Mongo DB Administration

Access mongo CLI

$> mongo

Show databases

show dbs;

Show Collections

show collections;

Filter Unique Values

Filter unique values (only the values) from a column (first you must «use db», only change «collection» and «column» do not change the db prefix)

> db['collection'].distinct('COLUMN')

Filter Unique Values on duplicated elements and show all the fields of the document

I had to filter an specific field, for example:

computer:1, mac: aa:bb:cc:dd:ee
computer:2, mac: a1:b1:c1:d1:e1
computer:1, mac: aa:bb:cc:dd:ee
computer:2, mac: a1:b1:c1:d1:e1
computer3,  mac: a2:b2:c2:d2:e2

(Yes, the same data is inserted over and over again with certain variations on other fields, but each MACAddress is unique).

And I would like to return:

computer:1, mac: aa:bb:cc:dd:ee
computer:2, mac: a1:b1:c1:d1:e1
computer3,  mac: a2:b2:c2:d2:e2

So,

Filter the unique values using .unique()

1. do a (for) loop over that values

def displayInventoryNotebooksByMAC():
    """
    Este metodo lista toda la informacion de las notebooks filtrando por unica MAC Address 
    posteriormente agrega los datos en una nueva coleccion para inventariado
    """
    uniqueNotebook=[]
    notebooksByMAC = displayTotalNotebooksByMAC()

    # En esta primera etapa, mostraremos notebooks unicas por MAC
    for mac in notebooksByMAC:
        uniqueNotebooks = collection.find_one( {'MACADD': mac } )
        uniqueNotebook.append(uniqueNotebooks)
        # Ahora, agregamos esos resultados a la nueva coleccion que servira de inventario
        # Buscamos la MAC antes de agregar pues no debemos sumar duplicados
        if invCollection.find( { 'MACADD':mac } ).count() == 0 :
            invCollection.insert(uniqueNotebooks)

    return uniqueNotebook

Remove fields from all documents

db.example.update({}, {$unset: {words:1}}, false, true);

Backup mongodb

This is the Recommended method by mongo

mortiz@tinylab:/var/$ mongodump --host localhost:27017

If you receive this error, be sure you are in a path with write access:

2019-06-03T10:59:27.532-0300	Failed: error dumping metadata: error creating directory for metadata file dump/myProject: mkdir dump: permission denied

So a dump folder will be created with all the binary data of your mongoDB:

drwxr-xr-x 4 mortiz mortiz      4096 Jun  3 10:59 dump
mortiz@tinylab:~$ cd dump/
mortiz@tinylab:~/dump$ ls -ltr
total 8
drwxr-xr-x 2 mortiz mortiz 4096 Jun  3 10:59 myProject
drwxr-xr-x 2 mortiz mortiz 4096 Jun  3 10:59 admin
mortiz@tinylab:~/dump$ cd myProject/
mortiz@tinylab:~/dump/myProject$ ls -ltr
total 900
-rw-r--r-- 1 mortiz mortiz    138 Jun  3 10:59 myProjectLaptops.metadata.json
-rw-r--r-- 1 mortiz mortiz    133 Jun  3 10:59 Desktops.metadata.json
-rw-r--r-- 1 mortiz mortiz 514625 Jun  3 10:59 myProjectLaptops.bson
-rw-r--r-- 1 mortiz mortiz 395518 Jun  3 10:59 Desktops.bson
mortiz@tinylab:~/dump/myProject$ cat Desktops.bson

Restore mongodb

After using mongodump you can restore easily by using mongorestore and the directory name where is your backup, here «dump» is the default name of the directory after executing mongo restore:

root@myserer:~# mongorestore dump
2019-06-03T10:37:11.057-0400	building a list of dbs and collections to restore from dump dir
2019-06-03T10:37:11.058-0400	reading metadata for myproject.myprojectlaptops from dump/myproject/myprojectlaptops.metadata.json
2019-06-03T10:37:11.089-0400	restoring myproject.myprojectlaptops from dump/myproject/myprojectlaptops.bson
2019-06-03T10:37:11.090-0400	reading metadata for myproject.Desktops from dump/myproject/Desktops.metadata.json
2019-06-03T10:37:11.110-0400	restoring myproject.Desktops from dump/myproject/Desktops.bson
2019-06-03T10:37:11.119-0400	restoring indexes for collection myproject.myprojectlaptops from metadata
2019-06-03T10:37:11.119-0400	finished restoring myproject.myprojectlaptops (1042 documents)
2019-06-03T10:37:11.126-0400	restoring indexes for collection myproject.Desktops from metadata
2019-06-03T10:37:11.127-0400	finished restoring myproject.Desktops (1213 documents)
2019-06-03T10:37:11.127-0400	done

Delete documents with empty fields

This will delete ALL documents with that empty/null field:

db.collection.deleteMany( { "FIELD" : null } )

But sometimes isn’t null just «empty», so:

db.collection.deleteMany( { "FIELD" : "" } )

Trim specific field in all documents of a collection

> db.collection.update( {}, [{ $set: { YOURFIELD: { $trim: { input: "$YOURFIELD" } } } }],  { multi: true } )
WriteResult({ "nMatched" : 32031, "nUpserted" : 0, "nModified" : 9691 })