Data structure is like bellow:
{
"_id" : ObjectId("5031e3f0a606e8ef48c7da6b"),
"hitTime" : [ 1345446896, 1345446943, 1345446991 ],
"tag" : "a"
}
I want to get entries that have hitTime>1345446991 so that I can rank the tag popularity.
How do I do this? Or is there other data structures that are convenient to do this incremental count?
Documentation:
That is, when "value" is inspected, if it is an array, each value in the array is checked.
Using the MongoDB documentation, your query should look something like this:
db.collectionName.find({
hitTime : {
$gt : 1345446991
}
});
I am not sure if this works properly, but you might get the idea. =)
Related
I'm new to MongoDB and have to work on a legacy project that I didn't create... and I'm struggling!
I need to reset some documents in one of my collections, based on a particular field value. I have had some success with this so far, but some of the data I need to update is within nested arrays in that document, and I can't work that part out.
Below is an example of one document in the collection:
{
"_id" : ObjectId("1234567890"),
"currentStatus" : "approved",
"itemsInstalled" : [
{
"installDate" : ISODate("2017-04-18T00:00:00.000Z"),
"_id" : ObjectId("1234567890"),
"status" : "approved"
},
{
"installDate" : ISODate("2017-04-18T00:00:00.000Z"),
"_id" : ObjectId("0987654321"),
"status" : "approved"
}
],
"__v" : 5005,
"approvalDate" : ISODate("2017-12-04T10:40:01.580Z"),
"approvedBy" : "automatic"
}
I need to update every document in my collection where the approvedBy field is set to automatic, and leave the others untouched.
For the documents I am updating, I need to remove the approvalDate and approvedBy fields completely, change the currentStatus field to action and change every item in the itemsInstalled array to pending. Everything else can stay as it is.
This is something I would persist with solving myself if I had more time.
Unfortunately, to my knowledge, you can't update multiple array elements. Your best bet is probably to use forEach. You can accomplish what you want with something like this:
db.your_collection.find({
approvedBy: "automatic"
}).forEach(function(doc) {
for(var i = 0; i < doc.itemsInstalled.length; i++) {
doc.itemsInstalled[i].status = "pending";
}
doc.currentStatus = "action";
delete doc.approvedBy;
delete doc.approvalDate;
db.your_collection.update({_id: doc._id}, doc);
});
Using forEach, you can update all of the array elements at once. The downside is that you will be performing multiple update queries, so you should be careful about doing this on particularly large collections or as part of your application logic. Ideally this should be a one-time use scenario.
I have created a collection and added just a name field and tried to apply the following index.
db.names.createIndex({"name":1})
Even after applying the index I see the below result.
db.names.find()
{ "_id" : ObjectId("57d14139eceab001a19f7e82"), "name" : "kkkk" } {
"_id" : ObjectId("57d1413feceab001a19f7e83"), "name" : "aaaa" } {
"_id" : ObjectId("57d14144eceab001a19f7e84"), "name" : "zzzz" } {
"_id" : ObjectId("57d14148eceab001a19f7e85"), "name" : "dddd" } {
"_id" : ObjectId("57d1414ceceab001a19f7e86"), "name" : "rrrrr" }
What am I missing here.
Khans...
the way you built your index is correct however building an ascending index on names wont return the results in ascending order.
if you need results to be ordered by name you have to use
{db.names.find().sort({names:1})}
what happens when you build an index is that when you search for data the Mongo process perform the search behind the scenes in an ordered fashion for faster outcomes.
Please note: if you just want to see output in sorted order. you dont even need an index.
You won't be able to see if an index has been successfully created (unless there is a considerable speed performance) by running a find() command.
Instead, use db.names.getIndexes() to see if the index has been created (it may take some time if you're running the index in the background for it to appear in the index list)
Is there a way to match a value with every array and sub document inside the document in mongodb collection and return the document
{
"_id" : "2000001956",
"trimline1" : "abc",
"trimline2" : "xyz",
"subtitle" : "www",
"image" : {
"large" : 0,
"small" : 0,
"tiled" : 0,
"cropped" : false
},
"Kytrr" : {
"count" : 0,
"assigned" : 0
}
}
for eg if in the above document I am searching for xyz or "ab" or "xy" or "z" or "0" this document should be returned.
I actually have to achieve this at the back end using C# driver but a mongo query would also help greatly.
Please advice.
Thanks
You could probably do this using '$where'
db.mycollection({$where:"JSON.stringify(this).indexOf('xyz')!=-1"})
I'm converting the whole record to a big string and then searching to see if your element is in the resulting string. Probably won't work if your xyz is in the fieldnames!
You can make it iterate through the fields to make a big string and then search it though.
This isn't the most elegant way and will involve a full tablescan. It will be faster if you look through the individual fields!
While Malcolm's answer above would work, when your collection gets large or you have high traffic, you'll see this fall over pretty quickly. This is because of 2 things. First, dropping down to javascript is a big deal and second, this will always be a full table scan because $where can't use an index.
MongoDB 2.6 introduced text indexing which is on by default (it was in beta in 2.4). With it, you can have a full text index on all the fields in the document. The documentation gives the following example where a text index is created for every field and names the index "TextIndex".
db.collection.ensureIndex(
{ "$**": "text" },
{ name: "TextIndex" }
)
Ok there are a couple of things going on here..I have two collections: test and test1. The documents in both collections have an array field (tags and tags1, respectively) that contains some tags. I need to find the intersection of these tags and also fetch the whole document from collection test1 if even a single tag matches.
> db.test.find();
{
"_id" : ObjectId("5166c19b32d001b79b32c72a"),
"tags" : [
"a",
"b",
"c"
]
}
> db.test1.find();
{
"_id" : ObjectId("5166c1c532d001b79b32c72b"),
"tags1" : [
"a",
"b",
"x",
"y"
]
}
> db.test.find().forEach(function(doc){db.test1.find({tags1:{$in:doc.tags}})});
Surprisingly this doesn't return anything. However when I try it with a single document, it works:
> var doc = db.test.findOne();
> db.test1.find({tags1:{$in:doc.tags}});
{ "_id" : ObjectId("5166c1c532d001b79b32c72b"), "tags1" : [ "a", "b", "x", "y" ] }
But this is part of what I need. I need intersection as well. So I tried this:
> db.test1.find({tags1:{$in:doc.tags}},{"tags1.$":1});
{ "_id" : ObjectId("5166c1c532d001b79b32c72b"), "tags1" : [ "a" ] }
But it returned just "a" whereas "a" and "b" both were in tags1. Does positional operator return just the first match? Also, using $in won't exactly give me an intersection..How can I get an intersection (should return "a" and "b") irrespective of which array is compared against the other.
Now say there's an operator that can do this..
> db.test1.find({tags1:{$intersection:doc.tags}},{"tags1.$":1});
{ "_id" : ObjectId("5166c1c532d001b79b32c72b"), "tags1" : [ "a", "b" ] }
My requirement is, I need the entire tags1 array PLUS this intersection, in the same query like this:
> db.test1.find({tags1:{$intersection:doc.tags}},{"tags1":1, "tags1.$":1});
{ "_id" : ObjectId("5166c1c532d001b79b32c72b"), "tags1": [ "a", "b", "x", "y" ],
"tags1" : [ "a", "b" ] }
But this is an invalid json. Is renaming key possible, or this is possible only through aggregation framework (and across different collections?)? I tried the above query with $in. But it behaved as if it totally ignored "tags:1" projection.
PS: I am going to have at least 10k docs in test1 and very few (<10) in test. And this query is in real-time, so I want to avoid mapreduce :)
Thanks for any help!
In newer versions you can use aggregation to accomplish this.
db.test.aggregate(
{
$match: {
tags1: {
$in: doc.tags
}
}
},
{
$project: {
tags1: 1,
intersection: {
$setIntersection: [doc.tags, "$tags1"]
}
}
}
);
As you can see, the match portion is exactly the same as your initial find() query. The project portion generates the result fields. In this case, it selects tags1 from the matching documents and also creates intersection from the input and the matching docs.
Mongo doesn't have any inherent ability to retrieve array intersections. If you really need to use ad-hoc querying get the intersection on the client side.
On the other hand, consider using Map-Reduce and storing it's output as a collection. You can augment the returned objects in the finalize section to add the intersecting tags. Cron MR to run every few seconds. You get the benefit of a permanent collection you can query from on the client side.
If you want to have this in realtime you should consider to move away from Serverside Javascript which is only run with one thread and should be quite slow (single threaded) (this is no longer true for v2.4, http://docs.mongodb.org/manual/core/server-side-javascript/).
The positional operator only returns the first matching/current value. Without knowing the internal implementation, from the point of performance it doesn't even makes sense to look for further matching criteria if the document was already evaluated as match. So I doubt that you can go for this.
I don't know if you need the cartesian product for your search, but I would consider joining your few test one document tags into one and then have some $in search for it on test1, returning all matching documents. On your local machine you could have multiple threads which generate the intersection for your document.
Depending on how frequent your test1 and test collection changes, you're performing this query you might precalculate this information. Which would allow to easily do a query on the field which contains the intersection information.
The document is invalid because you have two fields names tags1
Suppose the collection is like this:
db.mytests.find()
{ "_id" : ObjectId("4fb277b89b8295a790efde44"),
"mylist": [
{ "foo1" :"bar1", "foo2" : "bar2" },
{"foo1" : "bar3", "foo2" : "bar4" }
],
"nonlist" : "nonlistVal" }
I want to remove a document in mylist whose foo1 equal to bar1, after reading mongodb document about updating I used this:
db.mytests.update({},{$pull:{'mylist':{'mylist.$.foo1':'bar1'}}})
but it failed.
To figure out the problem I insert a new array into mytests using this:
db.mytests.update({},{$set:{'anotherList':[1,2,3,4]}})
and then using db.mytests.update({},{$pull:{'anotherList':{$gt:3}}}) to pull the element
4 in array anotherList ,it succeed.
I supposed the problem is with the mylist.$.foo1 ? Can you tell me the right way to remove a document element in a array?
Try changing:
db.mytests.update({},{$pull:{'mylist':{'mylist.$.foo1':'bar1'}}})
to:
db.mytests.update({},{$pull:{'mylist':{'foo1':'bar1'}}})