Elite Document Structure
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Questions on this database can be found hereMAPREDUCE elite
Document Structure
Unlike the previous examples, here we'll be using nested documents. A nested document is simply a document that contains other documents, for example:
[{"name":"Jim",
"role":"Dad",
"age": 42,
"children":[{"name":"Bob", "age":2},
{"name":"Alice", "age":3}
]
}]
Another change from the previous example is that null and empty values are no longer stored.
This means that some documents will have fields that others do not. Some systems will be uninhabited and have no stations. Some stations will have no listings.
To query null or non-existant fields we use <field>: null
The average commodities document looks something like this.
{
"_id" : ObjectId("55af74e7402aa43f1ce7e3a3"),
"name" : "Explosives",
"average_price" : 267,
"category" : "Chemicals"
}
systems is much bigger, so some stations and listings have been removed from this example
> db.systems.findOne({"name":"1 Kappa Cygni"})
{
"_id" : ObjectId("55b0e227369fd571eca8764c"),
"stations" : [
{
"max_landing_pad_size" : "M",
"has_blackmarket" : 0,
"has_commodities" : 1,
"updated_at" : 1434929486,
"has_outfitting" : 0,
"government" : "Democracy",
"state" : null,
"has_shipyard" : 0,
"type" : "Unknown Outpost",
"has_rearm" : 0,
"allegiance" : "Federation",
"has_refuel" : 1,
"name" : "Kinsey Ring",
"listings" : [
{
"commodity" : "Hydrogen Fuel",
"supply" : 129630,
"collected_at" : 1421669319,
"update_count" : "1",
"buy_price" : 93,
"sell_price" : 89,
"demand" : 0
},
{
"commodity" : "Mineral Oil",
"supply" : 0,
"collected_at" : 1421669320,
"update_count" : "1",
"buy_price" : 0,
"sell_price" : 326,
"demand" : 217674
},
],
"distance_to_star" : 2359,
"economies" : [
"Industrial",
"Refinery"
],
"has_repair" : 1
},
{
"max_landing_pad_size" : "L",
"has_blackmarket" : 1,
"has_commodities" : 0,
"updated_at" : 1434929486,
"has_outfitting" : 1,
"government" : "Democracy",
"state" : null,
"has_shipyard" : 1,
"type" : "Unknown Starport",
"has_rearm" : 1,
"allegiance" : "Federation",
"has_refuel" : 1,
"name" : "Wohler Port",
"distance_to_star" : 3520,
"economies" : [
"Industrial",
"Refinery"
],
"has_repair" : 1
}
],
"name" : "1 Kappa Cygni",
"faction" : "United 1 Kappa Cygni Future",
"government" : "Democracy",
"allegiance" : "Federation",
"updated_at" : 1430938622,
"state" : "None",
"needs_permit" : 0,
"y" : 37.78125,
"x" : -117.75,
"security" : "High",
"z" : 11.1875,
"primary_economy" : "Industrial",
"population" : 24843190
}
Here is a list of all the keys used.
commodities:
_id, average_price, category, name
systems:
_id, allegiance, faction, government, name, population, primary_economy, security, state, stations, updated_at, x, y, z
systems.stations:
allegiance, distance_to_star, economies, export_commodities,has_blackmarket, has_commodities, has_rearm, has_repair,
has_shipyard, has_outfitting, faction, government, listings, max_landing_pad, name, state, type, updated_at
systems.stations.listings:
buy_price, collected_at, demand, commodity, sell_price, supply, update_count