Upgrade Databend-query from 0.8 to 0.9

This topic explains how to migrate metadata when upgrading databend-query from 0.8 to 0.9

Databend-query-0.9 introduces incompatible changes in metadata, these metadata has to be manually migrated. Databend provides a program for this job: databend-meta-upgrade-09, which you can find in a release package or can be built from source.

databend-meta-upgrade-09 upgrades metadata written by databend-query before 0.9 to a databend-query-0.9 compatible format. It loads metadata from a raft-dir and upgrade TableMeta record to 0.9 compatible version and write them back. Both raft-log data and state-machine data will be converted.

Usage

Shut down all databend-meta processes.
Before proceeding, backup your data. See: Backup and resotre metadata.
Download databend-meta-upgrade-09 from Databend release or build it with cargo build --bin databend-meta-upgrade-09
(Optional) To view the current TableMeta version, print all TableMeta records with the following command: It should display a list of TableMeta record. You need to upgrade only if there is a ver that is lower than 24.
```
databend-meta-upgrade-09 --cmd print --raft-dir "<./your/raft-dir/>"
# output:
# TableMeta { ver: 23, ..
```

Upgrade metadata:

databend-meta-upgrade-09 --cmd upgrade --raft-dir "<./your/raft-dir/>"

To assert upgrade has finished successfully, print all TableMeta records that are found in meta dir with the following command: It should display a list of TableMeta record with a ver that is greater or equal 24.
```
databend-meta-upgrade-09 --cmd print --raft-dir "<./your/raft-dir/>"
# output:
# TableMeta { ver: 25, ..
# TableMeta { ver: 25, ..
```