examples aggregation

Author: inventriz

custom-js/10limit.js

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+use agg
+db.aggr.aggregate([
+    {$match:
+     {
+	 state:"NY"
+     }
+    },
+    {$group:
+     {
+	 _id: "$city",
+	 population: {$sum:"$pop"},
+     }
+    },
+    {$project:
+     {
+	 _id: 0,
+	 city: "$_id",
+	 population: 1,
+     }
+    },
+    {$sort:
+     {
+	 population:-1
+     }
+    },
+    {$skip: 10},
+    {$limit: 5}
+])
+
+

custom-js/1match.js

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+use agg;
+db.aggr.aggregate([
+    {$match:
+     {
+	 state:"NY"
+     }
+    }
+]);

custom-js/2match_and_group.js

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+use agg
+db.aggr.aggregate([
+    {$match:
+     {
+	 state:"NY"
+     }
+    },
+    {$group:
+     {
+	 _id: "$city",
+	 population: {$sum:"$pop"},
+	 zip_codes: {$addToSet: "$_id"}
+     }
+    },
+	{$limit:5}
+])
+
+

custom-js/3match_group_and_project.js

@@ -0,0 +1,26 @@
+use agg
+db.aggr.aggregate([
+    {$match:
+     {
+	 state:"NY"
+     }
+    },
+    {$group:
+     {
+	 _id: "$city",
+	 population: {$sum:"$pop"},
+	 zip_codes: {$addToSet: "$_id"}
+     }
+    },
+    {$project:
+     {
+	 _id: 0,
+	 city: "$_id",
+	 population: 1,
+	 zip_codes:1
+     }
+    },
+	{$limit : 5}
+])
+
+

custom-js/4using_avg.js

@@ -0,0 +1,11 @@
+use agg
+db.aggr.aggregate([
+    {$group:
+     {
+	 _id: "$state",
+	 avg_pop:{$avg:"$pop"}
+     }
+    }
+])
+
+

custom-js/5using_addToSet.js

@@ -0,0 +1,13 @@
+use agg
+db.products.aggregate([
+    {$group:
+     {
+	 _id: {
+	     "maker":"$manufacturer"
+	 },
+	 categories:{$addToSet:"$category"}
+     }
+    }
+])
+
+

custom-js/6using_max.js

@@ -0,0 +1,19 @@
+use agg
+db.aggr.aggregate([
+    {$match:
+     {
+	 state:"NY"
+     }
+    },
+	{$group:
+     {
+	 _id: "$city",
+	 max_pop:{$max:"$pop"}
+     }
+    },
+	{$sort : {max_pop : -1} 
+	},
+	{$limit : 3}
+])
+
+

custom-js/7using_push.js

@@ -0,0 +1,13 @@
+use agg
+db.products.aggregate([
+    {$group:
+     {
+	 _id: {
+	     "maker":"$manufacturer"
+	 },
+	 categories:{$push:"$category"}
+     }
+    }
+])
+
+

custom-js/8using_sum.js

@@ -0,0 +1,13 @@
+use agg
+db.products.aggregate([
+    {$group:
+     {
+	 _id: {
+	     "maker":"$manufacturer"
+	 },
+	 sum_prices:{$sum:"$price"}
+     }
+    }
+])
+
+

custom-js/9aggr.js

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+use foo
+db.aggr.aggregate([
+    /* get the population of every city in every state */
+    {$group:
+     {
+	 _id: {state:"$state", city:"$city"},
+	 population: {$sum:"$pop"},
+     }
+    } ,
+     /* sort by state, population */
+    {$sort: 
+     {"_id.state":1, "population":-1}
+    },
+    /* group by state, get the first item in each group */
+    {$group: 
+     {
+	 _id:"$_id.state",
+	 city: {$first: "$_id.city"},
+	 population: {$first:"$population"}
+     }
+    }
+])