- Elasticsearch Guide: other versions:
- Getting Started
- Setup
- Breaking changes
- API Conventions
- Document APIs
- Search APIs
- Search
- URI Search
- Request Body Search
- Search Template
- Search Shards API
- Aggregations
- Min Aggregation
- Max Aggregation
- Sum Aggregation
- Avg Aggregation
- Stats Aggregation
- Extended Stats Aggregation
- Value Count Aggregation
- Percentiles Aggregation
- Percentile Ranks Aggregation
- Cardinality Aggregation
- Geo Bounds Aggregation
- Top hits Aggregation
- Scripted Metric Aggregation
- Global Aggregation
- Filter Aggregation
- Filters Aggregation
- Missing Aggregation
- Nested Aggregation
- Reverse nested Aggregation
- Children Aggregation
- Terms Aggregation
- Significant Terms Aggregation
- Range Aggregation
- Date Range Aggregation
- IPv4 Range Aggregation
- Histogram Aggregation
- Date Histogram Aggregation
- Geo Distance Aggregation
- GeoHash grid Aggregation
- Facets
- Suggesters
- Multi Search API
- Count API
- Search Exists API
- Validate API
- Explain API
- Percolator
- More Like This API
- Field stats API
- Indices APIs
- Create Index
- Delete Index
- Get Index
- Indices Exists
- Open / Close Index API
- Put Mapping
- Get Mapping
- Get Field Mapping
- Types Exists
- Delete Mapping
- Index Aliases
- Update Indices Settings
- Get Settings
- Analyze
- Index Templates
- Warmers
- Status
- Indices Stats
- Indices Segments
- Indices Recovery
- Clear Cache
- Flush
- Refresh
- Optimize
- Shadow replica indices
- Upgrade
- cat APIs
- Cluster APIs
- Query DSL
- Queries
- Match Query
- Multi Match Query
- Bool Query
- Boosting Query
- Common Terms Query
- Constant Score Query
- Dis Max Query
- Filtered Query
- Fuzzy Like This Query
- Fuzzy Like This Field Query
- Function Score Query
- Fuzzy Query
- GeoShape Query
- Has Child Query
- Has Parent Query
- Ids Query
- Indices Query
- Match All Query
- More Like This Query
- Nested Query
- Prefix Query
- Query String Query
- Simple Query String Query
- Range Query
- Regexp Query
- Span First Query
- Span Multi Term Query
- Span Near Query
- Span Not Query
- Span Or Query
- Span Term Query
- Term Query
- Terms Query
- Top Children Query
- Wildcard Query
- Minimum Should Match
- Multi Term Query Rewrite
- Template Query
- Filters
- And Filter
- Bool Filter
- Exists Filter
- Geo Bounding Box Filter
- Geo Distance Filter
- Geo Distance Range Filter
- Geo Polygon Filter
- GeoShape Filter
- Geohash Cell Filter
- Has Child Filter
- Has Parent Filter
- Ids Filter
- Indices Filter
- Limit Filter
- Match All Filter
- Missing Filter
- Nested Filter
- Not Filter
- Or Filter
- Prefix Filter
- Query Filter
- Range Filter
- Regexp Filter
- Script Filter
- Term Filter
- Terms Filter
- Type Filter
- Queries
- Mapping
- 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
WARNING: Version 1.7 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.
Has Child Filter
editHas Child Filter
editThe has_child
filter accepts a query and the child type to run
against, and results in parent documents that have child docs matching
the query. Here is an example:
{ "has_child" : { "type" : "blog_tag", "query" : { "term" : { "tag" : "something" } } } }
The type
is the child type to query against. The parent type to return
is automatically detected based on the mappings.
The way that the filter is implemented is by first running the child query, doing the matching up to the parent doc for each document matched.
The has_child
filter also accepts a filter instead of a query:
{ "has_child" : { "type" : "comment", "filter" : { "term" : { "user" : "john" } } } }
Min/Max Children
editThe has_child
filter allows you to specify that a minimum and/or maximum
number of children are required to match for the parent doc to be considered
a match:
{ "has_child" : { "type" : "comment", "min_children": 2, "max_children": 10, "filter" : { "term" : { "user" : "john" } } } }
The execution speed of the has_child
filter is equivalent
to that of the has_child
query when min_children
or max_children
is specified.
Memory Considerations
editIn order to support parent-child joins, all of the (string) parent IDs must be resident in memory (in the field data cache. Additionally, every child document is mapped to its parent using a long value (approximately). It is advisable to keep the string parent ID short in order to reduce memory usage.
You can check how much memory is being used by the ID cache using the indices stats or nodes stats APIS, eg:
curl -XGET "http://localhost:9200/_stats/id_cache?pretty&human"
Caching
editThe has_child
filter cannot be cached in the filter cache. The _cache
and _cache_key
options are a no-op in this filter. Also any filter that
wraps the has_child
filter either directly or indirectly will not be cached.
On this page