Elasticsearch introduced a new mapping type called "alias" that enables users to define alternative names for fields within an index, enhancing search capabilities without requiring reindexing. This feature is particularly beneficial for renaming fields in time-based indices, as it allows users to implement new field names while maintaining access to older data. Field aliases also facilitate migrating indices to a common schema, such as ECS, by allowing searches across indices with different field names. In practical applications, such as monitoring telemetry data from the International Space Station, field aliases help standardize unit specifications in field names without disrupting historical data analysis. While aliases can be employed in search requests, queries, aggregations, and other search functionalities, they cannot be used when indexing documents, as they only apply to the search layer rather than the document source. This makes field aliases a lightweight alternative to data re-writing when the primary need is for search functionality rather than indexing.