landing_page/qdrant-landing/content/documentation/edge/edge-data-synchronization-patterns.md

title, short_description, description, weight, partition

title	short_description	description	weight	partition
Data Synchronization Patterns	Sync Qdrant Edge Shards with server collections using snapshots, partial updates, and dual-write patterns for offline-first apps.	Synchronize Qdrant Edge Shards with server collections through snapshots, partial updates, and dual-write patterns for offline-first edge applications.	20	develop

Data Synchronization Patterns

This page describes patterns for synchronizing data between Qdrant Edge Shards and Qdrant server collections. For a practical end-to-end guide on implementing these patterns, refer to the Qdrant Edge Synchronization Guide.

Initialize Edge Shard from Existing Qdrant Collection

Instead of starting with an empty Edge Shard, you may want to initialize it with pre-existing data from a collection on a Qdrant server. You can achieve this by restoring a snapshot of a shard in the server-side collection.

When creating a snapshot for synchronization, specify the applicable server-side shard ID in the snapshot URL. This allows for a single collection to serve multiple independent users or devices, each with its own Edge Shard. Read more about Qdrant's sharding strategy in the Tiered Multitenancy Documentation.

First, craft a snapshot URL and use the URL to download the snapshot to the local disk. Next, use the snapshot to initialize a new Edge Shard.

{{< code-snippet path="/documentation/headless/snippets/edge/synchronization-patterns/" block="restore-snapshot" >}}

Note that this example uses shard ID 0.

This code first downloads the snapshot to a temporary directory. Next, EdgeShard.unpack_snapshot unpacks the downloaded snapshot into the data directory, and an EdgeShard is initialized using the unpacked data and configuration.

The edge_shard will use the same configuration and the same file structure as the source collection from which the snapshot was created, including vector and payload indexes.

Update Qdrant Edge with Server-Side Changes

To keep an Edge Shard updated with new data from a server collection, you can periodically download and apply a snapshot. Restoring a full snapshot every time would create unnecessary overhead. Instead, you can use partial snapshots to restore changes since the last snapshot. A partial snapshot contains only those segments that have changed, based on the Edge Shard's manifest that describes all its segments and metadata.

{{< code-snippet path="/documentation/headless/snippets/edge/synchronization-patterns/" block="update-from-snapshot" >}}

Update a Server Collection from an Edge Shard

To synchronize data from an Edge Shard to a server collection, implement a dual-write mechanism in your application. When you add or update a point in the Edge Shard, simultaneously store it in a server collection using the Qdrant client.

Instead of writing to the server collection directly, you may want to set up a background job or a message queue that handles the synchronization asynchronously. The application may not always have a stable internet connection, so queuing updates ensures that data is eventually synchronized when connectivity is restored.

First, initialize:

• an Edge Shard from scratch or from server-side snapshot
• a Qdrant server connection.

Details

Initialize an Edge Shard: {{< code-snippet path="/documentation/headless/snippets/edge/synchronization-patterns/" block="initialize-edge-shard" >}}

Initialize a Qdrant client connection to the server and create the target collection if it does not exist:

{{< code-snippet path="/documentation/headless/snippets/edge/synchronization-patterns/" block="initialize-server-client" >}}

Next, instantiate the queue that will hold the points that need to be synchronized with the server:

{{< code-snippet path="/documentation/headless/snippets/edge/synchronization-patterns/" block="create-upload-queue" >}}

When adding or updating points in the Edge Shard, also enqueue the point for synchronization with the server.

{{< code-snippet path="/documentation/headless/snippets/edge/synchronization-patterns/" block="upsert-point" >}}

A background worker can process the upload queue and synchronize points with the server collection. This example uploads points in batches of up to 10 points at a time:

{{< code-snippet path="/documentation/headless/snippets/edge/synchronization-patterns/" block="process-upload-queue" >}}

Make sure to properly handle errors and retries in case of network issues or server unavailability.