db.crimes.createIndex(shift:1);
db.crimes.createIndex({shift:1, method:-1});

a)
db.crimes.count();
b)
db.crimes.find();

c)
db.crimes.find(
	{},
	{ '_id':0, 'properties.shift':1, 'properties.method':1, 'properties.district':1 }
);

d)
db.crimes.find(
	{},
	{ '_id':0, 'properties.shift':1, 'properties.method':1, 'properties.district':1 }
	).sort({'properties.district':1}
);

e)
db.crimes.find(
	{},
	{ '_id':0, 'properties.shift':1, 'properties.method':1, 'properties.district':1 }
).sort({'properties.district':1}).limit(100);

f)
db.crimes.find(
	{},
	{ '_id':0, 'properties.shift':1, 'properties.method':1, 'properties.district':1 }
).sort({'properties.district':1}).skip(100).limit(100);

g)
db.crimes.find(
	{'properties.district': { $gte : 1, $lte : 5}},
	{ '_id':0, 'properties.report_date':1, 'properties.district':1 }
).sort({'properties.district':1, 'properties.report_date':-1});
ou
db.crimes.aggregate([
	{ $match : {'properties.district': { $gte : 1, $lte : 5}}},
	{ $sort : { 'properties.district':1, 'properties.report_date':-1}}
]);

h)
db.crimes.find(
	{'properties.district': { $gte : 1, $lte : 5}},
	{ '_id':0, 'properties.report_date':1, 'properties.district':1 }
).sort({'properties.district':1, 'properties.report_date':-1}).explain();

i)
db.crimes.createIndex({district:1});

j)
db.crimes.find(
	{'properties.neighborho': 'Cluster 6'},
	{ 'properties.neighborho':1 }
);

k)
db.crimes.find(
	{'properties.neighborho': 'Cluster 2'},
	{ '_id':0, 'properties.block':1, 'type':1 }
);

l)
db.crimes.find(
	{'properties.neighborho':'Cluster 2'},
	{'properties.block':1, 'properties.offence':1}
);

m)
db.crimes.find(
	{'properties.report_date':{$regex: '2018-01'}},
	{'properties.report_date':1, 'properties.block':1, 'properties.method':1, 'properties.shift':1, 'type':1}
);

n)
db.crimes.distinct(
	'properties.offense',
	{'properties.shift':'DAY'}
);

o)
db.crimes.distinct(
	'properties.offense',
	{'properties.shift':'MIDNIGHT'}
);

p)
db.crimes.find(
	{'properties.shift':'MIDNIGHT'},
	{'properties.shift':1, 'type':1}
).explain();

q)
db.crimes.find({'properties.method': {$regex: 'GUN'}}, {});

r)
db.crimes.find({'properties.method': {$regex: 'GUN'}}, {}).explain;

s)
db.crimes.distinct('properties.method');