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Merge pull request #5082 from xiang90/kv_d

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doc: add doc for kv message
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Xiang Li 2016-04-14 15:17:04 -07:00
commit 74153ffa45
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Documentation/api_v3.md
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@ -1,6 +1,33 @@
# etcd3 API
TODO: API doc
TODO: finish API doc
## Key-Value API
Key-Value API is used to manipulate key-value pairs stored inside etcd. The key-value API is defined as a [gRPC service][kv-service]. The Key-Value pair is defined as structured data in [protobuf format][kv-proto].
### Key-Value Pair
A key-value pair is the smallest unit that the key-value API can manipulate. Each key-value pair has a number of fields:
```protobuf
message KeyValue {
bytes key = 1;
int64 create_revision = 2;
int64 mod_revision = 3;
int64 version = 4;
bytes value = 5;
int64 lease = 6;
}
```
* Key - key in bytes. An empty key is not allowed.
* Value - value in bytes.
* Version - version is the version of the key. A deletion resets the version to zero and any modification of the key increases its version.
* Create_Revision - revision of the last creation on the key.
* Mod_Revision - revision of the last modification on the key.
* Lease - the ID of the lease attached to the key. If lease is 0, then no lease is attached to the key.
## Data Model
@ -83,10 +110,12 @@ etcd does not ensure linearizability for watch operations. Users are expected to
etcd ensures linearizability for all other operations by default. Linearizability comes with a cost, however, because linearized requests must go through the Raft consensus process. To obtain lower latencies and higher throughput for read requests, clients can configure a request’s consistency mode to `serializable`, which may access stale data with respect to quorum, but removes the performance penalty of linearized accesses' reliance on live consensus.
[persistent-ds]: [https://en.wikipedia.org/wiki/Persistent_data_structure]
[btree]: [https://en.wikipedia.org/wiki/B-tree]
[b+tree]: [https://en.wikipedia.org/wiki/B%2B_tree]
[seq_consistency]: [https://en.wikipedia.org/wiki/Consistency_model#Sequential_consistency]
[strict_consistency]: [https://en.wikipedia.org/wiki/Consistency_model#Strict_consistency]
[serializable_isolation]: [https://en.wikipedia.org/wiki/Isolation_(database_systems)#Serializable]
[Linearizability]: [#Linearizability]
[persistent-ds]: https://en.wikipedia.org/wiki/Persistent_data_structure
[btree]: https://en.wikipedia.org/wiki/B-tree
[b+tree]: https://en.wikipedia.org/wiki/B%2B_tree
[seq_consistency]: https://en.wikipedia.org/wiki/Consistency_model#Sequential_consistency
[strict_consistency]: https://en.wikipedia.org/wiki/Consistency_model#Strict_consistency
[serializable_isolation]: https://en.wikipedia.org/wiki/Isolation_(database_systems)#Serializable
[Linearizability]: #Linearizability
[kv-proto]: https://github.com/coreos/etcd/blob/master/storage/storagepb/kv.proto
[kv-service]: https://github.com/coreos/etcd/blob/master/etcdserver/etcdserverpb/rpc.proto