Method RenameIndex

backend/store/model/database.go:1249–1277

RenameIndex renames an index in the table. Returns an error if the old index doesn't exist or new index already exists.

(oldName string, newName string)

// RenameIndex renames an index in the table.
// Returns an error if the old index doesn't exist or new index already exists.
func (t *TableMetadata) RenameIndex(oldName string, newName string) error {
	if oldName == newName {
		return nil
	}

	// Check if old index exists
	oldIndex := t.GetIndex(oldName)
	if oldIndex == nil {
		return errors.Errorf("index %q does not exist in table %q", oldName, t.proto.Name)
	}

	// Check if new index already exists
	if t.GetIndex(newName) != nil {
		return errors.Errorf("index %q already exists in table %q", newName, t.proto.Name)
	}

	// Remove from internal map using old name
	oldIndexID := normalizeNameByCaseSensitivity(oldName, t.isDetailCaseSensitive)
	delete(t.internalIndexes, oldIndexID)

	// Update the index name in the proto
	oldIndex.proto.Name = newName

	// Add back to internal map using new name
	newIndexID := normalizeNameByCaseSensitivity(newName, t.isDetailCaseSensitive)
	t.internalIndexes[newIndexID] = oldIndex

	return nil
}

// getIsDetailCaseSensitive is a special case for MySQL, MariaDB, and TiDB.
// From MySQL documentation: