Compatibility
This guideline will introduce how to investigate and manage the compatibility:
- between databend-query and databend-meta.
- between different versions of databend-meta.
Compatibility between databend-query and databend-meta
Identifying the versions
-
To find out the build version of databend-query and its compatible databend-meta version:
databend-query --cmd ver
# output:
version: 0.7.61-nightly
min-compatible-metasrv-version: 0.7.59Which means this build of databend-query(
0.7.61-nightly
) can talk to a databend-meta of at least version0.7.59
, inclusive. -
To find out the build version of databend-meta and its compatible databend-query version:
databend-meta --cmd ver
# output:
version: 0.7.61-nightly
min-compatible-client-version: 0.7.57Which means this build of databend-meta(
0.7.61-nightly
) can talk to a databend-query of at least version0.7.57
, inclusive.
Maintaining compatibility
A databend cluster has to be deployed with compatible versions of databend-query and databend-meta. A databend-query and databend-meta are compatible iff the following statements hold:
databend-query.version >= databend-meta.min-compatible-client-version
databend-bend.version >= databend-query.min-compatible-metasrv-version
If incompatible versions are deployed, an error InvalidArgument
will occur when databend-query tries to connect to databend-meta,
which can be found in databend-query log.
Then databend-query will stop working.
Compatibility verification protocol
Compatibility will be checked when a connection is established between meta-client(databend-query) and databend-meta, in a handshake
RPC.
The client C
(databend-query) and the server S
(databend-meta) maintains two semantic-versions:
C
maintains its own semver(C.ver
) and the minimal compatibleS
semver(C.min_srv_ver
).S
maintains its own semver(S.ver
) and the minimal compatibleS
semver(S.min_cli_ver
).
When handshaking:
C
sends its verC.ver
toS
,- When
S
receives handshake request,S
asserts thatC.ver >= S.min_cli_ver
. - Then
S
replies handshake-reply with itsS.ver
. - When
C
receives the reply,C
asserts thatS.ver >= C.min_srv_ver
.
Handshake succeeds if both of these two assertions hold.
E.g.:
S: (ver=3, min_cli_ver=1)
is compatible withC: (ver=3, min_srv_ver=2)
.S: (ver=4, min_cli_ver=4)
is NOT compatible withC: (ver=3, min_srv_ver=2)
. Because althoughS.ver(4) >= C.min_srv_ver(3)
holds, butC.ver(3) >= S.min_cli_ver(4)
does not hold.
C.ver: 1 3 4
C --------+-------------+------+------------>
^ .------' ^
| | |
'-------------. |
| | |
v | |
S ---------------+------+------+------------>
S.ver: 2 3 4
Compatibility status
The following is an illustration of the latest query-meta compatibility:
Meta\Query | [0.9.41, 1.1.34) | [1.1.34, 1.2.287) | [1.2.287, 1.2.361) | [1.2.361, +∞) |
---|---|---|---|---|
[0.8.30, 0.8.35) | ❌ | ❌ | ❌ | ❌ |
[0.8.35, 0.9.23) | ✅ | ❌ | ❌ | ❌ |
[0.9.23, 0.9.42) | ✅ | ❌ | ❌ | ❌ |
[0.9.42, 1.1.32) | ✅ | ❌ | ❌ | ❌ |
[1.1.32, 1.2.63) | ✅ | ✅ | ❌ | ❌ |
[1.2.63, 1.2.226) | ✅ | ✅ | ❌ | ❌ |
[1.2.226, 1.2.258) | ✅ | ✅ | ✅ | ❌ |
[1.2.258, +∞) | ✅ | ✅ | ✅ | ✅ |
History versions that are not included in the above chart:
- Query
[0.7.59, 0.8.80)
is compatible with Meta[0.8.30, 0.9.23)
. - Query
[0.8.80, 0.9.41)
is compatible with Meta[0.8.35, 0.9.42)
.
Compatibility between databend-query
Query version | Backward compatible with |
---|---|
[-∞, 1.2.307) | [-∞, 1.2.311) |
[1.2.307, 1.2.311) | [-∞, 1.2.311) |
[1.2.311, +∞) | [1.2.307, +∞) |
Since 1.2.307, support deseriazlie Role info with pb and json but only support serialize Role info to json.
Since 1.2.311, only support seriazlie Role info to pb.
Prevents the query node that is not successfully upgraded from reading data due to operations on the role during rolling upgrade. You are advised to upgrade to 1.2.307 and then 1.2.311.
For example, Current Version is 1.2.306 upgrade to 1.2.312:
1.2.307 -> 1.2.311 -> 1.2.312
Compatibility between databend-meta
Meta version | Backward compatible with |
---|---|
[0.9.41, 1.2.212) | [0.9.41, 1.2.212) |
[1.2.212, 1.2.479) | [0.9.41, 1.2.479) |
[1.2.479, +∞) | [1.2.288, +∞) |
-
1.2.53
Incompatible, rolling upgrade is allowed without snapshot transmitting. Snapshot format changed thus during rolling upgrading, it requires all node data to be up-to-date, ensure there is no need to replicate with snapshot. -
1.2.163
Feature: gRPC API:kv_read_v1()
is added. For stream reading. -
1.2.212
2023-11-16 Feature: raft API:install_snapshot_v1()
. Compatible with old versions. Rolling upgrade is supported. In this version, databend-meta raft-server introduced a new APIinstall_snapshot_v1()
. The raft-client will try to use either this new API or the originalinstall_snapshot()
. -
1.2.479
2024-05-21 Remove:install_snapshot()
(v0) from client and server. Theinstall_snapshot_v1()
is the only API to install snapshot, and becomes REQUIRED for the client. -
1.2.528
2024-06-13 Remove on-disk data versionV001
. The first version usingV002
is1.2.53
, 2023-08-08. Therefore, since1.2.528
, the oldest compatible version is1.2.53
. Consequently, compatibility remains unchanged from this version onward. -
1.2.552
2024-07-02 Introduce on-diskV003
, usingrotbl
format snapshot, which is compatible withV002
. The oldest compatible version is1.2.288
(1.2.212~1.2.287
are removed).
Compatibility of databend-meta on-disk data
The on-disk data of Databend-meta evolves over time while maintaining backward compatibility.
Identifying the versions
Upon startup, Databend-meta will display the on-disk data version:
For example, running databend-meta --single
produces:
Databend Metasrv
Version: v1.1.33-nightly-...
Working DataVersion: V0
On Disk Data:
Dir: ./.databend/meta
Version: version=V0, upgrading=None
Working DataVersion
denotes the version Databend-meta operates on.On Disk Data -- DataVersion
denotes the version of the on-disk data.
The Working DataVersion must be greater than or equal to the on-disk DataVersion; otherwise, it will panic.
The on-disk DataVersion must be compatible with the current Databend-meta version. If not, the system will prompt the user to downgrade Databend-meta and quit with a panic.
Automatic upgrade
When databend-meta
starting up, the on-disk is upgraded if it is compatible with the working DataVersion.
The upgrade progress will be printed to stderr
and to log file at INFO level, e.g.:
Upgrade on-disk data
From: V0(2023-04-21: compatible with openraft v07 and v08, using openraft::compat)
To: V001(2023-05-15: Get rid of compat, use only openraft v08 data types)
Begin upgrading: version: V0, upgrading: V001
Write header: version: V0, upgrading: V001
Upgraded 167 records
Finished upgrading: version: V001, upgrading: None
Write header: version: V001, upgrading: None
If databend-meta
crashes before upgrading finishes,
it will clear partially upgraded data and resume the upgrade when it starts up again.
Backup data compatibility
-
The exported backup data can only be imported with the same version of
databend-metactl
. -
The first line of the backup is the version, e.g.:
["header",{"DataHeader":{"key":"header","value":{"version":"V100","upgrading":null}}}]
-
NO automatic upgrade will be done when importing. Automatic upgrade will only be done when
databend-meta
is brought up.