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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.