# Upgrade Procedure

This document describes how to upgrade your existing installation of the BanyanDB database.

## Server and File Versioning

BanyanDB uses a separate version for the server and the file format. The server version is the version of the BanyanDB server binary, and the file version is the version of the data files stored on the disk.

You can use "banyand liaison/data/standalone -v" to check the server version. The file version is stored in "metadata" file laid in each ["segment"](../concept/tsdb.md#segment) folder.

The server will check the file version when it starts. If the file version is not compatible with the supported version list in the server, the server will refuse to start. Please check the [CHANGELOG.md](https://github.com/apache/skywalking-banyandb/tree/master/CHANGES.md) to ensure that the new version is compatible with the existing data files.

BanyanDB upgrade procedure is a rolling upgrade. You can upgrade the BanyanDB cluster without downtime. But you need to follow the instructions carefully to avoid any data loss:

- Perform the upgrades consecutively. You cannot skip versions.
- You must keep the all nodes with the same version. Do not mix versions in the same cluster.

All node roles (liaison and data) can be upgraded using the same procedure.

## Upgrade a Single Node

- Stop the server by sending a `SIGINT` or `SIGTERM` signal to the process.
- Wait for the server to stop gracefully.
- Replace the binary with the new version.
- Start the server with the same configuration.

## Rolling Strategy to Upgrade a Cluster

Before upgrading the cluster, you should check CHANGELOG.md](https://github.com/apache/skywalking-banyandb/tree/master/CHANGES.md) to ensure that there are no breaking changes in the new version.

- Upgrade the nodes one by one.
- Wait for the node to join the cluster and become healthy before upgrading the next node.
- Upgrade "data" nodes first, then "liaison" nodes.
- After upgrading all nodes, the cluster will be running the new version.

> **Exception — upgrading to 0.11 or later.** The vectorized query paths change the
> liaison<->data wire format, and a data node must never have a vectorized path enabled
> that the liaison it answers cannot decode. For 0.11 the order is **reversed**: upgrade
> "liaison" nodes first, then "data" nodes. See [Vectorized query paths enabled by default](#vectorized-query-paths-enabled-by-default-breaking-for-rolling-upgrades).

To ensure this strategy works, you should have a minimum of one node for each role of node in the cluster. For example, if you have a 2-node cluster, you should have at least one "liaison" and one "data" node.

The cluster should also have enough capacity to handle the load when one node is down for upgrade.

## Minimum Downtime Strategy to Upgrade a Cluster

If the new version has breaking changes, you can use the following strategy to upgrade the cluster with minimum downtime:

- Stop "liaison" nodes gracefully in a parallel manner.
- Stop "data" gracefully.
- Start the new version of "data" nodes.
- Start the new version of "liaison" nodes.

The data ingestion and retrieval will be stopped during the upgrade process. The downtime will be the sum of the time taken to stop and start the nodes. All these steps should be running in parallel to minimize the downtime.

If you don't have enough resource to perform a rolling upgrade or you have a large cluster with many nodes, you can use the minimum downtime strategy.

## Upgrading to 0.11

This section describes breaking changes and important behavioral changes when upgrading to BanyanDB 0.11.0.

### Vectorized query paths enabled by default (breaking for rolling upgrades)

The vectorized **stream** and **trace** query paths are now enabled by default, joining **measure** (default-on since 0.10). `--stream-vectorized-enabled`, `--trace-vectorized-enabled` and `--measure-vectorized-enabled` all default to `true`.

**This changes the required rolling-upgrade order. Upgrade "liaison" nodes BEFORE "data" nodes.**

The reason is that each flag selects the liaison<->data wire format as well as the query engine. A flag-on distributed **data** node emits a native columnar frame instead of protobuf. Liaison nodes on 0.11 accept both — they dispatch per message on the frame's leading magic byte and fall back to protobuf — but a liaison still running an older binary has **no frame decoder at all** and will fail to deserialize the response.

The two orders behave differently:

| Upgrade order | Result |
| --- | --- |
| Liaison first, then data | **Safe.** New liaisons decode both frames and protobuf; old data nodes keep sending protobuf until upgraded. |
| Data first, then liaison | **Queries fail** for the duration of the rollout. New data nodes emit frames that old liaisons cannot decode. |

This is the opposite of the general rolling strategy documented above, which applies to all other upgrades.

If you cannot control node ordering, either use the [Minimum Downtime Strategy](#minimum-downtime-strategy-to-upgrade-a-cluster), or start the new data nodes with the vectorized paths explicitly disabled and enable them after every liaison is upgraded:

```shell
banyand data \
  --stream-vectorized-enabled=false \
  --trace-vectorized-enabled=false \
  --measure-vectorized-enabled=false
```

Standalone deployments are unaffected: the frame is only emitted on a distributed data node, so a standalone server always uses the protobuf path regardless of the flag.

**Rollback.** Pass `--stream-vectorized-enabled=false` / `--trace-vectorized-enabled=false` / `--measure-vectorized-enabled=false` on the standalone or data-node command line and restart. The row path and the protobuf wire format resume immediately; no data migration is involved, because the flags affect only the query and wire paths, never the on-disk format.

## Upgrading to 0.10

This section describes breaking changes and important behavioral changes when upgrading to BanyanDB 0.10.0.

### Property on-disk path change (breaking)

The property data storage path structure has changed:

- **Before**: `<data-dir>/property/data/shard-<id>/...`
- **After**: `<data-dir>/property/data/<group>/shard-<id>/...`

The new path includes the `<group>` directory under `property/data/`. Existing data at the old path layout will **not** be automatically migrated. Plan a data migration strategy or accept that existing property data at the old path will not be accessible after upgrade.

### Node discovery default changed (breaking)

The default node discovery mode changed from `etcd` to `none`. Cluster deployments **must** explicitly set `--node-discovery-mode=etcd` (or another supported mode such as `dns` or `file`) on each node to maintain the previous behavior. Without this flag, the cluster nodes will not discover each other after the upgrade. For configuration details, see [Node Discovery](../operation/node-discovery.md).

Standalone deployments are unaffected since they do not use node discovery.

### Windows binaries no longer shipped (breaking)

Release binaries and Docker images no longer include Windows builds. Users requiring Windows must build from source.

### Bloom filters removed for dictionary-encoded tags

Queries on dictionary-encoded tags no longer use Bloom filters. The engine now uses a more efficient dictionary-based filter for tag filtering. This may change query performance characteristics. See [TSDB documentation](../concept/tsdb.md) for storage format details.

### Criteria tags no longer required in projection

Tags used in `WHERE` conditions no longer need to be included in the `SELECT` projection. This is a backward-compatible improvement. Existing queries continue to work, and new queries can omit criteria tags from projections. See [BydbQL](../interacting/bydbql.md) for details.

### Property repair activated by default

The property background repair mechanism is now enabled by default. This automatically repairs inconsistent property data. To disable or tune this behavior, use flags such as `--property-repair-enabled` and `--property-repair-cron`. See [Property Repair](../operation/property-repair.md) for full configuration options.

## Rollback

If you encounter any issues during the upgrade process, you can rollback to the previous version by following the same procedure as the upgrade process. If file format is backward compatible, you can rollback to the previous version without any data loss. Please check the [CHANGELOG.md](https://github.com/apache/skywalking-banyandb/tree/master/CHANGES.md) to ensure that old version is compatible with the new data files.
