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Databend Meta CLI

The binary databend-meta provides several handy commands to access the KVApi of databend meta service. databend-meta --help also includes a simple guide on using these CLI commands.

caution

These are low level API and should be avoided using if possible:

  • Some data stored in databend-meta are correlated, adding or deleting may break these internal consistency. E.g., deleting a database when there are still tables belonging to it.

  • Most data in databend-mata are raw bytes. Data interpreting is done on the client side, i.e., by databend-query. Modifying data may lead to compatibility issues.

note

The command line API is limited that:

  • only string key and string value are supported.
  • seq is not supported.

Set foo=bar:​

databend-meta --grpc-api-address 1.2.3.4:5678 --cmd kvapi::upsert --key foo --value bar

Output is the state before and after applying this command:

{
  "ident": null,
  "prev": {
    "seq": 18,
    "meta": null,
    "data": [ 98, 97, 114 ]
  },
  "result": {
    "seq": 20,
    "meta": null,
    "data": [ 98, 97, 114 ]
  }
}

Set foo=bar and inform databend-meta to delete it after 5 seconds:​

databend-meta --grpc-api-address 1.2.3.4:5678 --cmd kvapi::upsert --key foo --value bar --expire-after 5

Output is the state before and after applying this command and expire_at is set.

{
  "ident": null,
  "prev": {
    "seq": 20,
    "meta": null,
    "data": [ 98, 97, 114 ]
  },
  "result": {
    "seq": 21,
    "meta": {
      "expire_at": 1668996718
    },
    "data": [ 98, 97, 114 ]
  }
}

Delete foo:​

databend-meta --grpc-api-address 1.2.3.4:5678 --cmd kvapi::delete --key foo

Output is the state before and after applying this command and result is always null.

{
  "ident": null,
  "prev": {
    "seq": 22,
    "meta": null,
    "data": [ 98, 97, 114 ]
  },
  "result": null
}

Get foo:​

databend-meta --grpc-api-address 1.2.3.4:5678 --cmd kvapi::get --key foo

Output is the state of key foo.

{
  "seq": 23,
  "meta": null,
  "data": [ 98, 97, 114 ]
}

Get multiple keys with mget: foo,bar,wow:​

databend-meta --grpc-api-address 1.2.3.4:5678 --cmd kvapi::mget --key foo bar wow

Output is the states of every specified key.

[
  {
    "seq": 23,
    "meta": null,
    "data": [ 98, 97, 114 ]
  },
  null,
  null
]

List keys starting with foo/:​

databend-meta --grpc-api-address 1.2.3.4:5678 --cmd kvapi::list --prefix foo/

Output is the key values of every key starting with prefix.

[
  [
    "foo/a",
    {
      "seq": 24,
      "meta": null,
      "data": [ 98, 97, 114 ]
    }
  ],
  [
    "foo/b",
    {
      "seq": 25,
      "meta": null,
      "data": [ 119, 111, 119 ]
    }
  ]
]