Elasticsearch will undergo significant changes with the release of JDK 23 due to the removal of the COMPAT locale database, leaving the CLDR database as the sole option for locale data. This shift impacts how Elasticsearch handles date formats, particularly those using textual and week-date fields, as the CLDR database introduces variations in string representations and week-date calculations. Elasticsearch versions 8.16.0 and above will ship with JDK 23, defaulting to the CLDR database, and the default locale for date fields will change to "en" to mitigate root locale changes. Users employing custom date formatters may need to adapt their data ingestion and processing strategies to accommodate these changes, and Elasticsearch will provide deprecation warnings for affected formats. Elasticsearch versions prior to 8.16.0 will continue using the COMPAT database on JDK 22, but versions 7.17.24 and 8.15.1 and earlier will lack locale data on JDK 23. Future Elasticsearch releases will standardize the use of the CLDR locale database, regardless of the JDK version.