db.persons.ensureIndex ( {'name.last': 1, 'name.first': 1}, {unique: true, dropDups: true} )
db.persons.ensureIndex ( {'name.last': 1}, {background: true} )

db.persons.find ( {livesIn: 'Mumbai'}, {name: 1} ).explain()
db.persons.find ( {}, {name:1} ).sort ( {'name.last': 1} ).explain()
db.persons.find ( {}, {name: 1} ).sort ( {'name.first': 1} ).explain()
db.persons.find ( {}, {'name.last': 1} ).sort ( {'name.last': 1} ).explain()
db.persons.find ( {}, {'name.last': 1, gender: 1, 'name.first': 1} ).hint ( {'name.last': 1, 'name.first': 1} ).explain()
db.persons.find ( {}, {'name.last': 1} ).sort ( {'name.last': 1} ).hint ( {$natural: 1} ).explain()

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Replica Set, on one physical machine, different processes
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

-- create folders c:\data\rs1\rs1.1, c:\data\rs1\rs1.2, c:\data\rs1\rs1.3 

-- In three separate windows, run the following commands:
mongod --port 27001 --dbpath c:\data\rs1\rs1.1 --replSet rs1
mongod --port 27002 --dbpath c:\data\rs1\rs1.2 --replSet rs1
mongod --port 27003 --dbpath c:\data\rs1\rs1.3 --replSet rs1

-- In another window, open mongo shell and connect to the first mongod instance:
mongo --port 27001

-- Initiate the replicata set
rsconf = {
	_id: "rs1",
	members: [
		{_id: 1, host: "localhost:27001"}
	] }

rs.initiate (rsconf)
rs.conf ()
rs.add ("localhost:27002")
rs.add ("localhost:27003")
rs.status()

-- You may insert some documents using the mongo shell.
db.persons.count()

-- In another window, open mongo shell and connect to the second mongod instance:
mongo --port 27002
-- The following, however, will give error as this is not a primary
db.persons.count()
-- Try to insert a record, will fail also
-- However, you may read from the secondary:
rs.slaveOk()
-- Now the following works
db.persons.count()

-- In another window, open mongo shell and connect to the second mongod instance:
mongo --port 27003
db.persons.count()
rs.slaveOk()
db.persons.count()

-- Stop the primary mongod instance on port 27001

-- Come to mongo shell connected to 27001 and the following commands give error as the corresponding server is down.
rs.status()
db.persons.count()

-- Come to mongo shell connected to 27002 and 27003 and give the same commands
rs.status()
db.persons.count()

-- In the new primary mongo shell insert one record
db.persons.insert ( {name: {first: 'Eva'} } )
db.persons.count()

-- Start mongod on 27001 again
mongod --port 27001 --dbpath c:\data\rs1\rs1.1 --replSet rs1
-- and all is well again.

-- In case of problem:
rs.reconfig (rsconf, {force: true} )

-- We want to make 27002 as primary. For this we can make current primary crash or step down, but in an election 
-- there is no guarantee that 27002 will be elected. So we set priorities:
rsconfig = rs.conf ()
rsconfig.members [0].priority = 2
rsconfig.members [1].priority = 3
rsconfig.members [2].priority = 1
rs.reconfig (rsconfig)

-- Without changing priorities, if you want the primary to step down temporarily
rs.stepDown ()
-- Later, to make the highest priority server primary again, go to the new primary and stepDown there:
rs.stepDown ()

-- Converting from a replica set to standalone; on the primary:
rs.remove ("localhost:27001")
rs.remove ("localhost:27003")
-- Then shutdown the mongod instance and start again without --replSet parameter

-- How do you reverse the effect of rs.slaveOk ()?
-- How do you convert a replica set to a standalone? Even after removing all other members, when I start mongod, I get the error:
-- "mongod started without --replSet yet 1 documents are present in local.system.replset
-- Restart with --replSet unless you are doing maintenance and no other clients are connected.
-- The TTL collection monitor will not start because of this.
-- For more info see http://dochub.mongodb.org/core/ttlcollections

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Converting an existing standalone to a replica set
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

-- create folders c:\data\rs2\rs2.1, c:\data\rs2\rs2.2, c:\data\rs2\rs2.3 
-- To be on the safe side, we'll copy an existing standalone database (c:\data\db) to c:\data\rs2\rs2.1


+++++++++++++++++++++++
+ Replica Set, on three physical machines
+++++++++++++++++++++++

-- machine 1, 172.16.11.19
-- machine 2, 172.16.11.250
-- machine 3, 172.16.11.244
-- client machine, 172.16.11.25

-- machine 1
mongod --replSet rs1 

-- machine 2
mongod --replSet rs1 

-- machine 3
mongod --replSet rs1 

-- client machine
mongo 172.16.11.19

rsconfig = {_id: 'rs1', members: [
	{_id: 0, host: '172.16.11.19'},
	{_id: 1, host: '172.16.11.250'}
] }

rs.initiate (rsconfig)
rs.conf()
rs.status()
rs.add ('172.16.11.244')
rs.status()


-----------------------------------------
- GridFS
-----------------------------------------

db.videos.files.find().pretty()
db.videos.chunks.find( {}, {data:0})

------------------------------------------
- Geospatial indexes
------------------------------------------

db.zips.count()
db.zips.ensureIndex ( {loc: '2d'} )
db.zips.ensureIndex ( {loc: '2d', state: 1} )
db.zips.find ( {loc: {$near: [-72.622739, 42.070206] } } )
db.zips.find ( {loc: {$near: [-72.622739, 42.070206] } } ).limit(10)

db.zips.dropIndex ( {loc: '2d'} )
db.zips.dropIndex ( {loc: '2d', state: 1} )
db.zips.ensureIndex ( {loc: '2dsphere'} )
db.zips.find ( {loc: {$near: {
	$geometry: {
		type: 'Point',
		coordinates: [-87.635915, 41.878876]
}, $maxDistance: 100000} } } )

db.stores.find( {loc: {$near: {
    $geometry: {type: "Point", coordinates: [-130, 39] }, $maxDistance: 1000000
} } } )

-------------------------------
- Text indexes and search
-------------------------------

db.idioms.drop()
db.idioms.insert ( {
	idiom: "A Bird In The Hand Is Worth Two In The Bush ",
	meaning: "Having something that is certain is much better than taking a risk for more, because chances are you might lose everything. "
} )


db.idioms.insert ( {
	idiom: "A Blessing In Disguise ",
	meaning: "Something good that isn't recognized at first. "
} )


db.idioms.insert ( {
	idiom: "A Chip On Your Shoulder ",
	meaning: "Being upset for something that happened in the past. "
} )


db.idioms.insert ( {
	idiom: "A Dime A Dozen",
	meaning: "Anything that is common and easy to get. "
} )


db.idioms.insert ( {
	idiom: "A Doubting Thomas ",
	meaning: "A skeptic who needs physical or personal evidence in order to believe something. "
} )


db.idioms.insert ( {
	idiom: "A Drop in the Bucket ",
	meaning: "A very small part of something big or whole. "
} )


db.idioms.insert ( {
	idiom: "A Fool And His Money Are Easily Parted ",
	meaning: "It's easy for a foolish person to lose his/her money. "
} )


db.idioms.insert ( {
	idiom: "A House Divided Against Itself Cannot Stand ",
	meaning: "Everyone involved must unify and function together or it will not work out. "
} )


db.idioms.insert ( {
	idiom: "A Leopard Can't Change His Spots ",
	meaning: "You cannot change who you are. "
} )


db.idioms.insert ( {
	idiom: "A Penny Saved Is A Penny Earned ",
	meaning: "By not spending money, you are saving money (little by little). "
} )


db.idioms.insert ( {
	idiom: "A Picture Paints a Thousand Words ",
	meaning: "A visual presentation is far more descriptive than words. "
} )


db.idioms.insert ( {
	idiom: "A Piece of Cake ",
	meaning: "A task that can be accomplished very easily. "
} )


db.idioms.insert ( {
	idiom: "A Slap on the Wrist ",
	meaning: "A very mild punishment. "
} )


db.idioms.insert ( {
	idiom: "A Taste Of Your Own Medicine ",
	meaning: "When you are mistreated the same way you mistreat others. "
} )


db.idioms.insert ( {
	idiom: "A Toss-Up ",
	meaning: "A result that is still unclear and can go either way. "
} )


db.idioms.insert ( {
	idiom: "Actions Speak Louder Than Words ",
	meaning: "It's better to actually do something than just talk about it. "
} )


db.idioms.insert ( {
	idiom: "Add Fuel To The Fire ",
	meaning: "Whenever something is done to make a bad situation even worse than it is. "
} )


db.idioms.insert ( {
	idiom: "Against The Clock ",
	meaning: "Rushed and short on time. "
} )


db.idioms.insert ( {
	idiom: "All Bark And No Bite ",
	meaning: "When someone is threatening and/or aggressive but not willing to engage in a fight. "
} )


db.idioms.insert ( {
	idiom: "All Greek to me ",
	meaning: "Meaningless and incomprehensible like someone who cannot read, speak, or understand any of the Greek language would be. "
} )


db.idioms.insert ( {
	idiom: "All In The Same Boat ",
	meaning: "When everyone is facing the same challenges. "
} )


db.idioms.insert ( {
	idiom: "An Arm And A Leg ",
	meaning: "Very expensive. A large amount of money. "
} )


db.idioms.insert ( {
	idiom: "An Axe To Grind ",
	meaning: "To have a dispute with someone. "
} )


db.idioms.insert ( {
	idiom: "Apple of My Eye ",
	meaning: "Someone who is cherished above all others. "
} )


db.idioms.insert ( {
	idiom: "As High As A Kite ",
	meaning: "Anything that is high up in the sky. "
} )


db.idioms.insert ( {
	idiom: "At The Drop Of A Hat ",
	meaning: "Willing to do something immediately. "
} )


db.idioms.insert ( {
	idiom: "Back Seat Driver ",
	meaning: "People who criticize from the sidelines, much like someone giving unwanted advice from the back seat of a vehicle to the driver. "
} )


db.idioms.insert ( {
	idiom: "Back To Square One ",
	meaning: "Having to start all over again. "
} )


db.idioms.insert ( {
	idiom: "Back To The Drawing Board ",
	meaning: "When an attempt fails and it's time to start all over. "
} )


db.idioms.insert ( {
	idiom: "Baker's Dozen ",
	meaning: "Thirteen. "
} )


db.idioms.insert ( {
	idiom: "Barking Up The Wrong Tree ",
	meaning: "A mistake made in something you are trying to achieve. "
} )


db.idioms.insert ( {
	idiom: "Beat A Dead Horse ",
	meaning: "To force an issue that has already ended. "
} )


db.idioms.insert ( {
	idiom: "Beating Around The Bush ",
	meaning: "Avoiding the main topic. Not speaking directly about the issue. "
} )


db.idioms.insert ( {
	idiom: "Bend Over Backwards ",
	meaning: "Do whatever it takes to help. Willing to do anything. "
} )


db.idioms.insert ( {
	idiom: "Between A Rock And A Hard Place ",
	meaning: "Stuck between two very bad options. "
} )


db.idioms.insert ( {
	idiom: "Bite Off More Than You Can Chew ",
	meaning: "To take on a task that is way to big. "
} )


db.idioms.insert ( {
	idiom: "Bite Your Tongue ",
	meaning: "To avoid talking. "
} )


db.idioms.insert ( {
	idiom: "Blood Is Thicker Than Water ",
	meaning: "The family bond is closer than anything else. "
} )


db.idioms.insert ( {
	idiom: "Blue Moon ",
	meaning: "A rare event or occurance. "
} )


db.idioms.insert ( {
	idiom: "Break A Leg ",
	meaning: "A superstitious way to say 'good luck' without saying 'good luck', but rather the opposite. "
} )


db.idioms.insert ( {
	idiom: "Buy A Lemon ",
	meaning: "To purchase a vehicle that constantly gives problems or stops running after you drive it away. "
} )




db.idioms.insert ( {
	idiom: "Can't Cut The Mustard  ",
	meaning: "Someone who isn't adequate enough to compete or participate. "
} )


db.idioms.insert ( {
	idiom: "Cast Iron Stomach ",
	meaning: "Someone who has no problems, complications or ill effects with eating anything or drinking anything. "
} )


db.idioms.insert ( {
	idiom: "Charley Horse ",
	meaning: "Stiffness in the leg / A leg cramp. "
} )


db.idioms.insert ( {
	idiom: "Chew someone out ",
	meaning: "Verbally scold someone. "
} )


db.idioms.insert ( {
	idiom: "Chip on his Shoulder ",
	meaning: "Angry today about something that occured in the past. "
} )


db.idioms.insert ( {
	idiom: "Chow Down ",
	meaning: "To eat. "
} )


db.idioms.insert ( {
	idiom: "Close but no Cigar ",
	meaning: "To be very near and almost accomplish a goal, but fall short. "
} )


db.idioms.insert ( {
	idiom: "Cock and Bull Story ",
	meaning: "An unbelievable tale. "
} )


db.idioms.insert ( {
	idiom: "Come Hell Or High Water ",
	meaning: "Any difficult situation or obstacle. "
} )


db.idioms.insert ( {
	idiom: "Crack Someone Up ",
	meaning: "To make someone laugh. "
} )


db.idioms.insert ( {
	idiom: "Cross Your Fingers ",
	meaning: "To hope that something happens the way you want it to. "
} )


db.idioms.insert ( {
	idiom: "Cry Over Spilt Milk ",
	meaning: "When you complain about a loss from the past. "
} )


db.idioms.insert ( {
	idiom: "Cry Wolf ",
	meaning: "Intentionally raise a false alarm. "
} )


db.idioms.insert ( {
	idiom: "Cup Of Joe ",
	meaning: "A cup of coffee. "
} )


db.idioms.insert ( {
	idiom: "Curiosity Killed The Cat ",
	meaning: "Being Inquisitive can lead you into a dangerous situation. "
} )


db.idioms.insert ( {
	idiom: "Cut to the Chase ",
	meaning: "Leave out all the unnecessary details and just get to the point. "
} )






db.idioms.insert ( {
	idiom: "Dark Horse ",
	meaning: "One who was previously unknown and is now prominent. "
} )


db.idioms.insert ( {
	idiom: "Dead Ringer ",
	meaning: "100% identical. A duplicate. "
} )


db.idioms.insert ( {
	idiom: "Devil's Advocate ",
	meaning: "Someone who takes a position for the sake of argument without believing in that particular side of the arguement. It can also mean one who presents a counter argument for a position they do believe in, to another debater. "
} )


db.idioms.insert ( {
	idiom: "Dog Days of Summer ",
	meaning: "The hottest days of the summer season. "
} )


db.idioms.insert ( {
	idiom: "Don't count your chickens before they hatch ",
	meaning: "Don't rely on it until your sure of it. "
} )


db.idioms.insert ( {
	idiom: "Don't Look A Gift Horse In The Mouth ",
	meaning: "When someone gives you a gift, don't be ungrateful. "
} )


db.idioms.insert ( {
	idiom: "Don't Put All Your Eggs In One Basket ",
	meaning: "Do not put all your resources in one possibility. "
} )


db.idioms.insert ( {
	idiom: "Doozy ",
	meaning: "Something outstanding. "
} )


db.idioms.insert ( {
	idiom: "Down To The Wire ",
	meaning: "Something that ends at the last minute or last few seconds. "
} )


db.idioms.insert ( {
	idiom: "Drastic Times Call For Drastic Measures ",
	meaning: "When you are extremely desperate you need to take extremely desperate actions. "
} )


db.idioms.insert ( {
	idiom: "Drink like a fish ",
	meaning: "To drink very heavily. "
} )


db.idioms.insert ( {
	idiom: "Drive someone up the wall ",
	meaning: "To irritate and/or annoy very much. "
} )


db.idioms.insert ( {
	idiom: "Dropping Like Flies ",
	meaning: "A large number of people either falling ill or dying. "
} )


db.idioms.insert ( {
	idiom: "Dry Run ",
	meaning: "Rehearsal. "
} )
db.idioms.insert ( {
	idiom: "Eighty Six ",
	meaning: "A certain item is no longer available. Or this idiom can also mean, to throw away. "
} )



db.idioms.insert ( {
	idiom: "Elvis has left the building ",
	meaning: "The show has come to an end. It's all over. "
} )



db.idioms.insert ( {
	idiom: "Ethnic Cleansing ",
	meaning: "Killing of a certain ethnic or religious group on a massive scale. "
} )



db.idioms.insert ( {
	idiom: "Every Cloud Has A Silver Lining ",
	meaning: "Be optomistic, even difficult times will lead to better days. "
} )



db.idioms.insert ( {
	idiom: "Everything But The Kitchen Sink ",
	meaning: "Almost everything and anything has been included. "
} )



db.idioms.insert ( {
	idiom: "Excuse my French ",
	meaning: "Please forgive me for cussing. "
} )


db.idioms.insert ( {
	idiom: "Cock and Bull Story ",
	meaning: "An unbelievable tale. "
} )


db.idioms.insert ( {
	idiom: "Cock and Bull Story ",
	meaning: "An unbelievable tale. "
} )



db.idioms.insert ( {
	idiom: "Feeding Frenzy ",
	meaning: "An aggressive attack on someone by a group. "
} )


db.idioms.insert ( {
	idiom: "Field Day ",
	meaning: "An enjoyable day or circumstance. "
} )


db.idioms.insert ( {
	idiom: "Finding Your Feet ",
	meaning: "To become more comfortable in whatever you are doing. "
} )


db.idioms.insert ( {
	idiom: "Finger lickin' good ",
	meaning: "A very tasty food or meal. "
} )


db.idioms.insert ( {
	idiom: "Fixed In Your Ways ",
	meaning: "Not willing or wanting to change from your normal way of doing something. "
} )


db.idioms.insert ( {
	idiom: "Flash In The Pan ",
	meaning: "Something that shows potential or looks promising in the beginning but fails to deliver anything in the end. "
} )


db.idioms.insert ( {
	idiom: "Flea Market ",
	meaning: "A swap meet. A place where people gather to buy and sell inexpensive goods. "
} )


db.idioms.insert ( {
	idiom: "Flesh and Blood ",
	meaning: "This idiom can mean living material of which people are made of, or it can refer to someone's family. "
} )


db.idioms.insert ( {
	idiom: "Flip The Bird ",
	meaning: "To raise your middle finger at someone. "
} )


db.idioms.insert ( {
	idiom: "Foam at the Mouth ",
	meaning: "To be enraged and show it. "
} )


db.idioms.insert ( {
	idiom: "Fools' Gold ",
	meaning: "Iron pyrites, a worthless rock that resembles real gold. "
} )


db.idioms.insert ( {
	idiom: "French Kiss ",
	meaning: "An open mouth kiss where tongues touch. "
} )


db.idioms.insert ( {
	idiom: "From Rags To Riches ",
	meaning: "To go from being very poor to being very wealthy. "
} )


db.idioms.insert ( {
	idiom: "Fuddy-duddy ",
	meaning: "An old-fashioned and foolish type of person. "
} )


db.idioms.insert ( {
	idiom: "Full Monty ",
	meaning: "This idiom can mean either, "the whole thing" or "completely nude"."
} )


db.idioms.insert ( {
	idiom: "Funny Farm ",
	meaning: "A mental institutional facility. "
} )



db.idioms.insert ( {
	idiom: "Get Down to Brass Tacks ",
	meaning: "To become serious about something. "
} )


db.idioms.insert ( {
	idiom: "Get Over It ",
	meaning: "To move beyond something that is bothering you. "
} )


db.idioms.insert ( {
	idiom: "Get Up On The Wrong Side Of The Bed ",
	meaning: "Someone who is having a horrible day. "
} )


db.idioms.insert ( {
	idiom: "Get Your Walking Papers ",
	meaning: "Get fired from a job. "
} )


db.idioms.insert ( {
	idiom: "Give Him The Slip ",
	meaning: "To get away from. To escape. "
} )


db.idioms.insert ( {
	idiom: "Go Down Like A Lead Balloon ",
	meaning: "To be received badly by an audience. "
} )


db.idioms.insert ( {
	idiom: "Go For Broke ",
	meaning: "To gamble everything you have. "
} )


db.idioms.insert ( {
	idiom: "Go Out On A Limb ",
	meaning: "Put yourself in a tough position in order to support someone/something. "
} )


db.idioms.insert ( {
	idiom: "Go The Extra Mile ",
	meaning: "Going above and beyond whatever is required for the task at hand. "
} )


db.idioms.insert ( {
	idiom: "Good Samaritan ",
	meaning: "Someone who helps others when they are in need, with no discussion for compensation, and no thought of a reward. "
} )


db.idioms.insert ( {
	idiom: "Graveyard Shift ",
	meaning: "Working hours from about 1200 am to 800 am. The time of the day when most other people are sleeping. "
} )


db.idioms.insert ( {
	idiom: "Great Minds Think Alike ",
	meaning: "Intelligent people think like each other. "
} )


db.idioms.insert ( {
	idiom: "Green Room ",
	meaning: "The waiting room, especially for those who are about to go on a tv or radio show. "
} )


db.idioms.insert ( {
	idiom: "Gut Feeling ",
	meaning: "A personal intuition you get, especially when feel something may not be right. "
} )




db.idioms.insert ( {
	idiom: "Haste Makes Waste ",
	meaning: "Quickly doing things results in a poor ending. "
} )


db.idioms.insert ( {
	idiom: "Hat Trick ",
	meaning: "When one player scores three goals in the same hockey game. This idiom can also mean three scores in any other sport, such as 3 homeruns, 3 touchdowns, 3 soccer goals, etc. "
} )


db.idioms.insert ( {
	idiom: "Have an Axe to Grind ",
	meaning: "To have a dispute with someone. "
} )


db.idioms.insert ( {
	idiom: "He Lost His Head ",
	meaning: "Angry and overcome by emotions. "
} )


db.idioms.insert ( {
	idiom: "Head Over Heels ",
	meaning: "Very excited and/or joyful, especially when in love. "
} )


db.idioms.insert ( {
	idiom: "Hell in a Handbasket ",
	meaning: "Deteriorating and headed for complete disaster. "
} )


db.idioms.insert ( {
	idiom: "High Five ",
	meaning: "Slapping palms above each others heads as celebration gesture. "
} )


db.idioms.insert ( {
	idiom: "High on the Hog ",
	meaning: "Living in Luxury. "
} )


db.idioms.insert ( {
	idiom: "Hit The Books ",
	meaning: "To study, especially for a test or exam. "
} )


db.idioms.insert ( {
	idiom: "Hit The Hay ",
	meaning: "Go to bed or go to sleep. "
} )


db.idioms.insert ( {
	idiom: "Hit The Nail on the Head ",
	meaning: "Do something exactly right or say something exactly right. "
} )


db.idioms.insert ( {
	idiom: "Hit The Sack ",
	meaning: "Go to bed or go to sleep. "
} )


db.idioms.insert ( {
	idiom: "Hocus Pocus ",
	meaning: "In general, a term used in magic or trickery. "
} )


db.idioms.insert ( {
	idiom: "Hold Your Horses ",
	meaning: "Be patient. "
} )



db.idioms.insert ( {
	idiom: "Icing On The Cake ",
	meaning: "When you already have it good and get something on top of what you already have. "
} )


db.idioms.insert ( {
	idiom: "Idle Hands Are The Devil's Tools ",
	meaning: "You are more likely to get in trouble if you have nothing to do. "
} )


db.idioms.insert ( {
	idiom: "If It's Not One Thing, It's Another ",
	meaning: "When one thing goes wrong, then another, and another... "
} )


db.idioms.insert ( {
	idiom: "In Like Flynn ",
	meaning: "To be easily successful, especially when sexual or romantic. "
} )


db.idioms.insert ( {
	idiom: "In The Bag ",
	meaning: "To have something secured. "
} )


db.idioms.insert ( {
	idiom: "In The Buff ",
	meaning: "Nude. "
} )


db.idioms.insert ( {
	idiom: "In The Heat Of The Moment ",
	meaning: "Overwhelmed by what is happening in the moment. "
} )


db.idioms.insert ( {
	idiom: "In Your Face ",
	meaning: "An aggressive and bold confrontation. "
} )


db.idioms.insert ( {
	idiom: "It Takes Two To Tango ",
	meaning: "A two person conflict where both people are at fault. "
} )


db.idioms.insert ( {
	idiom: "It's A Small World ",
	meaning: "You frequently see the same people in different places. "
} )


db.idioms.insert ( {
	idiom: "Its Anyone's Call ",
	meaning: "A competition where the outcome is difficult to judge or predict. "
} )


db.idioms.insert ( {
	idiom: "Ivy League ",
	meaning: "Since 1954 the Ivy League has been the following universities Columbia, Brown, Cornell, Dartmouth, Yale, Pennsylvania, Princeton, and Harvard. "
} )


db.idioms.insert ( {
	idiom: "Jaywalk ",
	meaning: "Crossing the street (from the middle) without using the crosswalk. "
} )


db.idioms.insert ( {
	idiom: "Joshing Me ",
	meaning: "Tricking me. "
} )



db.idioms.insert ( {
	idiom: "Keep An Eye On Him ",
	meaning: "You should carefully watch him. "
} )


db.idioms.insert ( {
	idiom: "Keep body and soul together ",
	meaning: "To earn a sufficient amount of money in order to keep yourself alive . "
} )


db.idioms.insert ( {
	idiom: "Keep your chin up ",
	meaning: "To remain joyful in a tough situation. "
} )


db.idioms.insert ( {
	idiom: "Kick The Bucket ",
	meaning: "Die. "
} )


db.idioms.insert ( {
	idiom: "Kitty-corner ",
	meaning: "Diagonally across. Sometimes called Catty-Corner as well. "
} )


db.idioms.insert ( {
	idiom: "Knee Jerk Reaction ",
	meaning: "A quick and automatic response. "
} )


db.idioms.insert ( {
	idiom: "Knock On Wood ",
	meaning: "Knuckle tapping on wood in order to avoid some bad luck. "
} )


db.idioms.insert ( {
	idiom: "Know the Ropes ",
	meaning: "To understand the details. "
} )




db.idioms.insert ( {
	idiom: "Last but not least ",
	meaning: "An introduction phrase to let the audience know that the last person mentioned is no less important than those introduced before him/her. "
} )


db.idioms.insert ( {
	idiom: "Lend Me Your Ear ",
	meaning: "To politely ask for someone's full attention. "
} )


db.idioms.insert ( {
	idiom: "Let Bygones Be Bygones ",
	meaning: "To forget about a disagreement or arguement. "
} )


db.idioms.insert ( {
	idiom: "Let Sleeping Dogs Lie ",
	meaning: "To avoid restarting a conflict. "
} )


db.idioms.insert ( {
	idiom: "Let The Cat Out Of The Bag ",
	meaning: "To share a secret that wasn't suppose to be shared. "
} )


db.idioms.insert ( {
	idiom: "Level playing field ",
	meaning: "A fair competition where no side has an advantage. "
} )


db.idioms.insert ( {
	idiom: "Like a chicken with its head cut off ",
	meaning: "To act in a frenzied manner. "
} )


db.idioms.insert ( {
	idiom: "liquor someone up ",
	meaning: "To get someone drunk. "
} )


db.idioms.insert ( {
	idiom: "Long in the Tooth ",
	meaning: "Old people (or horses). "
} )


db.idioms.insert ( {
	idiom: "Loose Cannon ",
	meaning: "Someone who is unpredictable and can cause damage if not kept in check. "
} )




db.idioms.insert ( {
	idiom: "Make No Bones About ",
	meaning: "To state a fact so there are no doubts or objections. "
} )


db.idioms.insert ( {
	idiom: "Method To My Madness ",
	meaning: "Strange or crazy actions that appear meaningless but in the end are done for a good reason. "
} )


db.idioms.insert ( {
	idiom: "Mumbo Jumbo ",
	meaning: "Nonsense or meaningless speech. "
} )


db.idioms.insert ( {
	idiom: "Mum's the word ",
	meaning: "To keep quiet. To say nothing. "
} )



db.idioms.insert ( {
	idiom: "Nest Egg ",
	meaning: "Savings set aside for future use. "
} )


db.idioms.insert ( {
	idiom: "Never Bite The Hand That Feeds You ",
	meaning: "Don't hurt anyone that helps you. "
} )


db.idioms.insert ( {
	idiom: "New kid on the block ",
	meaning: "Someone new to the group or area. "
} )


db.idioms.insert ( {
	idiom: "New York Minute ",
	meaning: "A minute that seems to go by quickly, especially in a fast paced environment. "
} )


db.idioms.insert ( {
	idiom: "No Dice ",
	meaning: "To not agree. To not accept a proposition. "
} )


db.idioms.insert ( {
	idiom: "No Room to Swing a Cat ",
	meaning: "An unsually small or confined space. "
} )


db.idioms.insert ( {
	idiom: "Not Playing With a Full Deck ",
	meaning: "Someone who lacks intelligence. "
} )



db.idioms.insert ( {
	idiom: "Off On The Wrong Foot ",
	meaning: "Getting a bad start on a relationship or task. "
} )


db.idioms.insert ( {
	idiom: "Off The Hook ",
	meaning: "No longer have to deal with a tough situation. "
} )


db.idioms.insert ( {
	idiom: "Off the Record ",
	meaning: "Something said in confidence that the one speaking doesn't want attributed to him/her. "
} )


db.idioms.insert ( {
	idiom: "On Pins And Needles ",
	meaning: "Anxious or nervous, especially in anticipation of something. "
} )


db.idioms.insert ( {
	idiom: "On The Fence ",
	meaning: "Undecided. "
} )


db.idioms.insert ( {
	idiom: "On The Same Page ",
	meaning: "When multiple people all agree on the same thing. "
} )


db.idioms.insert ( {
	idiom: "Out Of The Blue ",
	meaning: "Something that suddenly and unexpectedly occurs. "
} )


db.idioms.insert ( {
	idiom: "Out On A Limb ",
	meaning: "When someone puts themself in a risky situation. "
} )


db.idioms.insert ( {
	idiom: "Out On The Town ",
	meaning: "To enjoy yourself by going out. "
} )


db.idioms.insert ( {
	idiom: "Over My Dead Body ",
	meaning: "When you absolutely will not allow something to happen. "
} )


db.idioms.insert ( {
	idiom: "Over the Top ",
	meaning: "Very excessive. "
} )



db.idioms.insert ( {
	idiom: "Pass The Buck ",
	meaning: "Avoid responsibility by giving it to someone else. "
} )


db.idioms.insert ( {
	idiom: "Pedal to the metal ",
	meaning: "To go full speed, especially while driving a vehicle. "
} )


db.idioms.insert ( {
	idiom: "Peeping Tom ",
	meaning: "Someone who observes people in the nude or sexually active people, mainly for his own gratification. "
} )


db.idioms.insert ( {
	idiom: "Pick up your ears ",
	meaning: "To listen very carefully. "
} )


db.idioms.insert ( {
	idiom: "Pig In A Poke ",
	meaning: "A deal that is made without first examining it. "
} )


db.idioms.insert ( {
	idiom: "Pig Out  ",
	meaning: "To eat alot and eat it quickly. "
} )


db.idioms.insert ( {
	idiom: "Pipe Down ",
	meaning: "To shut-up or be quiet. "
} )


db.idioms.insert ( {
	idiom: "Practice Makes Perfect ",
	meaning: "By constantly practicing, you will become better. "
} )


db.idioms.insert ( {
	idiom: "Pull the plug ",
	meaning: "To stop something. To bring something to an end. "
} )


db.idioms.insert ( {
	idiom: "Pulling Your Leg ",
	meaning: "Tricking someone as a joke. "
} )


db.idioms.insert ( {
	idiom: "Put a sock in it ",
	meaning: "To tell noisy person or a group to be quiet. "
} )



db.idioms.insert ( {
	idiom: "Queer the pitch ",
	meaning: "Destroy or ruin a plan. "
} )



db.idioms.insert ( {
	idiom: "Raincheck ",
	meaning: "An offer or deal that is declined right now but willing to accept later. "
} )


db.idioms.insert ( {
	idiom: "Raining Cats and Dogs ",
	meaning: "A very loud and noisy rain storm. "
} )


db.idioms.insert ( {
	idiom: "Ring Fencing ",
	meaning: "Seperated usual judgement to guarantee protection, especially project funds. "
} )


db.idioms.insert ( {
	idiom: "Rise and Shine ",
	meaning: "Time to get out of bed and get ready for work/school. "
} )


db.idioms.insert ( {
	idiom: "Rome Was Not Built In One Day ",
	meaning: "If you want something to be completely properly, then its going to take time. "
} )


db.idioms.insert ( {
	idiom: "Rule Of Thumb ",
	meaning: "A rough estimate. "
} )


db.idioms.insert ( {
	idiom: "Run out of steam ",
	meaning: "To be completely out of energy. "
} )



db.idioms.insert ( {
	idiom: "Saved By The Bell ",
	meaning: "Saved at the last possible moment. "
} )


db.idioms.insert ( {
	idiom: "Scapegoat ",
	meaning: "Someone else who takes the blame. "
} )


db.idioms.insert ( {
	idiom: "Scot-free ",
	meaning: "To escape and not have to pay. "
} )


db.idioms.insert ( {
	idiom: "Sick As A Dog ",
	meaning: "To be very sick (with the flu or a cold). "
} )


db.idioms.insert ( {
	idiom: "Sitting Shotgun ",
	meaning: "Riding in the front passenger seat of a car. "
} )


db.idioms.insert ( {
	idiom: "Sixth Sense ",
	meaning: "A paranormal sense that allows you to communicate with the dead. "
} )


db.idioms.insert ( {
	idiom: "Skid Row ",
	meaning: "The rundown area of a city where the homeless and drug users live. "
} )


db.idioms.insert ( {
	idiom: "Smell A Rat ",
	meaning: "To detect somone in the group is betraying the others. "
} )


db.idioms.insert ( {
	idiom: "Smell Something Fishy ",
	meaning: "Detecting that something isn't right and there might be a reason for it. "
} )


db.idioms.insert ( {
	idiom: "Son of a Gun ",
	meaning: "A scamp. "
} )


db.idioms.insert ( {
	idiom: "Southpaw ",
	meaning: "Someone who is left-handed. "
} )


db.idioms.insert ( {
	idiom: "Spitting Image ",
	meaning: "The exact likeness or kind. "
} )


db.idioms.insert ( {
	idiom: "Start From Scratch ",
	meaning: "To do it all over again from the beginning. "
} )



db.idioms.insert ( {
	idiom: "The Ball Is In Your Court ",
	meaning: "It is your decision this time. "
} )


db.idioms.insert ( {
	idiom: "The Best Of Both Worlds ",
	meaning: "There are two choices and you have them both. "
} )


db.idioms.insert ( {
	idiom: "The Bigger They Are The Harder They Fall ",
	meaning: "While the bigger and stronger opponent might be alot more difficult to beat, when you do they suffer a much bigger loss. "
} )


db.idioms.insert ( {
	idiom: "The Last Straw ",
	meaning: "When one small burden after another creates an unbearable situation, the last straw is the last small burden that one can take. "
} )


db.idioms.insert ( {
	idiom: "The Whole Nine Yards ",
	meaning: "Everything. All of it. "
} )


db.idioms.insert ( {
	idiom: "Third times a charm ",
	meaning: "After no success the first two times, the third try is a lucky one. "
} )


db.idioms.insert ( {
	idiom: "Tie the knot ",
	meaning: "To get married. "
} )


db.idioms.insert ( {
	idiom: "Til the cows come home ",
	meaning: "A long time. "
} )


db.idioms.insert ( {
	idiom: "To Make A Long Story Short ",
	meaning: "Something someone would say during a long and boring story in order to keep his/her audience from losing attention. Usually the story isn't shortened. "
} )


db.idioms.insert ( {
	idiom: "To Steal Someone's Thunder ",
	meaning: "To take the credit for something someone else did. "
} )


db.idioms.insert ( {
	idiom: "Tongue-in-cheek ",
	meaning: "humor, not to be taken serious. "
} )


db.idioms.insert ( {
	idiom: "Turn A Blind Eye ",
	meaning: "Refuse to acknowledge something you know is real or legit. "
} )


db.idioms.insert ( {
	idiom: "Twenty three skidoo ",
	meaning: "To be turned away. "
} )



db.idioms.insert ( {
	idiom: "Under the weather ",
	meaning: "Feeling ill or sick. "
} )


db.idioms.insert ( {
	idiom: "Up a blind alley ",
	meaning: "Going down a course of action that leads to a bad outcome. "
} )


db.idioms.insert ( {
	idiom: "Use Your Loaf ",
	meaning: "Use your head. Think smart. "
} )



db.idioms.insert ( {
	idiom: "Van Gogh's ear for music ",
	meaning: "Tone deaf. "
} )


db.idioms.insert ( {
	idiom: "Variety Is The Spice Of Life ",
	meaning: "The more experiences you try the more exciting life can be. "
} )



db.idioms.insert ( {
	idiom: "Wag the Dog ",
	meaning: "A diversion away from something of greater importance. "
} )


db.idioms.insert ( {
	idiom: "Water Under The Bridge ",
	meaning: "Anything from the past that isn't significant or important anymore. "
} )


db.idioms.insert ( {
	idiom: "Wear Your Heart On Your Sleeve ",
	meaning: "To openly and freely express your emotions. "
} )


db.idioms.insert ( {
	idiom: "When It Rains, It Pours ",
	meaning: "Since it rarely rains, when it does it will be a huge storm. "
} )


db.idioms.insert ( {
	idiom: "When Pigs Fly  ",
	meaning: "Something that will never ever happen. "
} )


db.idioms.insert ( {
	idiom: "Wild and Woolly ",
	meaning: "Uncultured and without laws. "
} )


db.idioms.insert ( {
	idiom: "Wine and Dine ",
	meaning: "When somebody is treated to an expensive meal. "
} )


db.idioms.insert ( {
	idiom: "Without A Doubt ",
	meaning: "For certain. "
} )


db.idioms.insert ( {
	idiom: "X marks the spot ",
	meaning: "A phrase that is said when someone finds something he/she has been looking for. "
} )





db.idioms.insert ( {
	idiom: "You Are What You Eat ",
	meaning: "In order to stay healthy you must eat healthy foods. "
} )


db.idioms.insert ( {
	idiom: "You Can't Judge A Book By Its Cover ",
	meaning: "Decisions shouldn't be made primarily on appearance. "
} )


db.idioms.insert ( {
	idiom: "You Can't Take it With You ",
	meaning: "Enjoy what you have and not what you don't have, since when you die you cannot take things (such as money) with you. "
} )


db.idioms.insert ( {
	idiom: "Your Guess Is As Good As Mine ",
	meaning: "I have no idea. "
} )


db.idioms.insert ( {
	idiom: "Zero Tolerance",
	meaning: "No crime or law breaking big or small will be overlooked. "
} )

db.idioms.count()

db.idioms.ensureIndex ( {idiom: 'text'} )
db.idioms.find ( {$text: {$search: 'book'} } )
db.idioms.find ( {$text: {$search: 'book cover'} } )
db.idioms.find ( {$text: {$search: 'cat'} } )
db.idioms.find ( {$text: {$search: 'cat water'} } )

-- Following will give error; you can have only one index of type 'text' for a collection.
db.idioms.ensureIndex ( {meaning: 'text'} )

-- But you can do the following:
db.idioms.getIndexes()
db.idioms.dropIndex ("idiom_text")
db.idioms.ensureIndex ( {idiom: 'text', meaning: 'text'} )
db.idioms.find ( {$text: {$search: 'book crime'} } )

-- Also
db.idioms.getIndexes()
db.idioms.dropIndex ("idiom_text_meaning_text")
db.idioms.ensureIndex ( {'$**': 'text'}, {name: 'FullTextIndex'} )

db.idioms.find ( {$text: {$search: 'book crime'} }, {score: {$meta: 'textScore'} } ).sort ( {score: {$meta: 'textScore'} } )

-- Assigning weights

db.idioms.dropIndex ('FullTextIndex')
db.idioms.ensureIndex ( 
	{idiom: 'text', meaning: 'text'},
	{weights: {idiom: 5, meaning: 1}},
	{name: 'TextIndex'}
)


year
student_id
physics
chemistry
maths

year 2010: 0974195 students
year 2011: 0984222 students
year 2012: 1105429 students
year 2013: 1407822 students

for each of the above years
	for students_id from 1 to number of students
		for each of the three subjects
			generate two random numbers between 0 and 100 and take their average as the marks of the student

{year: 2010, student_id: 1, physics: 60, chemistry: 65, maths: 70}

----------------------------------
- Aggregation framework
----------------------------------

-- All ZIPs with population >= 10000
db.zips.find( {pop: {$gte: 10000}}).pretty()

-- State-wise count of ZIP codes
db.zips.aggregate ( 
	{$group: {_id: '$state', zip_count: {$sum: 1}}}
).pretty()

-- Or
db.zips.aggregate (
	{$group: {_id: {state: '$state'}, zip_count: {$sum: 1}}}
).pretty()

-- Sort the above in descending order of zip_count
db.zips.aggregate ( 
	{$group: 
		{_id: '$state', zip_count: {$sum: 1}}},
	{$sort: {zip_count: -1}}
).pretty()

-- Sort the above in ascending order of state code
db.zips.aggregate ( 
	{$group: 
		{_id: '$state', zip_count: {$sum: 1}}},
	{$sort: {_id: 1}}
).pretty()

-- Compound grouping
db.zips.aggregate (
	{$group: {_id: {city: '$city', state: '$state'}, zip_count: {$sum: 1}}}
).pretty()

-- State-wise sum of population
db.zips.aggregate (
	{$group: {_id: '$state', population: {$sum: '$pop'}}}
).pretty()

-- Sort the above in descending order of population
db.zips.aggregate (
	{$group: {_id: '$state', population: {$sum: '$pop'}}},
	{$sort: {population: -1}}
).pretty()

-- Sort the above in ascending order of state code
db.zips.aggregate (
	{$group: {_id: '$state', population: {$sum: '$pop'}}},
	{$sort: {_id: 1}}
).pretty()

-- Restrict the above list to states with population of 10 million or more
db.zips.aggregate (
	{$group: {_id: '$state', population: {$sum: '$pop'}}},
	{$match: {population: {$gte: 10*1000*1000}}},
	{$sort: {_id: 1}}
).pretty()

-- One document per state, with list of its cities in an array inside it
db.zips.aggregate (
	{$group: {_id: '$state', cities: {$addToSet: '$city'}}}
).pretty()

-- For each state print the population of the zip code with the highest population in each state.
db.zips.aggregate (
	{$group: {_id: '$state', pop: {$max: '$pop'} } }
)

-- Also include the minimum population in the above result
db.zips.aggregate (
	{$group: {_id: '$state', max: {$max: '$pop'}, min: {$min: '$pop'} } }
)

-- Transform the data with city + state, zip, population fields
db.zips.aggregate (
	{$project: {_id: 0, city_state: {$concat: ['$city', ', ', '$state'] }, zip: '$_id', population: '$pop' } }
)

-- Same as above, but with city + state converted to lower case
db.zips.aggregate (
	{$project: {_id: 0, city_state: {$toLower: {$concat: ['$city', ', ', '$state'] } }, zip: '$_id', population: '$pop' } }
)

-- For the state of Florida, get city-wise population and list of zip codes
db.zips.aggregate (
	{$match: {state: 'FL'} },
	{$group: {_id: '$city', population: {$sum: '$pop'}, zips: {$addToSet: '$_id'} } }
)

-- Sort the above in descending order of population
db.zips.aggregate (
	{$match: {state: 'FL'} },
	{$group: {_id: '$city', population: {$sum: '$pop'}, zips: {$addToSet: '$_id'} } },
	{$sort: {population: -1} }
)

-- Just sorting by state name, city name (both ascending)
db.zips.aggregate (
	{$sort: {state: 1, city: 1} }
)

-- Skip and limit
db.zips.aggregate (
	{$sort: {state: 1, city: 1} },
	{$skip: 3},
	{$limit: 2}
)

-- State-wise list of the city with largest population
db.zips.aggregate (
	{$group: {_id: {state: '$state', city: '$city'}, population: {$sum: '$pop'} } },
	{$sort: {'_id.state': 1, population: -1} },
	{$group: {_id: {state: '$_id.state'}, city: {$first: '$_id.city'}, population: {$first: '$population'}} },
	{$sort: {population: -1} }
)

-- State-wise list of the biggest and smallest cities (by population)
db.zips.aggregate (
	{$group: {_id: {state: '$state', city: '$city'}, population: {$sum: '$pop'} } },
	{$sort: {'_id.state': 1, population: -1} },
	{$group: {
		_id: {state: '$_id.state'},
		largestcity: {$first: '$_id.city'},
		largestpopulation: {$first: '$population'},
		smallestcity: {$last: '$_id.city'},
		smallestpopulation: {$last: '$population'}
		} 
	},
	{$project: {
		_id: 0,
		state: '$_id.state',
		largest: {
			city: '$largestcity',
			population: '$largestpopulation'
		},
		smallest: {
			city: '$smallestcity',
			population: '$smallestpopulation'
		} } 
	},
	{$sort: {state: 1} }
)

-- Normalize the persons collection on languages
db.persons.aggregate (
	{$project: {_id: 0, name: {$concat: ['$name.first', ' ', '$name.last']}, languages: 1 } },
	{$unwind: '$languages'}
)

-- From persons collection extract {name, language, proficiency}, sorted by language name and person name

db.persons.aggregate (
	{$project: {_id: 0, name: {$concat: ['$name.first', ' ', '$name.last']}, languages: 1 } },
	{$unwind: '$languages'},
	{$sort: {'languages.name': 1, name: 1}},
	{$project: {language: '$languages.name', name: 1, proficiency: '$languages.proficiency'} }
)

-- Count the number of people at different proficiency levels in the above requirement
db.persons.aggregate (
	{$project: {_id: 0, name: {$concat: ['$name.first', ' ', '$name.last']}, languages: 1 } },
	{$unwind: '$languages'},
	{$sort: {'languages.name': 1, 'languages.proficiency': 1}},
	{$group: {_id: {language: '$languages.name', proficiency: '$languages.proficiency'}, count: {$sum: 1}}},
	{$project: {_id: 0, language: '$_id.language', proficiency: {level: '$_id.proficiency', count: '$count'}}},
	{$group: {_id: '$language', proficiency: {$addToSet: '$proficiency'} } }
)

----------------------------------
- Transactions with two-phase commit
----------------------------------

db.accounts.insert ( {customer: 'Pradyumn', balance: 1000, pendingTransactions: []})
db.accounts.insert ( {customer: 'Preeti', balance: 2000, pendingTransactions: []})
db.accounts.find()

db.transactions.insert ( {from: 'Pradyumn', to: 'Preeti', amount: 111, initiatedby: 'Thread1', state: 'initial'})
db.transactions.find()

t = db.transactions.findOne ( {state: 'initial', initiatedby: 'Thread1'})
db.transactions.update(
	{_id: t._id},
	{$set: {state: 'pending'}}
)
db.transactions.find()

db.accounts.update(
	{customer: t.from, pendingTransactions: {$ne: t._id}},
	{$inc: {balance: -t.amount}, $push: {pendingTransactions: t._id}}
)
db.accounts.update(
	{customer: t.to, pendingTransactions: {$ne: t._id}},
	{$inc: {balance: t.amount}, $push: {pendingTransactions: t._id}}
)
db.accounts.find()

db.transactions.update(
	{_id: t._id},
	{$set: {state: 'committed'}}
)
db.transactions.find()

db.accounts.update (
	{customer: t.from},
	{$pull: {pendingTransactions: t._id}}
)
db.accounts.update (
	{customer: t.to},
	{$pull: {pendingTransactions: t._id}}
)
db.accounts.find()

db.transactions.update (
	{_id: t._id},
	{$set: {state: 'done'}}
)
db.transactions.find()
	
----------------------------------
- Sharding, on one machine with different processes
----------------------------------

-- We’ll create two shards (shard1 and shard2)
-- each shard will have three servers in a replica set, with the following port numbers and data folders:
-- shard1a: 27021, c:\data\shard1\shard1a
-- shard1b: 27022 , c:\data\shard1\shard1b
-- shard1c: 27023 , c:\data\shard1\shard1c
-- shard2a: 27031 , c:\data\shard2\shard2a
-- shard2b: 27032 , c:\data\shard2\shard2b
-- shard2c: 27033 , c:\data\shard2\shard2c
-- We also need at least one (okay in development environment) or three (recommended for production environment) config -- servers:
-- config1: 27041
-- config2: 27042
-- config3: 27043

-- In three separate command windows, give the following commands:
mongod --shardsvr --replSet shard1 --dbpath c:\data\shard1\shard1a --logpath shard1a.log -port 27021
mongod --shardsvr --replSet shard1 --dbpath c:\data\shard1\shard1b --logpath shard1b.log -port 27022
mongod --shardsvr --replSet shard1 --dbpath c:\data\shard1\shard1c --logpath shard1c.log -port 27023

-- In one command window, give the following command:
mongo --port 27021
-- and then 
config = {_id: 'shard1', members: [
	{_id: 0, host: 'localhost:27021'},
	{_id: 1, host: 'localhost:27022'},
	{_id: 2, host: 'localhost:27023'},
] }
rs.initiate (config)
rs.status()

-- Similarly for the second shard:
mongod --shardsvr --replSet shard2 --dbpath c:\data\shard2\shard2a --logpath shard2a.log -port 27031
mongod --shardsvr --replSet shard2 --dbpath c:\data\shard2\shard2b --logpath shard2b.log -port 27032
mongod --shardsvr --replSet shard2 --dbpath c:\data\shard2\shard2c --logpath shard2c.log -port 27033
mongo --port 27031
config = {_id: 'shard2', members: [
	{_id: 0, host: 'localhost:27031'},
	{_id: 1, host: 'localhost:27032'},
	{_id: 2, host: 'localhost:27033'},
] }
rs.initiate (config)
rs.status()

-- Now for config servers
-- directories: c:\data\config1, 2, 3
mongod --configsvr --dbpath c:\data\config1 --logpath config1.log --port 27041
mongod --configsvr --dbpath c:\data\config2 --logpath config2.log --port 27042
mongod --configsvr --dbpath c:\data\config3 --logpath config3.log --port 27043

-- Now for mongos (no port number given, so standard port)
mongos --logpath mongos.log --configdb localhost:27041,localhost:27042,localhost:27043

-- Now connect mongo shell to mongos (no port number given, so standard port)
mongo 
db.adminCommand ( {addshard: 'shard1/localhost:27021'} )
db.adminCommand ( {addshard: 'shard2/localhost:27031'} )
db.adminCommand ( {enableSharding: 'test'} )
db.adminCommand ( {shardCollection: 'test.persons', key: {name: 1} } )
sh.status()
db.persons.stats()
db.persons.find(...).explain()

----------------------------------
- Sharding, on physical machines
----------------------------------

-- shard1, on all three machines give the same command as follows:
mongod --shardsvr --replSet shard1

-- shard2, on all three machines give the command as follows:
mongod --shardsvr --replSet shard2

-- shard3 on all three machines give the command as follows:
mongod --shardsvr --replSet shard3

-- In client machine:
mongo 172.16.11.19:27018

-- and then 
config = {_id: 'shard1', members: [
	{_id: 0, host: '172.16.11.19:27018'},
	{_id: 1, host: '172.16.11.242:27018'},
	{_id: 2, host: '172.16.11.184:27018'}
] }
rs.initiate (config)
rs.status()

-- In another client window:
mongo 172.16.11.250:27018
config = {_id: 'shard2', members: [
	{_id: 0, host: '172.16.11.250:27018'},
	{_id: 1, host: '172.16.11.244:27018'},
	{_id: 2, host: '172.16.11.249:27018'},
	{_id: 3, host: '172.16.11.23:27018'},
] }
rs.initiate (config)
rs.status()

-- Similarly in third client window for shard3
config = {_id: 'shard1', members: [
	{_id: 0, host: '172.16.11.212:27018'},
	{_id: 1, host: '172.16.11.246:27018'},
	{_id: 2, host: '172.16.11.76:27018'}
] }
rs.initiate (config)
rs.status()

-- To create config servers on 3 machines, on each of them run (these machines should have c:\data\configdb folder)

mongod --configsvr 
mongod --configsvr 
mongod --configsvr 

-- Now for mongos (no port number given, so standard port)
mongos --configdb 172.16.11.44:27019,172.16.11.177:27019,172.16.11.243:27019

-- Another client window, to connect to mongos (no port number given, so standard port)
mongo 172.16.11.241

sh.addShard ('shard1/172.16.11.19:27018')
sh.addShard ('shard1/172.16.11.250:27018')
sh.addShard ('shard1/172.16.11.212:27018')

-- or

db.adminCommand ( {addshard: 'shard1/172.16.11.19:27018'} )
db.adminCommand ( {addshard: 'shard2/172.16.11.250:27018'} )
db.adminCommand ( {addshard: 'shard3/172.16.11.212:27018'} )

sh.shardCollection ('pragati.persons', {name: 1}, true)

db.adminCommand ( {enableSharding: 'pragati'} )
db.adminCommand ( {shardCollection: 'pragati.persons', key: {name: 1} } )
sh.status()


db.persons.stats()
db.persons.find(...).explain()

mongos> show collections
actionlog
changelog
chunks
collections
databases
employees
lockpings
locks
mongos
pradyumn.friends
settings
shards
system.indexes
tags
version

mongos> db.chunks.findOne()
{
        "_id" : "pragati.persons-name_MinKey",
        "lastmod" : Timestamp(1, 0),
        "lastmodEpoch" : ObjectId("5565afd364a5abcad2436d40"),
        "ns" : "pragati.persons",
        "min" : {
                "name" : { "$minKey" : 1 }
        },
        "max" : {
                "name" : { "$maxKey" : 1 }
        },
        "shard" : "shard1"
}


mongos> db.collections.findOne()
{
        "_id" : "pragati.persons",
        "lastmod" : ISODate("2015-05-27T11:51:47.326Z"),
        "dropped" : false,
        "key" : {
                "name" : 1
        },
        "unique" : false,
        "lastmodEpoch" : ObjectId("5565afd364a5abcad2436d40")
}



mongos> db.databases.find()
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
{ "_id" : "pragati", "partitioned" : true, "primary" : "shard1" }
{ "_id" : "pradyumn", "partitioned" : true, "primary" : "shard1" }



mongos> db.mongos.find().pretty()
{
        "_id" : "trg1525:27017",
        "ping" : ISODate("2015-06-01T08:42:15.221Z"),
        "up" : 168392,
        "waiting" : true,
        "mongoVersion" : "3.0.1"
}
{
        "_id" : "trg1984:27017",
        "ping" : ISODate("2015-05-28T12:33:38.106Z"),
        "up" : 1708,
        "waiting" : false,
        "mongoVersion" : "3.0.1"
}





mongos> db.settings.find().pretty()
{ "_id" : "chunksize", "value" : 64 }




mongos> db.shards.find().pretty()
{
        "_id" : "shard1",
        "host" : "shard1/172.16.11.184:27018,172.16.11.19:27018,172.16.11.242:27018"
}
{
        "_id" : "shard2",
        "host" : "shard2/172.16.11.23:27018,172.16.11.244:27018,172.16.11.249:27018,172.16.11.250:27018"
}
{
        "_id" : "shard3",
        "host" : "shard3/172.16.11.212:27018,172.16.11.246:27018,172.16.11.76:27018"
}





mongos> use admin
switched to db admin
mongos> db.runCommand ( {listShards: 1} )
{
        "shards" : [
                {
                        "_id" : "shard1",
                        "host" : "shard1/172.16.11.184:27018,172.16.11.19:27018,172.16.11.242:27018"
                },
                {
                        "_id" : "shard2",
                        "host" : "shard2/172.16.11.23:27018,172.16.11.244:27018,172.16.11.249:27018,172.16.11.250:27018"
                },
                {
                        "_id" : "shard3",
                        "host" : "shard3/172.16.11.212:27018,172.16.11.246:27018,172.16.11.76:27018"
                }
        ],
        "ok" : 1
}



mongos> sh.status()
--- Sharding Status ---
  sharding version: {
        "_id" : 1,
        "minCompatibleVersion" : 5,
        "currentVersion" : 6,
        "clusterId" : ObjectId("5565ad8f64a5abcad2436ccb")
}
  shards:
        {  "_id" : "shard1",  "host" : "shard1/172.16.11.184:27018,172.16.11.19:27018,172.16.11.242:27018" }
        {  "_id" : "shard2",  "host" : "shard2/172.16.11.23:27018,172.16.11.244:27018,172.16.11.249:27018,172.16.11.250:27018" }
        {  "_id" : "shard3",  "host" : "shard3/172.16.11.212:27018,172.16.11.246:27018,172.16.11.76:27018" }
  balancer:
        Currently enabled:  yes
        Currently running:  no
        Failed balancer rounds in last 5 attempts:  0
        Migration Results for the last 24 hours:
                No recent migrations
  databases:
        {  "_id" : "admin",  "partitioned" : false,  "primary" : "config" }
        {  "_id" : "pragati",  "partitioned" : true,  "primary" : "shard1" }
                pragati.employees
                        shard key: { "name" : 1 }
                        chunks:
                                shard1  1
                        { "name" : { "$minKey" : 1 } } -->> { "name" : { "$maxKey" : 1 } } on : shard1 Timestamp(1, 0)
                pragati.persons
                        shard key: { "name" : 1 }
                        chunks:
                                shard1  1
                        { "name" : { "$minKey" : 1 } } -->> { "name" : { "$maxKey" : 1 } } on : shard1 Timestamp(1, 0)
        {  "_id" : "pradyumn",  "partitioned" : true,  "primary" : "shard1" }






sh.stopBalancer ()
sh.getBalancerState()
sh.startBalancer()




sh.disableBalancing ('pradyumn.persons')
sh.enableBalancing ('pradyumn.persons')






------  Removing a shard

sh.status()
use admin
db.runCommand ( {removeShard: 'shard3'} )

mongos> use admin
switched to db admin
mongos> db.runCommand ( {removeShard: 'shard3'} )
{
        "msg" : "draining started successfully",
        "state" : "started",
        "shard" : "shard3",
        "ok" : 1
}

mongos> db.runCommand ( {removeShard: 'shard3'} )
{
        "msg" : "removeshard completed successfully",
        "state" : "completed",
        "shard" : "shard3",
        "ok" : 1
}



db.runCommand ( {movePrimary: 'pradyumn.zips', to: 'shard2'} )




------ Changing the chunk size

use config
db.settings.save ( {_id: 'chunksize', value: 1})

--------------------------
- Configuration file
--------------------------

-- Create a file c:\config\config.txt as follows:
systemLog:
    destination: file
    path: "c:\\data\\log\\pragati.log"
    logAppend: false
    verbosity: 5

-- Start mongod as follows:
mongod --config c:\data\config\config.txt

--------------------------
- Authentication
--------------------------

use admin
db.createUser ( {
	user: 'pradyumn',
	pwd: 'mark',
	roles: [
		{role: 'readWrite', db: 'pradyumn'}, 
		{role: 'read', db: 'pragati'}
	]
} )

db.createUser ( {
	user: 'superuser',
	pwd: 'superpwd',
	roles: ['root']
})

db.createUser ( {
	user: 'santosh',
	pwd: 'gond',
	roles: [ {role: 'userAdminAnyDatabase', db: 'admin'} ]
} )

db.createUser ( {
	user: 'mahendra',
	pwd: 'singh',
	roles: [ {role: 'userAdmin', db: 'pradyumn'} ]
} )

mongod --config c:\data\config\config.txt --auth

mongo -u superuser -p superpwd -authenticationDatabase admin

mongo -u pradyumn -p mark -authenticationDatabase admin

mongo -u santosh -p gond -authenticationDatabase admin

db.createUser ( {
	user: 'roger',
	pwd: 'roger',
	roles: [ {role: 'read', db: 'pradyumn'} ]
} )

db.dropUser ('pradyumn')

use admin
db.createRole ( {
	role: 'hrExecutive',
	roles: [
		{role: 'read', db: 'pradyumn'},
		{role: 'read', db: 'pragati'}
	],
	privileges: [
		{resource: {db: 'pradyumn', collection: 'zips'}, actions: ['insert', 'remove']},
		{resource: {db: '', collection: ''}, actions: ['changeOwnPassword']}
	]
} )

db.createUser ( {
	user: 'preeti',
	pwd: 'mark',
	roles: [
		{role: 'hrExecutive', db: 'admin'}
	]
} )

mongo -u preeti -p mark -authenticationDatabase admin

db.updateUser (
	'preeti',
	{pwd: 'changeit'}
)

-- fails as right not granted to pradyumn

mongo -u pradyumn -p mark -authenticationDatabase admin

db.updateUser (
	'pradyumn',
	{pwd: 'changeit'}
)

mongo -u superuser -p superpwd -authenticationDatabase admin
use admin
db.grantRolesToUser (
	'pradyumn',
	[
		{role: 'hrExecutive', db: 'admin'}
	]
)

-- Identify a user's roles

db.getUser ('pradyumn')
--output:
> db.getUser ('pradyumn')
{
        "_id" : "admin.pradyumn",
        "user" : "pradyumn",
        "db" : "admin",
        "roles" : [
                {
                        "role" : "readWrite",
                        "db" : "pradyumn"
                },
                {
                        "role" : "read",
                        "db" : "pragati"
                },
                {
                        "role" : "hrExecutive",
                        "db" : "admin"
                }
        ]
}

-- Identify privileges for a role

use admin
db.getRole ('hrExecutive', {showPrivileges: true})

-- Revoke a role from a user
db.revokeRolesFromUser (
	'pradyumn',
	[
		{role: 'hrExecutive', db: 'admin'}
	]
)

-- View a role in current database

db.runCommand ( {rolesInfo: 'hrExecutive'} )
--Output
> db.runCommand ( {rolesInfo: 'hrExecutive'} )
{
        "roles" : [
                {
                        "role" : "hrExecutive",
                        "db" : "admin",
                        "isBuiltin" : false,
                        "roles" : [
                                {
                                        "role" : "read",
                                        "db" : "pradyumn"
                                },
                                {
                                        "role" : "read",
                                        "db" : "pragati"
                                }
                        ],
                        "inheritedRoles" : [
                                {
                                        "role" : "read",
                                        "db" : "pradyumn"
                                },
                                {
                                        "role" : "read",
                                        "db" : "pragati"
                                }
                        ]
                }
        ],
        "ok" : 1
}

-- View a role in a different database

use pradyumn
db.runCommand ( {rolesInfo: {role: 'hrExecutive', db: 'admin'} } )

-- View all custom roles
use admin
db.system.roles.find()

-- Change a user's password

db.changeUserPassword ('pradyumn', 'changeit')

--------------------------
- Write Concern
--------------------------

db.persons.insert ( 
{
	name: {first: 'Salil', last: 'Gupta'},
	gender: 'M',
	yearOfBirth: 1960,
	livesIn: 'Mumbai',
	counriesVisited: ['India', 'United States of America', 'Netherlands', 'China'],
	languages: [
		{name: 'English', proficiency: 'Fluent'},
		{name: 'Hindi', proficiency: 'Intermediate'}],
	married: 'Yes'
},
{writeConcern: {w: 'majority', wtimeout: 5000}}	
)



--------------------------
- Profiler
--------------------------

mongod --profile 1 --slowms 2
mongo
db.scores.find({student_id: 1})
db.system.profile.find().pretty()
db.system.profile.find( {ns: 'pragati.scores'}).sort ({millis: -1}).pretty()
db.getProfilingLevel()
db.getProfilingStatus()
db.setProfilingLevel (1, 10)
db.setProfilingLevel (0)

-----------------------
- Sundry, to add in PPT
-----------------------

db.stats()

-- Running a command on another database

use test
db.getSiblingDB ("pragati").persons.count()

-- Compact space

db.adminCommand ({repairDatabase: 1})
	
-----------------------------
- Simulating auto-increment
-----------------------------

db.counters.insert ( {_id: 'employeeid', seq: 0} )

function getNextSequence(name) {
   var ret = db.counters.findAndModify(
          {
            query: { _id: name },
            update: { $inc: { seq: 1 } },
            new: true
          }
   );

   return ret.seq;
}
db.employees.insert ( {_id: getNextSequence ('employeeid'), name: 'Bhagyarekha Sonar'} )
db.employees.insert ( {_id: getNextSequence ('employeeid'), name: 'Sophia Andrade'} )
db.employees.insert ( {_id: getNextSequence ('employeeid'), name: 'Gopal Mirani'} )

---------------------------
- Mongodump
---------------------------

mongodump --help
mongodump /h 172.16.11.241 /d pradyumn /c zips /o dumpoutputs
mongodump /h 172.16.11.241 /d pradyumn /o dumpoutputs
mongodump /h 172.16.11.241 /o dumpoutputs

mongorestore /h 172.16.11.241 /d pradyumn /c zips /dir: dumpoutputs\pradyumn\zips.bson

mongorestore /h 172.16.11.241 /d pradyumn /dir: dumpoutputs\pradyumn
mongorestore /h 172.16.11.241 /d pradyumn /dir: dumpoutputs\pradyumn /drop


----------------------
- Users
----------------------

db.createUser (
	{user: 'pradyumn', pwd: 'idontknow', roles: ['readWrite', 'dbAdmin'] }
)

--------------------
- Homework 4.3
--------------------

db.posts.ensureIndex ({date: -1})
db.posts.ensureIndex ({tags: 1, date: -1})
db.posts.ensureIndex ({permalink:1})

--------------------
- Homework 4.4
--------------------

db.profile.find ( {"ns": "school2.students"}).sort( {millis: -1}).limit(1).pretty()

--------------------
- Homework 5.1
--------------------

db.posts.aggregate (
	{$project: {_id:1, comments: 1} },
	{$unwind: '$comments'},
	{$group: {_id: '$comments.author', comms: {$sum: 1} } },
	{$sort: {comms: 1}}
)


----------------------
- Homework 5.2
----------------------

db.zips.aggregate (
	{$match: {state: {$in: ['CA', 'NY'] } } },
	{$group: {_id: {state: '$state', city: '$city'}, population: {$sum: '$pop'} } },
	{$match: {population: {$gt: 25000} } },
	{$group: {_id: 1, avgpop: {$avg: '$population'} } }
)

----------------------
- Homework 5.3
----------------------

-- Steps
-- 1. Denormalize scores with $unwind
-- 2. Drop quiz scores with $match
-- 3. Get average marks for class-student combination with $group
-- 4. Get average marks for class with $group
-- 5. Sort in descending order of average marks with $sort
-- 6. (Optional) limit the output to 1 document with $limit

db.grades.aggregate (
	{$unwind: '$scores'},
	{$match: {'scores.type' : {$in: ['exam', 'homework'] } } },
	{$group: {_id: {class_id: '$class_id', student_id: '$student_id'}, average_marks: {$avg: '$scores.score'} } },
	{$group: {_id: {class_id: '$_id.class_id'}, average_marks: {$avg: '$average_marks'} } },
	{$sort: {average_marks: -1} },
	{$limit: 1}
)

----------------------
- Homework 5.4
----------------------

db.zips.aggregate (
	{$project: {_id: 1, firstchar: {$substr: ['$city', 0, 1] }, pop: 1} },
	{$match: {firstchar: {$in: ['1', '2', '3', '4', '5', '6', '7', '8', '9', '0'] } } },
	{$group: {_id: 1, ruralpopulation: {$sum: '$pop'} } }
)

----------------------
- Final Exam 1
----------------------

db.messages.find ( {'headers.From': 'andrew.fastow@enron.com', 'headers.To': 'jeff.skilling@enron.com'} ).count()

----------------------
- Final Exam 2
----------------------

db.messages.aggregate (
	{$project: {from: '$headers.From', to: '$headers.To'} },
	{$unwind: '$to'},
	{$group: {_id: {_id: '$_id', from: '$from'}, to: {$addToSet: '$to'} } },
	{$unwind: '$to'},
	{$group: {_id: {from: '$_id.from', to: '$to'}, mail_count: {$sum: 1} } },
	{$sort: {mail_count: -1} }
)