server_action_rename_column.qmd

---
title: "`rename_column` Action"
description: "Implement the rename_column DoAction to support ALTER TABLE RENAME COLUMN statements for renaming table columns."
---

The `rename_column` action renames an existing column in a table. This action is invoked when executing an `ALTER TABLE ... RENAME COLUMN` SQL statement.

## SQL Example

```sql
ALTER TABLE example.main.employees RENAME COLUMN emp_id TO employee_id;
ALTER TABLE example.main.employees RENAME COLUMN dept TO department;
```

## Input Parameters

The action receives a single `msgpack`-serialized parameter:

```c++
// The base class for all alter parameters.
struct AirportAlterBase
{
  //! Catalog name to alter
  std::string catalog;
  //! Schema name to alter
  std::string schema;
  //! Entry name to alter
  std::string name;
  bool ignore_not_found;
};

struct AirportAlterTableRenameColumnParameters : AirportAlterBase
{
  std::string old_name;
  std::string new_name;

  MSGPACK_DEFINE_MAP(catalog, schema, name, ignore_not_found, new_name, old_name);
};
```

## Return Value

The action must return a single [`FlightInfo`](https://github.com/apache/arrow/blob/ac1f05f28e18e85ee55cf7aaf3c8ae1ffe0e92d7/format/Flight.proto#L275) structure representing the modified table with the column renamed. The `app_metadata` field must be populated appropriately to identify the flight as a table.