...

• Proto changed for Query

// internal/proto/milvus.proto
message QueryResults {
  ...
- repeated schema.FieldData fields_data = 2;
+ bytes batch_record = 2;
}

Design Details(required)

Describe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.

## Compatibility, Deprecation, and Migration Plan(optional)
- What impact (if any) will there be on existing users?
- If we are changing behavior how will we phase out the older behavior?
- If we need special migration tools, describe them here.
- When will we remove the existing behavior?

After this MEP, Milvus will not be compatible with previous Milvus 2.0.0-rcX, because:

• the proto format between SDK and proxy changed
• binlog file format changed

We divide this MEP into 2 stages, all compatibility changes will be achieved in Stage 1 before Milvus 2.0.0, other internal changes can be left later.

Stage 1

1. Update InsertRequest in milvus.proto, change Insert to use Arrow format
2. Update SearchRequest/Hits in milvus.proto, and SearchResultData in schema.proto, change Search to use Arrow format
3. Update QueryResults in milvus.proto, change Query to use Arrow format
4. upgrade to Arrow-5.0.0
5. Change FillTargetEntry to column-based
6. Update Storage module to write Parquet from arrow directlyArrow, or read Arrow from Parquet directly. Write one Segment into one Parquet file.

Stage 2

1. Upgrade C++ Arrow module used in Storage from version 2.0.0 to 5.0.0
2. Remove all internal row-based data structure, including "RowData" in internalpb.InsertRequest, "row_data" in milvuspb.Hits, "row_data_" in C++ SearchResult.
3. Optimize search result flow

Test Plan(required)

Pass all CI flows

...