Elasticsearch presents challenges with schema changes that typically necessitate reindexing, a process that can lead to significant downtime. To mitigate this, strategies like using aliases enable reindexing with zero downtime, ensuring that applications remain unaffected during the transition. This involves creating a new index with updated mappings, reindexing data from the old index, and then updating the alias to point to the new index atomically. Additional techniques include adding new fields without reindexing, using multi-fields to accommodate different data types, and employing aliases to manage different document types across multiple indices, allowing for flexible and efficient data management. The text also highlights recent updates and changes in Elasticsearch, advising readers to adopt modern practices such as setting valid content type headers in curl commands for compatibility with future versions.