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Sync Rules are deprecated. For the Sync Streams version of this page, see Storage Version 4.
Storage version 4 is the format the PowerSync Service uses to store the data it syncs to clients. It is the default for MongoDB bucket storage since PowerSync Service v1.27.0. With Sync Rules, storage version 4 provides:
  • Faster sync and faster reprocessing after a deployment.
  • S3 object storage: larger blocks of synced data move from the storage database to S3. This reduces load on the storage database when many clients sync at once or sync large amounts of data. On PowerSync Cloud, PowerSync enables it per instance on request, and plans to enable it on all instances automatically. Self-hosted instances follow the S3 setup instructions.
Incremental reprocessing requires Sync Streams. With Sync Rules, every deployment still reprocesses all data, and clients download all their data again. To use incremental reprocessing, migrate to Sync Streams.

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Switching Storage Versions

Since PowerSync Service v1.27.0, MongoDB bucket storage defaults to version 4. If config.storage_version is unset, the Service uses its default the next time you deploy your Sync Rules. Upgrading the Service alone does not change the storage version of existing Sync Rules. Like any other Sync Rules deployment, this reprocesses all data in the background. Self-hosted instances must use MongoDB bucket storage. Postgres bucket storage is not supported with version 4, so instances with Postgres bucket storage stay on version 2. To use a different version, set storage_version in the config block and deploy. For example, to stay on version 2: