How can I (in MongoDB) combine data from multiple collections into one collection?
Can I use map-reduce and if so then how?
I would greatly appreciate some example as I am a novice.
MongoDB 3.2 now allows one to combine data from multiple collections into one through the $lookup aggregation stage. As a practical example, lets say that you have data about books split into two different collections.
First collection, called books, having the following data:
{
"isbn": "978-3-16-148410-0",
"title": "Some cool book",
"author": "John Doe"
}
{
"isbn": "978-3-16-148999-9",
"title": "Another awesome book",
"author": "Jane Roe"
}
And the second collection, called books_selling_data, having the following data:
{
"_id": ObjectId("56e31bcf76cdf52e541d9d26"),
"isbn": "978-3-16-148410-0",
"copies_sold": 12500
}
{
"_id": ObjectId("56e31ce076cdf52e541d9d28"),
"isbn": "978-3-16-148999-9",
"copies_sold": 720050
}
{
"_id": ObjectId("56e31ce076cdf52e541d9d29"),
"isbn": "978-3-16-148999-9",
"copies_sold": 1000
}
To merge both collections is just a matter of using $lookup in the following way:
db.books.aggregate([{
$lookup: {
from: "books_selling_data",
localField: "isbn",
foreignField: "isbn",
as: "copies_sold"
}
}])
After this aggregation, the books collection will look like the following:
{
"isbn": "978-3-16-148410-0",
"title": "Some cool book",
"author": "John Doe",
"copies_sold": [
{
"_id": ObjectId("56e31bcf76cdf52e541d9d26"),
"isbn": "978-3-16-148410-0",
"copies_sold": 12500
}
]
}
{
"isbn": "978-3-16-148999-9",
"title": "Another awesome book",
"author": "Jane Roe",
"copies_sold": [
{
"_id": ObjectId("56e31ce076cdf52e541d9d28"),
"isbn": "978-3-16-148999-9",
"copies_sold": 720050
},
{
"_id": ObjectId("56e31ce076cdf52e541d9d28"),
"isbn": "978-3-16-148999-9",
"copies_sold": 1000
}
]
}
It is important to note a few things:
The "from" collection, in this case books_selling_data, cannot be sharded.
The "as" field will be an array, as the example above.
Both "localField" and "foreignField" options on the $lookup stage will be treated as null for matching purposes if they don't exist in their respective collections (the $lookup docs has a perfect example about that).
So, as a conclusion, if you want to consolidate both collections, having, in this case, a flat copies_sold field with the total copies sold, you will have to work a little bit more, probably using an intermediary collection that will, then, be $out to the final collection.
Although you can't do this real-time, you can run map-reduce multiple times to merge data together by using the "reduce" out option in MongoDB 1.8+ map/reduce (see http://www.mongodb.org/display/DOCS/MapReduce#MapReduce-Outputoptions). You need to have some key in both collections that you can use as an _id.
For example, let's say you have a users collection and a comments collection and you want to have a new collection that has some user demographic info for each comment.
Let's say the users collection has the following fields:
_id
firstName
lastName
country
gender
age
And then the comments collection has the following fields:
_id
userId
comment
created
You would do this map/reduce:
var mapUsers, mapComments, reduce;
db.users_comments.remove();
// setup sample data - wouldn't actually use this in production
db.users.remove();
db.comments.remove();
db.users.save({firstName:"Rich",lastName:"S",gender:"M",country:"CA",age:"18"});
db.users.save({firstName:"Rob",lastName:"M",gender:"M",country:"US",age:"25"});
db.users.save({firstName:"Sarah",lastName:"T",gender:"F",country:"US",age:"13"});
var users = db.users.find();
db.comments.save({userId: users[0]._id, "comment": "Hey, what's up?", created: new ISODate()});
db.comments.save({userId: users[1]._id, "comment": "Not much", created: new ISODate()});
db.comments.save({userId: users[0]._id, "comment": "Cool", created: new ISODate()});
// end sample data setup
mapUsers = function() {
var values = {
country: this.country,
gender: this.gender,
age: this.age
};
emit(this._id, values);
};
mapComments = function() {
var values = {
commentId: this._id,
comment: this.comment,
created: this.created
};
emit(this.userId, values);
};
reduce = function(k, values) {
var result = {}, commentFields = {
"commentId": '',
"comment": '',
"created": ''
};
values.forEach(function(value) {
var field;
if ("comment" in value) {
if (!("comments" in result)) {
result.comments = [];
}
result.comments.push(value);
} else if ("comments" in value) {
if (!("comments" in result)) {
result.comments = [];
}
result.comments.push.apply(result.comments, value.comments);
}
for (field in value) {
if (value.hasOwnProperty(field) && !(field in commentFields)) {
result[field] = value[field];
}
}
});
return result;
};
db.users.mapReduce(mapUsers, reduce, {"out": {"reduce": "users_comments"}});
db.comments.mapReduce(mapComments, reduce, {"out": {"reduce": "users_comments"}});
db.users_comments.find().pretty(); // see the resulting collection
At this point, you will have a new collection called users_comments that contains the merged data and you can now use that. These reduced collections all have _id which is the key you were emitting in your map functions and then all of the values are a sub-object inside the value key - the values aren't at the top level of these reduced documents.
This is a somewhat simple example. You can repeat this with more collections as much as you want to keep building up the reduced collection. You could also do summaries and aggregations of data in the process. Likely you would define more than one reduce function as the logic for aggregating and preserving existing fields gets more complex.
You'll also note that there is now one document for each user with all of that user's comments in an array. If we were merging data that has a one-to-one relationship rather than one-to-many, it would be flat and you could simply use a reduce function like this:
reduce = function(k, values) {
var result = {};
values.forEach(function(value) {
var field;
for (field in value) {
if (value.hasOwnProperty(field)) {
result[field] = value[field];
}
}
});
return result;
};
If you want to flatten the users_comments collection so it's one document per comment, additionally run this:
var map, reduce;
map = function() {
var debug = function(value) {
var field;
for (field in value) {
print(field + ": " + value[field]);
}
};
debug(this);
var that = this;
if ("comments" in this.value) {
this.value.comments.forEach(function(value) {
emit(value.commentId, {
userId: that._id,
country: that.value.country,
age: that.value.age,
comment: value.comment,
created: value.created,
});
});
}
};
reduce = function(k, values) {
var result = {};
values.forEach(function(value) {
var field;
for (field in value) {
if (value.hasOwnProperty(field)) {
result[field] = value[field];
}
}
});
return result;
};
db.users_comments.mapReduce(map, reduce, {"out": "comments_with_demographics"});
This technique should definitely not be performed on the fly. It's suited for a cron job or something like that which updates the merged data periodically. You'll probably want to run ensureIndex on the new collection to make sure queries you perform against it run quickly (keep in mind that your data is still inside a value key, so if you were to index comments_with_demographics on the comment created time, it would be db.comments_with_demographics.ensureIndex({"value.created": 1});
Doing unions in MongoDB in a 'SQL UNION' fashion is possible using aggregations along with lookups, in a single query. Here is an example I have tested that works with MongoDB 4.0:
// Create employees data for testing the union.
db.getCollection('employees').insert({ name: "John", type: "employee", department: "sales" });
db.getCollection('employees').insert({ name: "Martha", type: "employee", department: "accounting" });
db.getCollection('employees').insert({ name: "Amy", type: "employee", department: "warehouse" });
db.getCollection('employees').insert({ name: "Mike", type: "employee", department: "warehouse" });
// Create freelancers data for testing the union.
db.getCollection('freelancers').insert({ name: "Stephany", type: "freelancer", department: "accounting" });
db.getCollection('freelancers').insert({ name: "Martin", type: "freelancer", department: "sales" });
db.getCollection('freelancers').insert({ name: "Doug", type: "freelancer", department: "warehouse" });
db.getCollection('freelancers').insert({ name: "Brenda", type: "freelancer", department: "sales" });
// Here we do a union of the employees and freelancers using a single aggregation query.
db.getCollection('freelancers').aggregate( // 1. Use any collection containing at least one document.
[
{ $limit: 1 }, // 2. Keep only one document of the collection.
{ $project: { _id: '$$REMOVE' } }, // 3. Remove everything from the document.
// 4. Lookup collections to union together.
{ $lookup: { from: 'employees', pipeline: [{ $match: { department: 'sales' } }], as: 'employees' } },
{ $lookup: { from: 'freelancers', pipeline: [{ $match: { department: 'sales' } }], as: 'freelancers' } },
// 5. Union the collections together with a projection.
{ $project: { union: { $concatArrays: ["$employees", "$freelancers"] } } },
// 6. Unwind and replace root so you end up with a result set.
{ $unwind: '$union' },
{ $replaceRoot: { newRoot: '$union' } }
]);
Here is the explanation of how it works:
Instantiate an aggregate out of any collection of your database that has at least one document in it. If you can't guarantee any collection of your database will not be empty, you can workaround this issue by creating in your database some sort of 'dummy' collection containing a single empty document in it that will be there specifically for doing union queries.
Make the first stage of your pipeline to be { $limit: 1 }. This will strip all the documents of the collection except the first one.
Strip all the fields of the remaining document by using a $project stage:
{ $project: { _id: '$$REMOVE' } }
Your aggregate now contains a single, empty document. It's time to add lookups for each collection you want to union together. You may use the pipeline field to do some specific filtering, or leave localField and foreignField as null to match the whole collection.
{ $lookup: { from: 'collectionToUnion1', pipeline: [...], as: 'Collection1' } },
{ $lookup: { from: 'collectionToUnion2', pipeline: [...], as: 'Collection2' } },
{ $lookup: { from: 'collectionToUnion3', pipeline: [...], as: 'Collection3' } }
You now have an aggregate containing a single document that contains 3 arrays like this:
{
Collection1: [...],
Collection2: [...],
Collection3: [...]
}
You can then merge them together into a single array using a $project stage along with the $concatArrays aggregation operator:
{
"$project" :
{
"Union" : { $concatArrays: ["$Collection1", "$Collection2", "$Collection3"] }
}
}
You now have an aggregate containing a single document, into which is located an array that contains your union of collections. What remains to be done is to add an $unwind and a $replaceRoot stage to split your array into separate documents:
{ $unwind: "$Union" },
{ $replaceRoot: { newRoot: "$Union" } }
Voilà. You now have a result set containing the collections you wanted to union together. You can then add more stages to filter it further, sort it, apply skip() and limit(). Pretty much anything you want.
Starting Mongo 4.4, we can achieve this join within an aggregation pipeline by coupling the new $unionWith aggregation stage with $group's new $accumulator operator:
// > db.users.find()
// [{ user: 1, name: "x" }, { user: 2, name: "y" }]
// > db.books.find()
// [{ user: 1, book: "a" }, { user: 1, book: "b" }, { user: 2, book: "c" }]
// > db.movies.find()
// [{ user: 1, movie: "g" }, { user: 2, movie: "h" }, { user: 2, movie: "i" }]
db.users.aggregate([
{ $unionWith: "books" },
{ $unionWith: "movies" },
{ $group: {
_id: "$user",
user: {
$accumulator: {
accumulateArgs: ["$name", "$book", "$movie"],
init: function() { return { books: [], movies: [] } },
accumulate: function(user, name, book, movie) {
if (name) user.name = name;
if (book) user.books.push(book);
if (movie) user.movies.push(movie);
return user;
},
merge: function(userV1, userV2) {
if (userV2.name) userV1.name = userV2.name;
userV1.books.concat(userV2.books);
userV1.movies.concat(userV2.movies);
return userV1;
},
lang: "js"
}
}
}}
])
// { _id: 1, user: { books: ["a", "b"], movies: ["g"], name: "x" } }
// { _id: 2, user: { books: ["c"], movies: ["h", "i"], name: "y" } }
$unionWith combines records from the given collection within documents already in the aggregation pipeline. After the 2 union stages, we thus have all users, books and movies records within the pipeline.
We then $group records by $user and accumulate items using the $accumulator operator allowing custom accumulations of documents as they get grouped:
the fields we're interested in accumulating are defined with accumulateArgs.
init defines the state that will be accumulated as we group elements.
the accumulate function allows performing a custom action with a record being grouped in order to build the accumulated state. For instance, if the item being grouped has the book field defined, then we update the books part of the state.
merge is used to merge two internal states. It's only used for aggregations running on sharded clusters or when the operation exceeds memory limits.
Very basic example with $lookup.
db.getCollection('users').aggregate([
{
$lookup: {
from: "userinfo",
localField: "userId",
foreignField: "userId",
as: "userInfoData"
}
},
{
$lookup: {
from: "userrole",
localField: "userId",
foreignField: "userId",
as: "userRoleData"
}
},
{ $unwind: { path: "$userInfoData", preserveNullAndEmptyArrays: true }},
{ $unwind: { path: "$userRoleData", preserveNullAndEmptyArrays: true }}
])
Here is used
{ $unwind: { path: "$userInfoData", preserveNullAndEmptyArrays: true }},
{ $unwind: { path: "$userRoleData", preserveNullAndEmptyArrays: true }}
Instead of
{ $unwind:"$userRoleData"}
{ $unwind:"$userRoleData"}
Because { $unwind:"$userRoleData"} this will return empty or 0 result if no matching record found with $lookup.
If there is no bulk insert into mongodb, we loop all objects in the small_collection and insert them one by one into the big_collection:
db.small_collection.find().forEach(function(obj){
db.big_collection.insert(obj)
});
use multiple $lookup for multiple collections in aggregation
query:
db.getCollection('servicelocations').aggregate([
{
$match: {
serviceLocationId: {
$in: ["36728"]
}
}
},
{
$lookup: {
from: "orders",
localField: "serviceLocationId",
foreignField: "serviceLocationId",
as: "orders"
}
},
{
$lookup: {
from: "timewindowtypes",
localField: "timeWindow.timeWindowTypeId",
foreignField: "timeWindowTypeId",
as: "timeWindow"
}
},
{
$lookup: {
from: "servicetimetypes",
localField: "serviceTimeTypeId",
foreignField: "serviceTimeTypeId",
as: "serviceTime"
}
},
{
$unwind: "$orders"
},
{
$unwind: "$serviceTime"
},
{
$limit: 14
}
])
result:
{
"_id" : ObjectId("59c3ac4bb7799c90ebb3279b"),
"serviceLocationId" : "36728",
"regionId" : 1.0,
"zoneId" : "DXBZONE1",
"description" : "AL HALLAB REST EMIRATES MALL",
"locationPriority" : 1.0,
"accountTypeId" : 1.0,
"locationType" : "SERVICELOCATION",
"location" : {
"makani" : "",
"lat" : 25.119035,
"lng" : 55.198694
},
"deliveryDays" : "MTWRFSU",
"timeWindow" : [
{
"_id" : ObjectId("59c3b0a3b7799c90ebb32cde"),
"timeWindowTypeId" : "1",
"Description" : "MORNING",
"timeWindow" : {
"openTime" : "06:00",
"closeTime" : "08:00"
},
"accountId" : 1.0
},
{
"_id" : ObjectId("59c3b0a3b7799c90ebb32cdf"),
"timeWindowTypeId" : "1",
"Description" : "MORNING",
"timeWindow" : {
"openTime" : "09:00",
"closeTime" : "10:00"
},
"accountId" : 1.0
},
{
"_id" : ObjectId("59c3b0a3b7799c90ebb32ce0"),
"timeWindowTypeId" : "1",
"Description" : "MORNING",
"timeWindow" : {
"openTime" : "10:30",
"closeTime" : "11:30"
},
"accountId" : 1.0
}
],
"address1" : "",
"address2" : "",
"phone" : "",
"city" : "",
"county" : "",
"state" : "",
"country" : "",
"zipcode" : "",
"imageUrl" : "",
"contact" : {
"name" : "",
"email" : ""
},
"status" : "ACTIVE",
"createdBy" : "",
"updatedBy" : "",
"updateDate" : "",
"accountId" : 1.0,
"serviceTimeTypeId" : "1",
"orders" : [
{
"_id" : ObjectId("59c3b291f251c77f15790f92"),
"orderId" : "AQ18O1704264",
"serviceLocationId" : "36728",
"orderNo" : "AQ18O1704264",
"orderDate" : "18-Sep-17",
"description" : "AQ18O1704264",
"serviceType" : "Delivery",
"orderSource" : "Import",
"takenBy" : "KARIM",
"plannedDeliveryDate" : ISODate("2017-08-26T00:00:00.000Z"),
"plannedDeliveryTime" : "",
"actualDeliveryDate" : "",
"actualDeliveryTime" : "",
"deliveredBy" : "",
"size1" : 296.0,
"size2" : 3573.355,
"size3" : 240.811,
"jobPriority" : 1.0,
"cancelReason" : "",
"cancelDate" : "",
"cancelBy" : "",
"reasonCode" : "",
"reasonText" : "",
"status" : "",
"lineItems" : [
{
"ItemId" : "BNWB020",
"size1" : 15.0,
"size2" : 78.6,
"size3" : 6.0
},
{
"ItemId" : "BNWB021",
"size1" : 20.0,
"size2" : 252.0,
"size3" : 11.538
},
{
"ItemId" : "BNWB023",
"size1" : 15.0,
"size2" : 285.0,
"size3" : 16.071
},
{
"ItemId" : "CPMW112",
"size1" : 3.0,
"size2" : 25.38,
"size3" : 1.731
},
{
"ItemId" : "MMGW001",
"size1" : 25.0,
"size2" : 464.375,
"size3" : 46.875
},
{
"ItemId" : "MMNB218",
"size1" : 50.0,
"size2" : 920.0,
"size3" : 60.0
},
{
"ItemId" : "MMNB219",
"size1" : 50.0,
"size2" : 630.0,
"size3" : 40.0
},
{
"ItemId" : "MMNB220",
"size1" : 50.0,
"size2" : 416.0,
"size3" : 28.846
},
{
"ItemId" : "MMNB270",
"size1" : 50.0,
"size2" : 262.0,
"size3" : 20.0
},
{
"ItemId" : "MMNB302",
"size1" : 15.0,
"size2" : 195.0,
"size3" : 6.0
},
{
"ItemId" : "MMNB373",
"size1" : 3.0,
"size2" : 45.0,
"size3" : 3.75
}
],
"accountId" : 1.0
},
{
"_id" : ObjectId("59c3b291f251c77f15790f9d"),
"orderId" : "AQ137O1701240",
"serviceLocationId" : "36728",
"orderNo" : "AQ137O1701240",
"orderDate" : "18-Sep-17",
"description" : "AQ137O1701240",
"serviceType" : "Delivery",
"orderSource" : "Import",
"takenBy" : "KARIM",
"plannedDeliveryDate" : ISODate("2017-08-26T00:00:00.000Z"),
"plannedDeliveryTime" : "",
"actualDeliveryDate" : "",
"actualDeliveryTime" : "",
"deliveredBy" : "",
"size1" : 28.0,
"size2" : 520.11,
"size3" : 52.5,
"jobPriority" : 1.0,
"cancelReason" : "",
"cancelDate" : "",
"cancelBy" : "",
"reasonCode" : "",
"reasonText" : "",
"status" : "",
"lineItems" : [
{
"ItemId" : "MMGW001",
"size1" : 25.0,
"size2" : 464.38,
"size3" : 46.875
},
{
"ItemId" : "MMGW001-F1",
"size1" : 3.0,
"size2" : 55.73,
"size3" : 5.625
}
],
"accountId" : 1.0
},
{
"_id" : ObjectId("59c3b291f251c77f15790fd8"),
"orderId" : "AQ110O1705036",
"serviceLocationId" : "36728",
"orderNo" : "AQ110O1705036",
"orderDate" : "18-Sep-17",
"description" : "AQ110O1705036",
"serviceType" : "Delivery",
"orderSource" : "Import",
"takenBy" : "KARIM",
"plannedDeliveryDate" : ISODate("2017-08-26T00:00:00.000Z"),
"plannedDeliveryTime" : "",
"actualDeliveryDate" : "",
"actualDeliveryTime" : "",
"deliveredBy" : "",
"size1" : 60.0,
"size2" : 1046.0,
"size3" : 68.0,
"jobPriority" : 1.0,
"cancelReason" : "",
"cancelDate" : "",
"cancelBy" : "",
"reasonCode" : "",
"reasonText" : "",
"status" : "",
"lineItems" : [
{
"ItemId" : "MMNB218",
"size1" : 50.0,
"size2" : 920.0,
"size3" : 60.0
},
{
"ItemId" : "MMNB219",
"size1" : 10.0,
"size2" : 126.0,
"size3" : 8.0
}
],
"accountId" : 1.0
}
],
"serviceTime" : {
"_id" : ObjectId("59c3b07cb7799c90ebb32cdc"),
"serviceTimeTypeId" : "1",
"serviceTimeType" : "nohelper",
"description" : "",
"fixedTime" : 30.0,
"variableTime" : 0.0,
"accountId" : 1.0
}
}
Mongorestore has this feature of appending on top of whatever is already in the database, so this behavior could be used for combining two collections:
mongodump collection1
collection2.rename(collection1)
mongorestore
Didn't try it yet, but it might perform faster than the map/reduce approach.
Yes you can: Take this utility function that I have written today:
function shangMergeCol() {
tcol= db.getCollection(arguments[0]);
for (var i=1; i<arguments.length; i++){
scol= db.getCollection(arguments[i]);
scol.find().forEach(
function (d) {
tcol.insert(d);
}
)
}
}
You can pass to this function any number of collections, the first one is going to be the target one. All the rest collections are sources to be transferred to the target one.
Code snippet. Courtesy-Multiple posts on stack overflow including this one.
db.cust.drop();
db.zip.drop();
db.cust.insert({cust_id:1, zip_id: 101});
db.cust.insert({cust_id:2, zip_id: 101});
db.cust.insert({cust_id:3, zip_id: 101});
db.cust.insert({cust_id:4, zip_id: 102});
db.cust.insert({cust_id:5, zip_id: 102});
db.zip.insert({zip_id:101, zip_cd:'AAA'});
db.zip.insert({zip_id:102, zip_cd:'BBB'});
db.zip.insert({zip_id:103, zip_cd:'CCC'});
mapCust = function() {
var values = {
cust_id: this.cust_id
};
emit(this.zip_id, values);
};
mapZip = function() {
var values = {
zip_cd: this.zip_cd
};
emit(this.zip_id, values);
};
reduceCustZip = function(k, values) {
var result = {};
values.forEach(function(value) {
var field;
if ("cust_id" in value) {
if (!("cust_ids" in result)) {
result.cust_ids = [];
}
result.cust_ids.push(value);
} else {
for (field in value) {
if (value.hasOwnProperty(field) ) {
result[field] = value[field];
}
};
}
});
return result;
};
db.cust_zip.drop();
db.cust.mapReduce(mapCust, reduceCustZip, {"out": {"reduce": "cust_zip"}});
db.zip.mapReduce(mapZip, reduceCustZip, {"out": {"reduce": "cust_zip"}});
db.cust_zip.find();
mapCZ = function() {
var that = this;
if ("cust_ids" in this.value) {
this.value.cust_ids.forEach(function(value) {
emit(value.cust_id, {
zip_id: that._id,
zip_cd: that.value.zip_cd
});
});
}
};
reduceCZ = function(k, values) {
var result = {};
values.forEach(function(value) {
var field;
for (field in value) {
if (value.hasOwnProperty(field)) {
result[field] = value[field];
}
}
});
return result;
};
db.cust_zip_joined.drop();
db.cust_zip.mapReduce(mapCZ, reduceCZ, {"out": "cust_zip_joined"});
db.cust_zip_joined.find().pretty();
var flattenMRCollection=function(dbName,collectionName) {
var collection=db.getSiblingDB(dbName)[collectionName];
var i=0;
var bulk=collection.initializeUnorderedBulkOp();
collection.find({ value: { $exists: true } }).addOption(16).forEach(function(result) {
print((++i));
//collection.update({_id: result._id},result.value);
bulk.find({_id: result._id}).replaceOne(result.value);
if(i%1000==0)
{
print("Executing bulk...");
bulk.execute();
bulk=collection.initializeUnorderedBulkOp();
}
});
bulk.execute();
};
flattenMRCollection("mydb","cust_zip_joined");
db.cust_zip_joined.find().pretty();
You've to do that in your application layer. If you're using an ORM, it could use annotations (or something similar) to pull references that exist in other collections. I only have worked with Morphia, and the #Reference annotation fetches the referenced entity when queried, so I am able to avoid doing it myself in the code.
Related
I have a field distribution in record schema that looks likes this:
...
"distribution": {
"properties": {
"availability": {
"type": "keyword"
}
}
}
...
I want to rank the records with distribution.availability == "ondemand" lower than other records.
I looked in Elasticsearch docs but can't find a way to reduce the scores of this type of records in index-time to appear lower in search results.
How can I achieve this, any pointers to related source would be enough as well.
More Info:
I was completely omitting these ondemand records with help of python client in query-time like this:
from elasticsearch_dsl.query import Q
_query = Q("query_string", query=query_string) & ~Q('match', **{'availability.keyword': 'ondemand'})
Now, I want to include these records but I want to place them lower than other records.
If it is not possible to implement something like this in index-time, please suggest how can I achieve this in query-time with python client.
After applying the suggestion from llermaly, the python client query looks like this:
boosting_query = Q(
"boosting",
positive=Q("match_all"),
negative=Q(
"bool", filter=[Q({"term": {"distribution.availability.keyword": "ondemand"}})]
),
negative_boost=0.5,
)
if query_string:
_query = Q("query_string", query=query_string) & boosting_query
else:
_query = Q() & boosting_query
EDIT2 : elasticsearch-dsl-py version of boosting query
from elasticsearch import Elasticsearch
from elasticsearch_dsl import Search
from elasticsearch_dsl import Q
client = Elasticsearch()
q = Q('boosting', positive=Q("match_all"), negative=Q('bool', filter=[Q({"term": {"test.available.keyword": "ondemand"}})]), negative_boost=0.5)
s = Search(using=client, index="test_parths007").query(q)
response = s.execute()
print(response)
for hit in response:
print(hit.meta.score, hit.test.available)
EDIT : Just read you need to do it on index time.
Elasticsearch deprecated index time boosting on 5.0
https://www.elastic.co/guide/en/elasticsearch/reference/7.11/mapping-boost.html
You can use a Boosting query to achieve that on query time.
Ingest Documents
POST test_parths007/_doc
{
"name": "doc1",
"test": {
"available": "ondemand"
}
}
POST test_parths007/_doc
{
"name": "doc1",
"test": {
"available": "higherscore"
}
}
POST test_parths007/_doc
{
"name": "doc2",
"test": {
"available": "higherscore"
}
}
Query (index time)
POST test_parths007/_search
{
"query": {
"boosting": {
"positive": {
"match_all": {}
},
"negative": {
"term": {
"test.available.keyword": "ondemand"
}
},
"negative_boost": 0.5
}
}
}
Response
{
"took" : 0,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 3,
"relation" : "eq"
},
"max_score" : 1.0,
"hits" : [
{
"_index" : "test_parths007",
"_type" : "_doc",
"_id" : "VMdY7XcB50NMsuQPelRx",
"_score" : 1.0,
"_source" : {
"name" : "doc2",
"test" : {
"available" : "higherscore"
}
}
},
{
"_index" : "test_parths007",
"_type" : "_doc",
"_id" : "Vcda7XcB50NMsuQPiVRB",
"_score" : 1.0,
"_source" : {
"name" : "doc1",
"test" : {
"available" : "higherscore"
}
}
},
{
"_index" : "test_parths007",
"_type" : "_doc",
"_id" : "U8dY7XcB50NMsuQPdlTo",
"_score" : 0.5,
"_source" : {
"name" : "doc1",
"test" : {
"available" : "ondemand"
}
}
}
]
}
}
For more advanced manipulation you can check the Function Score Query
I need to get all objects inside "posts" that have "published: true"
with pymongo. I've tried already so many variants but all I can do:
for elt in db[collection].find({}, {"posts"}):
print(elt)
And it'll show all "posts". I've tried smth like this:
for elt in db[collection].find({}, {"posts", {"published": {"$eq": True}}}):
print(elt)
But it doesn't work. Help, I'm trying for 3 days already =\
What you want to be doing is to use the aggregate $filter like so:
db[collection].aggregate([
{
"$match": { // only fetch documents with such posts
"posts.published": {"$eq": True}
}
},
{
"$project": {
"posts": {
"$filter": {
"input": "$posts",
"as": "post",
"cond": {"$eq": ["$$post.published", True]}
}
}
}
}
])
Note that the currenct structure returned will be:
[
{posts: [post1, post2]},
{posts: [post3, post4]}
]
If you want to retrieve it as a list of posts you'll need to add an $unwind stage to flatten the array.
The query options are quite limited you can do it with $elemMatch (projection) or with the $ operator but both of these return only the first post that matches the condition which is not what you want.
------- EDIT --------
Realizing posts is actually an object and not an array, you'll have to turn the object to an array, iterate over to filter and then restore the structure like so:
db.collection.aggregate([
{
$project: {
"posts": {
"$arrayToObject": {
$filter: {
input: {
"$objectToArray": "$posts"
},
as: "post",
cond: {
$eq: [
"$$post.v.published",
true
]
}
}
}
}
}
}
])
Mongo Playground
What I assumed that your document looks like this,
{
"_id" : ObjectId("5f8570f8afdefd2cfe7473a7"),
"posts" : {
"a" : {
"p" : false,
"name" : "abhishek"
},
"k" : {
"p" : true,
"name" : "jack"
},
"c" : {
"p" : true,
"name" : "abhinav"
}
}}
You can try the following query but the result format will be a bit different, adding that for clarification,
db.getCollection('temp2').aggregate([
{
$project: {
subPost: { $objectToArray: "$posts" }
}
},
{
'$unwind' : '$subPost'
},
{
'$match' : {'subPost.v.p':true}
},
{
'$group': {_id:'$_id', subPosts: { $push: { subPost: "$subPost"} }}
}
])
result format,
{
"_id" : ObjectId("5f8570f8afdefd2cfe7473a7"),
"subPosts" : [
{
"subPost" : {
"k" : "k",
"v" : {
"p" : true,
"name" : "jack"
}
}
},
{
"subPost" : {
"k" : "c",
"v" : {
"p" : true,
"name" : "abhinav"
}
}
}
]
}
I'm am using python-elasticsearch to insert geo data into the engine as below, but what function or method can I use to search for my data? Can you give an example please?
mappings = {
"doc": {
"properties": {
"geo": {
"properties": {
"location": {"type": "geo_point"}
}
}
}
}
}
es.indices.create(index='geodata', body=mappings)
# ...
es_entries['geo'] = {'location':str(data['_longitude_'])+","+str(data['_latitude_'])}
# ...
es.index(index="geodata", doc_type="doc", body=es_entries)
You can use the Geo Distance Query:
{
"query": {
"bool" : {
"must" : {
"match_all" : {}
},
"filter" : {
"geo_distance" : {
"distance" : "10km",
"geo.location" : {
"lat" : 10,
"lon" : -10
}
}
}
}
}
}
You can use both es.search and elasticsearch.helpers.scan, for example:
res = es.search(index='geodata', body= { ... }) # put the above dictionary in the `body`
I am trying to use a custom query DSL to get results using the pyes library. I have query DSL that works when I use the command line
curl -XGET localhost:9200/test_index/_search -d '{
"query": {
"function_score": {
"query": {
"match_all": {}
},
"field_value_factor": {
"field": "starred",
"modifier": "none",
"factor": 2
}
}
},
"aggs" : {
"types" : {
"filters" : {
"filters" : {
"category1" : { "type" : { "value" : "category1"}},
"category2" : { "type" : { "value" : "category2"}},
"category3" : { "type" : { "value" : "category3"}},
"category4": { "type" : { "value" : "category4"}},
"category5" : { "type" : { "value" : "category5"}}
}
},
"aggs": {
"topFoundHits": {
"top_hits": {
"size": 5
}
}
}
}
}
}'
The idea here is to search across many categorized documents for all documents matching a particular string query. Then using aggregations I want to find the top five resulting documents by category. Starred items are boosted so that they show up above other search results.
This works great when I enter the command as listed above directly in terminal but it doesn't work when I try to put it in pyes. I'm not sure what the best way is to do it. The documentation for the pyes library is really confusing for me to translate this totally into pyes objects.
I'm trying to do the following:
query_dsl = self.get_text_index_query_dsl()
resulting_docs = conn.search(query=query_dsl)
(where self.get_test_index_query_dsl returns the query dsl dict above)
Searching as is gives me a:
ElasticSearchException: QueryParsingException[[test_index] No query registered for [query]]; }]
If I remove the parent "query" mapping and try:
query_dsl = {
"function_score": {
"query": {
"match_all": {}
},
"field_value_factor": {
"field": "starred",
"modifier": "none",
"factor": 2
}
},
"aggs" : {
"types" : {
"filters" : {
"filters" : {
"category1" : { "type" : { "value" : "category1"}},
"category2" : { "type" : { "value" : "category2"}},
"category3" : { "type" : { "value" : "category3"}},
"category4": { "type" : { "value" : "category4"}},
"category5" : { "type" : { "value" : "category5"}}
}
},
"aggs": {
"topFoundHits": {
"top_hits": {
"size": 5
}
}
}
}
}
}
This also errors out with: ElasticSearchException: ElasticsearchParseException[Expected field name but got START_OBJECT "aggs"]; }]
These errors in addition to the fact that pyes doesn't seem to have a 'topFoundHits' functionality yet (I think) are holding me up.
Any ideas why this is happening and how to fix it?
Thank you so much!
I got this working using this library where you can just use your regular query dsl JSON syntax : http://elasticsearch-dsl.readthedocs.org/en/latest/.
MongoDB noob here...
So, I'm trying to print out the minimum value score inside a collection that looks like this...
> db.students.find({'_id': 1}).pretty()
{
"_id" : 1,
"name" : "Aurelia Menendez",
"scores" : [
{
"type" : "exam",
"score" : 60.06045071030959
},
{
"type" : "quiz",
"score" : 52.79790691903873
},
{
"type" : "homework",
"score" : 71.76133439165544
},
{
"type" : "homework",
"score" : 34.85718117893772
}
]
}
The incantation I'm using is as such...
db.students.aggregate(
// Initial document match (uses index, if a suitable one is available)
{ $match: {
_id : 1
}},
// Expand the scores array into a stream of documents
{ $unwind: '$scores' },
// Filter to 'homework' scores
{ $match: {
'scores.type': 'homework'
}},
// grab the minimum value score
{ $match: {
'scores.min.score': 1
}}
)
the output i'm getting is this...
{ "result" : [ ], "ok" : 1 }
What am I doing wrong?
You've got the right idea, but in the last step of the aggregation what you want to do is group all the scores by student and find the $min value.
Change the last pipeline operation to:
{ $group: {
_id: "$_id",
minScore: {$min: "$scores.score"}
}}
> db.students.aggregate(
{ $unwind: "$scores" },`
{ $match:{"scores.type":"homework"} },
{ $group: {
_id : "$_id",
maxScore : { $max : "$scores.score"},
minScore: { $min:"$scores.score"}
}
});
how to aggregate on each item in collection in mongoDB