milvus/docs/developer_guides/chap09_data_service.md

## 8. Data Service



#### 8.1 Overview

<img src="./figs/data_service.png" width=700>

#### 8.2 Data Service Interface

```go
type DataService interface {
  Service
  
  RegisterNode(req RegisterNodeRequest) (RegisterNodeResponse, error)
  Flush(req FlushRequest) error
  
  AssignSegmentID(req AssignSegIDRequest) (AssignSegIDResponse, error)
  ShowSegments(req ShowSegmentRequest) (ShowSegmentResponse, error)
  GetSegmentStates(req SegmentStatesRequest) (SegmentStatesResponse, error)
  GetSegmentInfo(req SegmentInfoRequest) (SegmentInfoResponse, error)

  GetInsertBinlogPaths(req InsertBinlogPathRequest) (InsertBinlogPathsResponse, error)

  GetSegmentInfoChannel(req InsertChannelRequest) (StringResponse, error)
  GetInsertChannels(req InsertChannelRequest) (StringList, error)

  GetCollectionStatistics(req CollectionStatsRequest) (CollectionStatsResponse, error)
  GetPartitionStatistics(req PartitionStatsRequest) (PartitionStatsResponse, error)
  
}
```



* *MsgBase*

```go
type MsgBase struct {
  MsgType MsgType
  MsgID	UniqueID
  Timestamp Timestamp
  SourceID UniqueID
}
```

* *RegisterNode*

```go
type RegisterNodeRequest struct {
  MsgBase
  Address string
  Port int64
}

type RegisterNodeResponse struct {
  //InitParams
}
```

* *AssignSegmentID*

```go
type SegIDRequest struct {
  Count uint32
  ChannelName string
	CollectionID UniqueID
  PartitionID UniqueID
}

type AssignSegIDRequest struct {
  MsgBase
  PerChannelRequest []SegIDRequest
}

type SegIDAssignment struct {
  SegmentID UniqueID
  ChannelName string
  Count uint32
	CollectionID UniqueID
  PartitionID UniqueID
  ExpireTime Timestamp
}

type AssignSegIDResponse struct {
  PerChannelResponse []SegIDAssignment
}
```



* *Flush*

```go
type FlushRequest struct {
  MsgBase
  DbID UniqueID
  CollectionID UniqueID
}
```



* *ShowSegments*

```go
type ShowSegmentRequest struct {
  MsgBase
  CollectionID UniqueID
  PartitionID UniqueID
}

type ShowSegmentResponse struct {
  SegmentIDs []UniqueID
}
```



* *GetSegmentStates*

```go
enum SegmentState {
    NONE = 0;
    NOT_EXIST = 1;
    GROWING = 2;
    SEALED = 3;
}

type SegmentStatesRequest struct {
  MsgBase
  SegmentID UniqueID
}

type SegmentStatesResponse struct {
  State SegmentState
  OpenTime Timestamp
  SealedTime Timestamp
  MsgStartPositions []msgstream.MsgPosition
  MsgEndPositions []msgstream.MsgPosition
}
```

* *GetSegmentInfo*

```go
type SegmentInfoRequest  struct{
  MsgBase
  SegmentIDs [] UniqueID
}
```

```go
type SegmentInfo struct {
	SegmentID            UniqueID
	CollectionID         UniqueID
	PartitionID          UniqueID
	InsertChannel        string
	OpenTime             Timestamp
	SealedTime           Timestamp
	FlushedTime          Timestamp
	NumRows              int64
	MemSize              int64
	State                SegmentState
	StartPosition        []Msgstream.MsgPosition
	EndPosition          []Msgstream.MsgPosition
}
```

```go
type SegmentInfoResponse  struct{
  infos []SegmentInfo
}
```

* *GetInsertBinlogPaths*

```go
type InsertBinlogPathRequest struct {
  MsgBase
  SegmentID UniqueID
}

type InsertBinlogPathsResponse struct {
  FieldIDToPaths map[int64][]string
}
```



* *GetInsertChannels*

```go
type InsertChannelRequest struct {
  MsgBase
  DbID UniqueID
  CollectionID UniqueID
}
```


* *GetCollectionStatistics*

```go
type CollectionStatsRequest struct {
  MsgBase
  DbName string
  CollectionName string
}
type CollectionStatsResponse struct {
  Stats []KeyValuePair
}
```



* *GetPartitionStatistics*

```go
type PartitionStatsRequest struct {
  MsgBase
  DbName string
  CollectionName string
  PartitionName string
}
type PartitionStatsResponse struct {
  Stats []KeyValuePair
}
```


#### 8.2 Insert Channel

```go
type InsertRequest struct {
  MsgBase
  DbName string
  CollectionName string
  PartitionName string
  DbID UniqueID
  CollectionID UniqueID
  PartitionID UniqueID
  RowData []Blob
  HashKeys []uint32
}
```



#### 8.2 Data Node Interface

```go
type DataNode interface {
  Service

  GetComponentStates() (ComponentStates, error)
  GetTimeTickChannel() (StringResponse, error)
  GetStatisticsChannel() (StringResponse, error)
  
  WatchDmChannels(WatchDmChannelRequest) error
  FlushSegments(FlushSegRequest) (Status, error)
  //WatchDdChannel(channelName string) error
  //SetTimeTickChannel(channelName string) error
  //SetStatisticsChannel(channelName string) error
  
  SetMasterServiceInterface(MasterServiceInterface) error
  SetDataServiceInterface(DataServiceInterface) error
}
```

```go
type DataServiceInterface interface {
  GetComponentStates() (ComponentStates, error)
  RegisterNode(RegisterNodeRequest) (RegisterNodeResponse, error)
}
```
```go
type MasterServiceInterface interface {
  GetComponentStates() (ComponentStates, error)
  AllocID(IDRequest) (IDResponse, error)
  ShowCollections(ShowCollectionRequest) (ShowCollectionResponse, error)
  DescribeCollection(DescribeCollectionRequest) (DescribeCollectionResponse, error)
}

```


* *WatchDmChannels*

```go
type WatchDmChannelRequest struct {
  MsgBase
  InsertChannelNames []string
}
```

* *FlushSegments*

```go
type FlushSegRequest struct {
  MsgBase
  DbID UniqueID
  CollectionID UniqueID
  SegmentID []UniqueID
}
```

* *SegmentStatistics*

```go
type SegmentStatisticsUpdates struct {
    SegmentID UniqueID
    MemorySize int64
    NumRows int64
}

type SegmentStatistics struct{
    MsgBase
    SegStats []*SegmentStatisticsUpdates
}
```