diff --git a/docs/design_docs/milvus_drop_collection_en.md b/docs/design_docs/milvus_drop_collection_en.md index a2215e5dd9..bdc46c5f46 100644 --- a/docs/design_docs/milvus_drop_collection_en.md +++ b/docs/design_docs/milvus_drop_collection_en.md @@ -1,5 +1,5 @@ # Drop Collection -`Milvus 2.0` use `Collection` to represent a set of data, like `Table` in traditional database. Users can create or drop `Collection`. Altering the `Schema` of `Collection` is not supported yet. This article introduces the execution path of `Drop Collection`, at the end of this article, you should know which components are involved in `Drop Collection`. +`Milvus 2.0` uses `Collection` to represent a set of data, like `Table` in traditional database. Users can create or drop `Collection`. Altering the `Schema` of `Collection` is not supported yet. This article introduces the execution path of `Drop Collection`. At the end of this article, you should know which components are involved in `Drop Collection`. The execution flow of `Drop Collection` is shown in the following figure: @@ -22,7 +22,7 @@ message DropCollectionRequest { } ``` -2. When received the `DropCollection` request, the `Proxy` would wraps this request into `DropCollectionTask`, and pushs this task into `DdTaskQueue` queue. After that, `Proxy` would call method of `WatiToFinish` to wait until the task finished. +2. Once the `DropCollection` request is received, the `Proxy` would wrap this request into `DropCollectionTask`, and push this task into `DdTaskQueue` queue. After that, `Proxy` would call method of `WatiToFinish` to wait until the task is finished. ```go type task interface { TraceCtx() context.Context @@ -52,9 +52,9 @@ type DropCollectionTask struct { } ``` -3. There is a backgroud service in `Proxy`, this service would get the `DropCollectionTask` from `DdTaskQueue`, and executes it in three phases. +3. There is a background service in `Proxy`, this service would get the `DropCollectionTask` from `DdTaskQueue`, and execute it in three phases: - `PreExecute`, do some static checking at this phase, such as check if `Collection Name` is legal etc. - - `Execute`, at thie phase, `Proxy` would send `DropCollection` request to `RootCoord` via `Grpc`,and wait the reponse, the `proto` is defined as follow: + - `Execute`, at this phase, `Proxy` would send `DropCollection` request to `RootCoord` via `Grpc`, and wait the response, the `proto` is defined as below: ```proto service RootCoord { ... @@ -64,9 +64,9 @@ type DropCollectionTask struct { ... } ``` - - `PostExecute`, `Proxy` would delete the `Collection`'s meta from global meta table at this phase. + - `PostExecute`, `Proxy` would delete `Collection`'s meta from global meta table at this phase. -4. `RootCoord` would wraps the `DropCollection` request into `DropCollectionReqTask`, and then call function `executeTask`. `executeTask` would return until the `context` is done or `DropCollectionReqTask.Execute` returned. +4. `RootCoord` would wrap the `DropCollection` request into `DropCollectionReqTask`, and then call function `executeTask`. `executeTask` would return until the `context` is done or `DropCollectionReqTask.Execute` is returned. ```go type reqTask interface { Ctx() context.Context @@ -81,13 +81,13 @@ type DropCollectionReqTask struct { } ``` -5. Firstly, `RootCoord` would delete `Collection`'s meta from `metaTable`, including `schema`,`partition`, `segment`,`index`, all of these delete operations are committed in one transaction. +5. Firstly, `RootCoord` would delete `Collection`'s meta from `metaTable`, including `schema`,`partition`, `segment`,`index`. All of these delete operations are committed in one transaction. 6. After `Collection`'s meta has been deleted from `metaTable`, `Milvus` would consider this collection has been deleted successfully. -7. `RootCoord` would alloc a timestamp from `TSO` before deleting `Collection`'s meta from `metaTable`, and this timestamp is considered as the point when the collection was deleted. +7. `RootCoord` would alloc a timestamp from `TSO` before deleting `Collection`'s meta from `metaTable`. This timestamp is considered as the point when the collection was deleted. -8. `RoooCoord` would send a message of `DropCollectionRequest` into `MsgStream`, and other components, who has subscribe to the `MsgStream`, would be notified. The `Proto` of `DropCollectionRequest` is defined as follow: +8. `RootCoord` would send a message of `DropCollectionRequest` into `MsgStream`. Thus other components, who have subscribed to the `MsgStream`, would be notified. The `Proto` of `DropCollectionRequest` is defined as below: ```proto message DropCollectionRequest { common.MsgBase base = 1; @@ -101,7 +101,7 @@ message DropCollectionRequest { 9. After these operations, `RootCoord` would update internal timestamp. -10. Then `RootCoord` would start a `ReleaseCollection` request to `QueryCoord` via `Grpc` , notify `QueryCoord` to release all the resouces that related to this `Collection`. This `Grpc` request is done in another `goroutine`, so it would not block the main thread. The `proto` is defined as follow: +10. Then `RootCoord` would start a `ReleaseCollection` request to `QueryCoord` via `Grpc` , notify `QueryCoord` to release all resources that related to this `Collection`. This `Grpc` request is done in another `goroutine`, so it would not block the main thread. The `proto` is defined as follows: ```proto service QueryCoord { ... @@ -119,7 +119,7 @@ message ReleaseCollectionRequest { } ``` -11. At last, `RootCoord` would send `InvalidateCollectionMetaCache` request to each `Proxy`, notify `Proxy` to remove `Collection`'s meta, the `proto` is defined as follow: +11. At last, `RootCoord` would send `InvalidateCollectionMetaCache` request to each `Proxy`, notify `Proxy` to remove `Collection`'s meta. The `proto` is defined as follows: ```proto service Proxy { ... @@ -135,17 +135,17 @@ message InvalidateCollMetaCacheRequest { string collection_name = 3; } ``` - -12. The execution flow of `QueryCoord.ReleaseCollection` is shown in the follwing figure. -![releae_collection](./graphs/dml_release_collection.png) +12. The execution flow of `QueryCoord.ReleaseCollection` is shown in the following figure: -13. `QueryCoord` would wraps `ReleaseCollection` into `ReleaseCollectionTask`, and push the task into `TaskScheduler` +![release_collection](./graphs/dml_release_collection.png) -14. There is a backgroud service in `QueryCoord`, this service would get the `ReleaseCollectionTask` from `TaskScheduler`, and executes it in three phases. +13. `QueryCoord` would wrap `ReleaseCollection` into `ReleaseCollectionTask`, and push the task into `TaskScheduler` + +14. There is a background service in `QueryCoord`. This service would get the `ReleaseCollectionTask` from `TaskScheduler`, and execute it in three phases: - `PreExecute`, `ReleaseCollectionTask` would only print debug log at this phase. - `Execute`, there are two jobs at this phase: - - send a `ReleaseDQLMessageStream` request to `RootCoord` via `Grpc`, `RootCoord` would redirect the `ReleaseDQLMessageStream` request to each `Proxy`, notify the `Proxy` that not processing any message of this `Collection` anymore. The `proto` is defined as follow: + - send a `ReleaseDQLMessageStream` request to `RootCoord` via `Grpc`, `RootCoord` would redirect the `ReleaseDQLMessageStream` request to each `Proxy`, and notify the `Proxy` that stop processing any message of this `Collection` anymore. The `proto` is defined as follows: ```proto message ReleaseDQLMessageStreamRequest { common.MsgBase base = 1; @@ -153,7 +153,7 @@ message InvalidateCollMetaCacheRequest { int64 collectionID = 3; } ``` - - send a `ReleaseCollection` request to each `QueryNode` via `Grpc`, notify the `QueryNode` to release all the resources related to this `Collection`, including `Index`, `Segment`, `FlowGraph`, etc. `QueryNode` would no longer read any message from this `Collection`'s `MsgStream` anymore + - send a `ReleaseCollection` request to each `QueryNode` via `Grpc`, and notify the `QueryNode` to release all the resources related to this `Collection`, including `Index`, `Segment`, `FlowGraph`, etc. `QueryNode` would no longer read any message from this `Collection`'s `MsgStream` anymore ```proto service QueryNode { ... @@ -172,18 +172,14 @@ message InvalidateCollMetaCacheRequest { ``` - `PostExecute`, `ReleaseCollectionTask` would only print debug log at this phase. -15. After these operations, `QueryCoord` would send `ReleaseCollection`'s reponse to `RootCoord +15. After these operations, `QueryCoord` would send `ReleaseCollection`'s response to `RootCoord`. -16. At `Step 8`, `RoooCoord` has sent a message of `DropCollectionRequest` into `MsgStream`, `DataNode` would subscribe this `MsgStream`, so `DataNode` would be notified to released the resources. The execution flow is shown in the following figure. +16. At `Step 8`, `RootCoord` has sent a message of `DropCollectionRequest` into `MsgStream`. `DataNode` would subscribe this `MsgStream`, so that it would be notified to release related resources. The execution flow is shown in the following figure. -![releae_collection](./graphs/dml_release_flow_graph_on_data_node.png) +![release_collection](./graphs/dml_release_flow_graph_on_data_node.png) -17. In `DataNode`, each `MsgStream` will have a `FlowGraph`, all the messages are processed by that `FlowGraph`. When the `DataNode` receives the message of `DropCollectionRequest`, `DataNode` would notify `BackouGroundGC`, which is a background service on `DataNode`, to release the resouces. +17. In `DataNode`, each `MsgStream` will have a `FlowGraph`, which processes all messages. When the `DataNode` receives the message of `DropCollectionRequest`, `DataNode` would notify `BackGroundGC`, which is a background service on `DataNode`, to release resources. *Notes*: -1. Currently, the `DataCoord` has not response to the `DropCollection`, so the `Collection`'s `segment meta` are still exist in the `DataCoord`'s `metaTable`, and the `Binlog` files belongs to this `Collection` are still exist on the persistent storage. -2. Currently, the `IndexCoord` has not response to the `DropCollection`, so the `Collection`'s `index file` are still exist on the persistent storage. - - - - +1. Currently, the `DataCoord` doesn't have response to the `DropCollection`. So the `Collection`'s `segment meta` still exists in the `DataCoord`'s `metaTable`, and the `Binlog` files belonging to this `Collection` still exist in the persistent storage. +2. Currently, the `IndexCoord` doesn't have response to the `DropCollection`. So the `Collection`'s `index file` still exists in the persistent storage.