refactor: add selection to bulk (#232)

* feat: add selection field to BulkInsertRequest

* add schema section

* change bulk request

* replace vec<u8> with bytes

* wip

* wip

* chore: rebase main

* fix: clippy

* refactor arrow ipc writes

proto/greptime/v1/region/server.proto

@@ -53,7 +53,7 @@ message RegionRequest {
     CreateRequests creates = 13;
     DropRequests drops = 14;
     AlterRequests alters = 15;
-    BulkInsertRequests bulk_inserts = 16;
+    BulkInsertRequest bulk_insert = 16;
     SyncRequest sync = 17;
   }
 }
@@ -108,7 +108,7 @@ message CreateRequest {
 // Same as CreateRequests, but for dropping regions.
 message DropRequests { repeated DropRequest requests = 1; }
 
-message DropRequest { 
+message DropRequest {
   uint64 region_id = 1;
   // Only used by Metric Engine, for fast path drop.
   // It only works for Metric Engine, and will be ignored by other engines.
@@ -186,15 +186,15 @@ message RegionColumnDef {
 }
 
 // Request of bulk ingestion API.
-message BulkInsertRequests { repeated BulkInsertRequest requests = 1; }
-
-enum BulkInsertType {
-  ARROW_IPC = 0;
+message BulkInsertRequest {
+  oneof body {
+    ArrowIpc arrow_ipc = 1;
+  }
 }
 
-message BulkInsertRequest {
+message ArrowIpc {
   uint64 region_id = 1;
-  BulkInsertType payload_type = 2;
+  bytes schema = 2;
   bytes payload = 3;
 }