Format

The format mapping parameter specifies the built-in date formats that a date field can accept during indexing. By defining the expected date formats, you ensure that date values are correctly parsed and stored, facilitating accurate search and aggregation operations.

Example: Defining a custom date format

Create an events index with the event_date field configured to a custom yyyy-MM-dd HH:mm:ss date format:

PUT events { "mappings": { "properties": { "event_date": { "type": "date", "format": "yyyy-MM-dd HH:mm:ss" } } } } 

Index a document using the specified format for the event_date field:

PUT events/_doc/1 { "event_name": "Conference", "event_date": "2025-03-26 15:30:00" } 

Example: Using multiple date formats

Create an index containing a log_timestamp field, which accepts both the custom yyyy-MM-dd HH:mm:ss date format and the epoch_millis format:

PUT logs { "mappings": { "properties": { "log_timestamp": { "type": "date", "format": "yyyy-MM-dd HH:mm:ss||epoch_millis" } } } } 

Index the first document using the custom format:

PUT logs/_doc/1 { "message": "System rebooted", "log_timestamp": "2025-03-26 08:45:00" } 

Index the second document using the millisecond format:

PUT logs/_doc/2 { "message": "System updated", "log_timestamp": 1711442700000 } 

Built-in date formats

For a comprehensive list of built-in date formats, see Built-in formats.