How can I determine what collection a Mongo document belongs to?
I'm using MeteorJS, but even if you don't use this, I'm pretty sure I have access to MongoDB's internal commands so please answer anyways.
Happy to close if this is a duplicate, but I didn't find anything close to this.
There isn't a real short command but to cycle through each collection and query for the field, or fields that uniquely identifies this document. Don't know MeteorJS but if you are looking for just a quick way to get the data to find out and not add a program function you can download RoboMongo. Think of it as SQL Management Studio for MongoDB. If you are looking for a program function to do this then I suggest you make it a jscript function you create inside MongoDB (similar to stored procedures) to do the work and return the results to you when done.
Are you querying the document now and wondering where it is coming from? If so, it should be in the code.
Related
I have a MEAN database application with a number of Mongo collections with hierarchical relationships via ObjectId. A copy of the application works locally offline, and another copy runs on the production server.
The data contain collectively describe rules and content that drive a complex process. These data need to be entered offline so that these processes can be tested before the data go into the production environment.
What I assumed I would be able to easily do is to export selected documents as JSON, then relatively simply import them into the production database. So, the system would have a big "Export" button that would take the current document and all subdocuments and related documents, and export them as a single JSON file. Then, my "Import" button would parse that JSON file on the production server.
So, exporting is no problem. Did that in a couple of hours.
But, I quickly found that when I import a document, its _id field value is not preserved. This breaks relationships, obviously.
I have considered writing parsing routines that preserved these relationships by programmatically setting ObjectIds in parent documents after the child documents have been saved. This will be a huge headache though.
I'm hoping there is either:
a) ... and easy way to import a JSON document with _id fields intact, or ...
b) ... another way to accomplish this entirely that is easier than I am making it.
I appreciate any advice.
There's always got to be someone that doesn't know the answer who complains about the question. The question is clear and the problem is familiar.
Indeed, Mongoose will overwrite any value you provide for _id when you create a document either via the create() method or using the constructor (var thing = new Thing()).
Also, mongoexport/mongoimport will not fill the need to do this programmatically, at least not easily.
If I'm understanding correctly, you want to export a subset of documents, along with any related documents, keeping references intact. Then, you want to import this data into a remote system, again, keeping references intact.
The approach you took would work just fine except it will destroy all references, as you found out.
I've worked on a similar problem and I believe that the best way to do this is to do what it sounds like you wanted to avoid. That is, you'll iterate over your collections and let Mongo generate its _ids as it will. Add your child documents first, then set the references correctly in your parent documents. I really don't think there is a better way that still gives you granular control.
In current version of mongodb you can use db.copyDatabase(). Start current instance of mongodb where you want to copy database and run following command:
db.copyDatabase(fromDB, toDB).
For more options and details refer to db.copyDatabase()
I have two mongo collections. One we can call a template and second is instance. Every time new instance is created, rather large data field is copied from template to instance. Currently the field is retrieved from mongo db template collection in application and then sent back to db as a part of instance collection insert.
Would it be possible to somehow perform this copy on insert directly in mongo db, to avoid sending several megabytes over the network back and forth?
Kadira is reporting 3 seconds lag due to this. And documents are only going to get bigger.
I am using Meteor, but I gather that that should not influence the answer much.
I have done some searching and I can't really find an elegant solution for you. The two ways I can think of doing it are:
1.) Fork a process to run a mongo command to copy your template as your new instance via db.collection.copyTo().
http://eureka.ykyuen.info/2015/02/26/meteor-run-shell-command-at-server-side/
https://docs.mongodb.org/manual/reference/method/db.collection.copyTo/
Or
2.) Attempt to access the raw mongo collection rather than the minimongo collection meteor provides you with so you can use the db.collection.copyTo() functionality supplied by Mongo.
var rawCollection = Collection.rawCollection();
rawCollection.copyTo(newCollection);
Can meteor mongo driver handle $each and $position operators?
I haven't tried accessing the rawCollection to see if copyTo is available, and I also don't know if it will bring it into meteor before writing out the new collection. I'm just throwing this out here as an idea for you; hopefully someone else has a better one.
I have a Mongo database that I did not create or architect, is there a good way to introspect the db or print out what the structure is to start to get a handle on what types of data are being stored, how the data types are nested, etc?
Just query the database by running the following commands in the mongo shell:
use mydb //this switches to the database you want to query
show collections //this command will list all collections in the database
db.collectionName.find().pretty() //this will show all documents in the database in a readable format; do the same for each collection in the database
You should then be able to examine the document structure.
There is actually a tool to help you out here called Variety:
http://blog.mongodb.org/post/21923016898/meet-variety-a-schema-analyzer-for-mongodb
You can view the Github repo for it here: https://github.com/variety/variety
I should probably warn you that:
It uses MR to accomplish its tasks
It uses certain other queries that could bring a production set-up to a near halt in terms of performance.
As such I recommend you run this on a development server or a hidden node of a replica or something.
Depending on the size and depth of your documents it may take a very long time to understand the rough structure of your database through this but it will eventually give one.
This will print name and its type
var schematodo = db.collection_name.findOne()
for (var key in schematodo) { print (key, typeof key) ; }
I would recommend limiting the result set rather than issuing an unrestricted find command.
use mydb
db.collectionName.find().limit(10)
var z = db.collectionName.find().limit(10)
Object.keys(z[0])
Object.keys(z[1])
This will help you being to understand your database structure or lack thereof.
This is an open-source tool that I, along with my friend, have created - https://pypi.python.org/pypi/mongoschema/
It is a Python library with a pretty simple usage. You can try it out (even contribute).
One option is to use the Mongoeye. It is open-source tool similar to the Variety.
The difference is that Mongoeye is a stand-alone program (Mongo Shell is not required) and has more features (histograms, most frequent values, etc.).
https://github.com/mongoeye/mongoeye
Few days ago I found GUI client MongoDB Compass with some nice visualizations. See the product overview. It comes directly from the mongodb people and according to their doc:
MongoDB Compass is designed to allow users to easily analyze and understand the contents of their data collections within MongoDB...
You may've asked about validation schema. Here's the answer how to get it:
How to retrieve MongoDb collection validator rules?
Use Mongo Compass
which does a sample as explained here
Which does a random sample of 1000 documents to get you the schema - it could miss something but it's the only rational option if you database is several GBs.
Visualisation
The schema then can be exported as JSON
Documentation
You can use MongoDB's tool mongodump. On running it, a dump folder is created in the directory from which you executed mongodump. In that folder, there are multiple folders that correspond to the databases in MongDB, and there are subfolders that correspond to the collections, and files that correspond to the documents.
This method is the best I know of, as you can also make out the schema of empty collections.
I am really new to the programming but I am studying it. I have one problem which I don't know how to solve.
I have collection of docs in mongoDB and I'm using Elasticsearch to query the fields. The problem is I want to store the output of search back in mongoDB but in different DB. I know that I have to create temporary DB which has to be updated with every search result. But how to do this? Or give me documentation to read so I could learn it. I will really appreciate your help!
Mongo does not natively support "temp" collections.
A typical thing to do here is to not actually write the entire results output to another DB since that would be utterly pointless since Elasticsearch does its own caching as such you don't need any layer over the top.
As well, due to IO concerns it is normally a bad idea to write say a result set of 10k records to Mongo or another DB.
There is a feature request for what you talk of: https://jira.mongodb.org/browse/SERVER-3215 but no planning as of yet.
Example
You could have a table of results.
Within this table you would have a doc that looks like:
{keywords: ['bok', 'mongodb']}
Each time you search and scroll through each result item you would write a row to this table populating the keywords field with keywords from that search result. This would be per search result per search result list per search. It would probably be best to just stream each search result to MongoDB as they come in. I have never programmed Python (though I wish to learn) so an example in pseudo:
var elastic_results = [{'elasticresult'}];
foreach(elastic_results as result){
//split down the phrases in this result and make a keywords array
db.results_collection.insert(array_formed_from_splitting_down_result); // Lets just lazy insert no need for batch or trying to shrink the amount of data to one go or whatever, lets just stream it in.
}
So as you go along your results you basically just mass insert as fast a possible create a sort of "stream" of input to MongoDB. It can do this quite well.
This should then give you a shardable list of words and language verbs to process things like MRs on and stuff to aggregate statistics about them.
Without knowing more and more about your scenario this is pretty much my best answer.
This does not use the temp table concept but instead makes your data permanent which is fine by the sounds of it since you wish to use Mongo as a storage engine for further tasks.
Actually there is MongoDB river plugin to work with Elasticsearch...
db.your_table.find().forEach(function(doc) { b.another_table.insert(doc); } );
Bear with me as I'm pretty new to MongoDB and mongoose has been my only interaction with it. So apologize ahead of time if I'm not properly separating the two technologies or understanding either.
I have a collection that is basically a log. Each log item is the result of a status check on a specific server that I have in my system. When I delete a server I'd like to also remove all the associated log entries. Whats the most efficient way to do this? I know I can find all the log items with a specific server id then iterate through each and remove it but that seems really inefficient. I've read through most of the mongo documentation and it looks like findAndModify is the best way to do this but I can't figure out syntax for this with mongoose. Any chance someone could help me out?
I'm using the latest version on mongoose at the moment, 1.7.2
Maybe I'm missing something here, but why not just do
db.logs.remove({serverid: deletedServerId})
?