# From Cosmos DB to MongoDB

### Step 1: Download dsync

{% hint style="info" %}
Working on a large-scale production environment? Use our horizontally scalable [Enterprise offering.](https://docs.adiom.io/enterprise/scalable-deployment)
{% endhint %}

Use Docker (`markadiom/dsync`) or download the latest release from the [GitHub Releases](https://github.com/adiom-data/dsync/releases/latest) page. Note that on Mac devices you may need to configure a security exception to execute the binary by following [these steps](https://support.apple.com/en-ca/guide/mac-help/mh40616/mac).

Alternatively, you can build dsync from the source code.

```bash
git clone https://github.com/adiom-data/dsync.git
cd dsync
go build
```

{% hint style="info" %}
You can use Homebrew to easily install Dsync on your Mac:

```
brew install adiom-data/homebrew-tap/dsync
```

{% endhint %}

***

### Step 2: Prepare the destination MongoDB instance

{% hint style="warning" %}
If you already have the desired destination MongoDB instance up and running, you can skip this step.
{% endhint %}

1. Install [MongoDB](https://www.mongodb.com/docs/manual/administration/install-community/)
2. Start a local MongoDB instance:

```bash
mkdir ~/temp
cd ~/temp
mkdir data_d
mongod --dbpath data_d --logpath mongod_d.log --fork --port 27017
```

***

### Step 3: Start dsync

```bash
# You can use our publicly accessible (read-only) Cosmos DB instance
export COSMOS_DEMO=$(echo bW9uZ29kYjovL2Nvc21vc2RiLWRlbW8taW5zdGFuY2U6SkhiRWpRb2JkWm03YWJEcFp2UzZrWHpBMDRXNTBJd2V4QmlQYnVJWFQ2TElmNkhsV2V4YWphQzhkd042REJ2YVh6ajBnclFrdkwzY0FDRGJONjdxZWc9PUBjb3Ntb3NkYi1kZW1vLWluc3RhbmNlLm1vbmdvLmNvc21vcy5henVyZS5jb206MTAyNTUvP3NzbD10cnVlJnJlcGxpY2FTZXQ9Z2xvYmFsZGImcmV0cnl3cml0ZXM9ZmFsc2UmbWF4SWRsZVRpbWVNUz0xMjAwMDAmYXBwTmFtZT1AY29zbW9zZGItZGVtby1pbnN0YW5jZUA= | base64 --decode)

# Feel free to use your own MongoDB connection string
export MDB_DEST='mongodb://localhost:27017' 

./dsync --progress --logfile dsync.log $COSMOS_DEMO $MDB_DEST
```

Now Dsync should be running! Feel free to interrupt the sync process (via Ctrl+C) it once the initial sync is done. The demo database has a few million records and the resources are shared - allow 5-10 minutes for the process to complete.

***

### Step 4: Check the data

```bash
mongosh $MDB_DEST
```

Congratulations! You should be able to access the 'odc' database and see the collections in it that were migrated from the Cosmos DB.