I am on windows platform. I have a shell script which delete the whole database when cronjob cal this file.
File is
delete.sh
#!/usr/bin/env mongo
mongo 127.0.0.1:27021/test --eval "db.dropDatabase()"
Let's say I have a collection named as "Doctor" Now I don't want to delete that table.
Any idea how to acheive this.
can we use --excludeCollection here???
There is no such flag. Dropping database means dropping the whole database. If you need at least one collection to remain you need to keep the database. Collections don't exists without a database.
What you can do is to drop collections instead. Use db.getCollectionNames and drop them one by one excluding the ones you want to keep.
E.g. with filter:
mongo 127.0.0.1:27021/test --eval "db.getCollectionNames().filter(c=>!['Doctor'].includes(c)).forEach(c=>db.getCollection(c).drop())"
Or using getCollectionInfos with query filter:
mongo 127.0.0.1:27021/test --eval "db.getCollectionInfos({name:{$nin: ['Doctor']}}).forEach(({name})=>db.getCollection(name).drop())"
You may need to escape the dollar sign in $nin. I can't recall how shell scripts work on windows.
Related
As I was importing a new json file to my mongodb collection I've accidentally use just one '-' instead of 2. Eg.:
mongoimport --host=127.0.0.1 --db=dataBaseName -collection=people --file=importFile.json
I believe that due to the lack of the second '-', now I'm stuck with the following results when I type show collections:
people
ollection=people
I can't access, drop or interact with the second one. Apart from droping the database and starting over, is there a way around this issue?
You can rename the collection like:
> use YourDatabase
// Might wanna drop people collection first
> db.getCollection("ollection=people").renameCollection("people")
Hope This helps!
I am using MongoDB at mLab. I have multiple collections - 1 main and other supporting. Therefore, the main collection consists of IDs pointing to supporting collections. I would like to export the actual data from the main collection to a CSV file. So I need to populate the data first and then export the result.
I see I can export collections individually but then the data are not populated. I suppose I should use bash script to do this but I do not know how.
Could you point me the right direction or suggest a way to do this?
Thank you!
Using the mongo shell will be the better idea in your case, as per the official documents below is the steps to write the bash script to read the data from mongo collection in bash shell scripts:
Simple example to get the data count from a collection with updated date time with greater than 10 days.
DATE2=$(date -d '10 days ago' "+%Y-%m-%dT%H:%M:%S.%3NZ");
counter = $(mongo --quiet dbName --eval 'db.dbCollection.find({"updatedAt":{"$gt":new ISODate("'$DATE'")}}).count()')
echo counter;
Or you can get the list of data and iterate over it to populate it as per your requirements.
For more on mongo shell query click here
I'm beginner with mongoDB. i want to know is there any way to load predefined schema to mongoDB? ( for example like cassandra that use .cql file for this purpose)
If there is, please intruduce some document about structure of that file and way for restoring.
If there is not, how i can create an index only one time when I create a collection. I think it is wrong if i create index every time I call insert method or run my program.
p.s: I have a multi-threaded program that every thread insert and update my mongo collection. I want to create index only one time.
Thanks.
To create an index on a collection you need to use ensureIndex command. You need to only call it once to create an index on a collection.
If you call ensureIndex repeatedly with the same arguments, only the first call will create an index, all subsequent calls will have no effect.
So if you know what indexes you're going to use for your database, you can create a script that will call that command.
An example insert_index.js file that creates 2 indexes for collA and collB collections:
db.collA.ensureIndex({ a : 1});
db.collB.ensureIndex({ b : -1});
You can call it from a shell like this:
mongo --quiet localhost/dbName insert_index.js
This will create those indexes on a database named dbName on your localhost. It's worth noticing that if your database and/or collections are not yet created, this will create both the database and the collections for which you're adding the indexes.
Edit
To clarify a little bit. MongoDB is schemaless so you can't restore it's schema.
You can only create indexes and collections (by using createCollection helper).
MongoDB is basically schemaless so there is no definition of a schema or namespaces to be restored.
In the case of indexes, these can be created at any time. There does not need to be a collection present or even the required fields for the index as this will all be sorted out as the collections are created and when documents are inserted that matches the defined fields.
Commands to create an index are generally the same with each implementation language, for example:
db.collection.ensureIndex({ a: 1, b: -1 })
Will define the index on the target collection in the target database that will reference field "a" and field "b", the latter in descending order. This will happen even if the collection or even the database does not exist as yet, or in fact will establish a blank namespace in that case.
Subsequent calls to the same index creation method do not actually re-create the index. Where the same index is specified to one that already exists it is effectively skipped as a "no-operation".
As such, you can simply feed all your required index creation statements at application startup and anything that is not already present will be created. Anything that already exists will be left alone.
How can I drop a MongoDB collection in Erlang using the mongodb-erlang driver (https://github.com/mongodb/mongodb-erlang)?
I didn't find anything in the docs: http://api.mongodb.org/erlang/mongodb/
I'm writing tests that create collections with different names and I want to drop them when the tests are finished. I can delete all the documents in a collection, but I want to drop the collection itself.
Use the mongo_query:command/3 function and the document form of the drop command:
1> mongo_query:command({Db, Conn}, {drop, 'foo.bar.baz'}, false).
{nIndexesWas,1.0,msg,<<"indexes dropped for collection">>,
ns,<<"foo.bar.baz">>,
ok,1.0}
Takes a regular connection, not a replset connection.
mongo_query:command/3 function:
http://api.mongodb.org/erlang/mongodb/mongo_query.html#command-3
Document form of MongoDB drop command function:
http://docs.mongodb.org/manual/reference/command/drop/#dbcmd.drop
What I want:
I have a master collection of products, I then want to filter them and put them in a separate collection.
db.masterproducts.find({category:"scuba gear"}).copyTo(db.newcollection)
Of course, I realise the 'copyTo' does not exist.
I thought I could do it with MapReduce as results are created in a new collection using the new 'out' parameter in v1.8; however this new collection is not a subset of my original collection. Or can it be if I use MapReduce correctly?
To get around it I am currently doing this:
Step 1:
/usr/local/mongodb/bin/mongodump --db database --collection masterproducts -q '{category:"scuba gear"}'
Step 2:
/usr/local/mongodb/bin/mongorestore -d database -c newcollection --drop packages.bson
My 2 step method just seems rather inefficient!
Any help greatly appreciated.
Thanks
Bob
You can iterate through your query result and save each item like this:
db.oldCollection.find(query).forEach(function(x){db.newCollection.save(x);})
You can create small server side javascript (like this one, just add filtering you want) and execute it using eval
You can use dump/restore in the way you described above
Copy collection command shoud be in mongodb soon (will be done in votes order)! See jira feature.
You should be able to create a subset with mapreduce (using 'out'). The problem is mapreduce has a special output format so your documents are going to be transformed (there is a JIRA ticket to add support for another format, but I can not find it at the moment). It is also going to be very inefficent :/
Copying a cursor to a collection makes a lot of sense, I suggest creating a ticket for this.
there is also toArray() method which can be used:
//create new collection
db.creatCollection("resultCollection")
// now query for type="foo" and insert the results into new collection
db.resultCollection.insert( (db.orginialCollection.find({type:'foo'}).toArray())