- Elasticsearch Guide: other versions:
- Getting Started
- Setup
- Breaking changes
- Breaking changes in 2.0
- Removed features
- Network changes
- Multiple
path.data
striping - Mapping changes
- CRUD and routing changes
- Query DSL changes
- Search changes
- Aggregation changes
- Parent/Child changes
- Scripting changes
- Index API changes
- Snapshot and Restore changes
- Plugin and packaging changes
- Setting changes
- Stats, info, and
cat
changes - Java API changes
- Breaking changes in 2.0
- API Conventions
- Document APIs
- Search APIs
- Aggregations
- Metrics Aggregations
- Bucket Aggregations
- Children Aggregation
- Date Histogram Aggregation
- Date Range Aggregation
- Filter Aggregation
- Filters Aggregation
- Geo Distance Aggregation
- GeoHash grid Aggregation
- Global Aggregation
- Histogram Aggregation
- IPv4 Range Aggregation
- Missing Aggregation
- Nested Aggregation
- Range Aggregation
- Reverse nested Aggregation
- Sampler Aggregation
- Significant Terms Aggregation
- Terms Aggregation
- Pipeline Aggregations
- Caching heavy aggregations
- Returning only aggregation results
- Aggregation Metadata
- Indices APIs
- Create Index
- Delete Index
- Get Index
- Indices Exists
- Open / Close Index API
- Put Mapping
- Get Mapping
- Get Field Mapping
- Types Exists
- Index Aliases
- Update Indices Settings
- Get Settings
- Analyze
- Index Templates
- Warmers
- Shadow replica indices
- Indices Stats
- Indices Segments
- Indices Recovery
- Indices Shard Stores
- Clear Cache
- Flush
- Refresh
- Optimize
- Upgrade
- cat APIs
- Cluster APIs
- Query DSL
- Mapping
- Field datatypes
- Meta-Fields
- Mapping parameters
analyzer
boost
coerce
copy_to
doc_values
dynamic
enabled
fielddata
format
geohash
geohash_precision
geohash_prefix
ignore_above
ignore_malformed
include_in_all
index
index_options
lat_lon
fields
norms
null_value
position_increment_gap
precision_step
properties
search_analyzer
similarity
store
term_vector
- Dynamic Mapping
- Transform
- Analysis
- Analyzers
- Tokenizers
- Token Filters
- Standard Token Filter
- ASCII Folding Token Filter
- Length Token Filter
- Lowercase Token Filter
- Uppercase Token Filter
- NGram Token Filter
- Edge NGram Token Filter
- Porter Stem Token Filter
- Shingle Token Filter
- Stop Token Filter
- Word Delimiter Token Filter
- Stemmer Token Filter
- Stemmer Override Token Filter
- Keyword Marker Token Filter
- Keyword Repeat Token Filter
- KStem Token Filter
- Snowball Token Filter
- Phonetic Token Filter
- Synonym Token Filter
- Compound Word Token Filter
- Reverse Token Filter
- Elision Token Filter
- Truncate Token Filter
- Unique Token Filter
- Pattern Capture Token Filter
- Pattern Replace Token Filter
- Trim Token Filter
- Limit Token Count Token Filter
- Hunspell Token Filter
- Common Grams Token Filter
- Normalization Token Filter
- CJK Width Token Filter
- CJK Bigram Token Filter
- Delimited Payload Token Filter
- Keep Words Token Filter
- Keep Types Token Filter
- Classic Token Filter
- Apostrophe Token Filter
- Character Filters
- ICU Analysis Plugin
- Modules
- Index Modules
- Testing
- Glossary of terms
- Release Notes
WARNING: Version 2.0 of Elasticsearch has passed its EOL date.
This documentation is no longer being maintained and may be removed. If you are running this version, we strongly advise you to upgrade. For the latest information, see the current release documentation.
Nested datatype
editNested datatype
editThe nested
type is a specialised version of the object
datatype
that allows arrays of objects to be indexed and queried independently of each
other.
How arrays of objects are flattened
editArrays of inner object
fields do not work the way you may expect.
Lucene has no concept of inner objects, so Elasticsearch flattens object
hierarchies into a simple list of field names and values. For instance, the
following document:
PUT my_index/my_type/1 { "group" : "fans", "user" : [ { "first" : "John", "last" : "Smith" }, { "first" : "Alice", "last" : "White" } ] }
would be transformed internally into a document that looks more like this:
{ "group" : "fans", "user.first" : [ "alice", "john" ], "user.last" : [ "smith", "white" ] }
The user.first
and user.last
fields are flattened into multi-value fields,
and the association between alice
and white
is lost. This document would
incorrectly match a query for alice AND smith
:
GET my_index/_search { "query": { "bool": { "must": [ { "match": { "user.first": "Alice" }}, { "match": { "user.last": "Smith" }} ] } } }
Using nested
fields for arrays of objects
editIf you need to index arrays of objects and to maintain the independence of
each object in the array, you should use the nested
datatype instead of the
object
datatype. Internally, nested objects index each object in
the array as a separate hidden document, meaning that each nested object can be
queried independently of the others, with the nested
query:
PUT my_index { "mappings": { "my_type": { "properties": { "user": { "type": "nested" } } } } } PUT my_index/my_type/1 { "group" : "fans", "user" : [ { "first" : "John", "last" : "Smith" }, { "first" : "Alice", "last" : "White" } ] } GET my_index/_search { "query": { "nested": { "path": "user", "query": { "bool": { "must": [ { "match": { "user.first": "Alice" }}, { "match": { "user.last": "Smith" }} ] } } } } } GET my_index/_search { "query": { "nested": { "path": "user", "query": { "bool": { "must": [ { "match": { "user.first": "Alice" }}, { "match": { "user.last": "White" }} ] } }, "inner_hits": { "highlight": { "fields": { "user.first": {} } } } } }
The |
|
This query doesn’t match because |
|
This query matches because |
|
|
Nested documents can be:
-
queried with the
nested
query. -
analyzed with the
nested
andreverse_nested
aggregations. - sorted with nested sorting.
- retrieved and highlighted with nested inner hits.
Parameters for nested
fields
editThe following parameters are accepted by nested
fields:
Whether or not new |
|
Sets the default |
|
The fields within the nested object, which can be of any
datatype, including |
Because nested documents are indexed as separate documents, they can only be
accessed within the scope of the nested
query, the
nested
/reverse_nested
, or nested inner hits.
For instance, if a string field within a nested document has
index_options
set to offsets
to allow use of the postings
highlighter, these offsets will not be available during the main highlighting
phase. Instead, highlighting needs to be performed via
nested inner hits.
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