Mapping Parameters

1. format

used to customize format for date fields

• using default format is recommended
• java's DateFormatter syntax : ex) "dd/MM/yyy"
• built-in formats : ex) "epoch_second"

2. properties

defines nested fields for object and nested fields

3. coerce

used to enable or disable coercion of values (enabled by default)

4. doc_values

• Doc values is data structure other than Inverted Indexes used in Elasticsearch

• Doc Values is optimized for a different data access pattern such as

  • sort results alphabetically
  • aggregate values

• essentially uninverted inverted index

• used for sorting, aggregations, and scripting

• set false to save disk space and indexing overhead

5. norms

• norms : storage of various normalization factors that are used to compute relevance scores
• norms can be disabled to save disk space
  • useful for fields that won't be used for relevance scoring

6. index

disables indexing for a field

• values are still stored within _source
• useful if won't be used for search queries
• save disk space
• often used for time series data

7. null_value

• NULL values cannot be indexed or searched
• use this parameter to replace NULL values with another value
• only works for explicit NULL values
• replacement value must be of the same data type as the field
• does not affect value stored within _source

8. copy_to

used to copy multiple field values into a group field

• values are copies instead of terms/tokens
  • analyzer of the target field is used for the values
• target field is not part of _source