feat: truncate table (#70)

Author: DevilExileSu

c++/greptime/v1/ddl.pb.cc

@@ -34,6 +34,7 @@ message DdlRequest {
     DropTableExpr drop_table = 4;
     FlushTableExpr flush_table = 5;
     CompactTableExpr compact_table = 6;
+    TruncateTableExpr truncate_table = 7;
   }
 }
 
@@ -93,6 +94,13 @@ message CreateDatabaseExpr {
   bool create_if_not_exists = 2;
 }
 
+message TruncateTableExpr {
+  string catalog_name = 1;
+  string schema_name = 2;
+  string table_name = 3;
+  TableId table_id = 4;
+}
+
 message AddColumns { repeated AddColumn add_columns = 1; }
 
 message DropColumns { repeated DropColumn drop_columns = 1; }

c++/greptime/v1/ddl.pb.h

@@ -47,13 +47,18 @@ message AlterTableTask{
     AlterExpr alter_table = 1;
 }
 
+message TruncateTableTask {
+    TruncateTableExpr truncate_table = 1;
+}
+
 message SubmitDdlTaskRequest {
     RequestHeader header = 1;
 
     oneof task {
         CreateTableTask create_table_task = 2;
         DropTableTask drop_table_task = 3;
         AlterTableTask alter_table_task = 4;
+        TruncateTableTask truncate_table_task = 5;
      }
 }