- Elasticsearch Guide: other versions:
- Getting Started
- Set up Elasticsearch
- Installing Elasticsearch
- Configuring Elasticsearch
- Important Elasticsearch configuration
- Secure Settings
- Bootstrap Checks
- Heap size check
- File descriptor check
- Memory lock check
- Maximum number of threads check
- Max file size check
- Maximum size virtual memory check
- Maximum map count check
- Client JVM check
- Use serial collector check
- System call filter check
- OnError and OnOutOfMemoryError checks
- Early-access check
- G1GC check
- Important System Configuration
- Upgrading Elasticsearch
- Stopping Elasticsearch
- Set up X-Pack
- Breaking changes
- Breaking changes in 5.6
- Breaking changes in 5.5
- Breaking changes in 5.4
- Breaking changes in 5.3
- Breaking changes in 5.2
- Breaking changes in 5.1
- Breaking changes in 5.0
- Search and Query DSL changes
- Mapping changes
- Percolator changes
- Suggester changes
- Index APIs changes
- Document API changes
- Settings changes
- Allocation changes
- HTTP changes
- REST API changes
- CAT API changes
- Java API changes
- Packaging
- Plugin changes
- Filesystem related changes
- Path to data on disk
- Aggregation changes
- Script related changes
- API Conventions
- Document APIs
- Search APIs
- Aggregations
- Metrics Aggregations
- Avg Aggregation
- Cardinality Aggregation
- Extended Stats Aggregation
- Geo Bounds Aggregation
- Geo Centroid Aggregation
- Max Aggregation
- Min Aggregation
- Percentiles Aggregation
- Percentile Ranks Aggregation
- Scripted Metric Aggregation
- Stats Aggregation
- Sum Aggregation
- Top hits Aggregation
- Value Count Aggregation
- Bucket Aggregations
- Adjacency Matrix Aggregation
- Children Aggregation
- Date Histogram Aggregation
- Date Range Aggregation
- Diversified Sampler Aggregation
- Filter Aggregation
- Filters Aggregation
- Geo Distance Aggregation
- GeoHash grid Aggregation
- Global Aggregation
- Histogram Aggregation
- IP Range Aggregation
- Missing Aggregation
- Nested Aggregation
- Range Aggregation
- Reverse nested Aggregation
- Sampler Aggregation
- Significant Terms Aggregation
- Terms Aggregation
- Pipeline Aggregations
- Avg Bucket Aggregation
- Derivative Aggregation
- Max Bucket Aggregation
- Min Bucket Aggregation
- Sum Bucket Aggregation
- Stats Bucket Aggregation
- Extended Stats Bucket Aggregation
- Percentiles Bucket Aggregation
- Moving Average Aggregation
- Cumulative Sum Aggregation
- Bucket Script Aggregation
- Bucket Selector Aggregation
- Serial Differencing Aggregation
- Matrix Aggregations
- Caching heavy aggregations
- Returning only aggregation results
- Aggregation Metadata
- Returning the type of the aggregation
- Metrics Aggregations
- Indices APIs
- Create Index
- Delete Index
- Get Index
- Indices Exists
- Open / Close Index API
- Shrink Index
- Rollover Index
- Put Mapping
- Get Mapping
- Get Field Mapping
- Types Exists
- Index Aliases
- Update Indices Settings
- Get Settings
- Analyze
- Index Templates
- Shadow replica indices
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- Indices Segments
- Indices Recovery
- Indices Shard Stores
- Clear Cache
- Flush
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- Force Merge
- cat APIs
- Cluster APIs
- Query DSL
- Mapping
- Analysis
- Anatomy of an analyzer
- Testing analyzers
- Analyzers
- Normalizers
- Tokenizers
- Token Filters
- Standard Token Filter
- ASCII Folding Token Filter
- Flatten Graph 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
- Word Delimiter Graph 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
- Synonym Graph Token Filter
- Compound Word Token Filters
- 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
- Decimal Digit Token Filter
- Fingerprint Token Filter
- Minhash Token Filter
- Character Filters
- Modules
- Index Modules
- Ingest Node
- Pipeline Definition
- Ingest APIs
- Accessing Data in Pipelines
- Handling Failures in Pipelines
- Processors
- Append Processor
- Convert Processor
- Date Processor
- Date Index Name Processor
- Fail Processor
- Foreach Processor
- Grok Processor
- Gsub Processor
- Join Processor
- JSON Processor
- KV Processor
- Lowercase Processor
- Remove Processor
- Rename Processor
- Script Processor
- Set Processor
- Split Processor
- Sort Processor
- Trim Processor
- Uppercase Processor
- Dot Expander Processor
- X-Pack APIs
- Info API
- Explore API
- Machine Learning APIs
- Close Jobs
- Create Datafeeds
- Create Jobs
- Delete Datafeeds
- Delete Jobs
- Delete Model Snapshots
- Flush Jobs
- Get Buckets
- Get Categories
- Get Datafeeds
- Get Datafeed Statistics
- Get Influencers
- Get Jobs
- Get Job Statistics
- Get Model Snapshots
- Get Records
- Open Jobs
- Post Data to Jobs
- Preview Datafeeds
- Revert Model Snapshots
- Start Datafeeds
- Stop Datafeeds
- Update Datafeeds
- Update Jobs
- Update Model Snapshots
- Security APIs
- Watcher APIs
- Migration APIs
- Deprecation Info APIs
- Definitions
- X-Pack Commands
- How To
- Testing
- Glossary of terms
- Release Notes
- 5.6.16 Release Notes
- 5.6.15 Release Notes
- 5.6.14 Release Notes
- 5.6.13 Release Notes
- 5.6.12 Release Notes
- 5.6.11 Release Notes
- 5.6.10 Release Notes
- 5.6.9 Release Notes
- 5.6.8 Release Notes
- 5.6.7 Release Notes
- 5.6.6 Release Notes
- 5.6.5 Release Notes
- 5.6.4 Release Notes
- 5.6.3 Release Notes
- 5.6.2 Release Notes
- 5.6.1 Release Notes
- 5.6.0 Release Notes
- 5.5.3 Release Notes
- 5.5.2 Release Notes
- 5.5.1 Release Notes
- 5.5.0 Release Notes
- 5.4.3 Release Notes
- 5.4.2 Release Notes
- 5.4.1 Release Notes
- 5.4.0 Release Notes
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- 5.3.2 Release Notes
- 5.3.1 Release Notes
- 5.3.0 Release Notes
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- 5.2.1 Release Notes
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- 5.1.2 Release Notes
- 5.1.1 Release Notes
- 5.1.0 Release Notes
- 5.0.2 Release Notes
- 5.0.1 Release Notes
- 5.0.0 Combined Release Notes
- 5.0.0 GA Release Notes
- 5.0.0-rc1 Release Notes
- 5.0.0-beta1 Release Notes
- 5.0.0-alpha5 Release Notes
- 5.0.0-alpha4 Release Notes
- 5.0.0-alpha3 Release Notes
- 5.0.0-alpha2 Release Notes
- 5.0.0-alpha1 Release Notes
- 5.0.0-alpha1 Release Notes (Changes previously released in 2.x)
WARNING: Version 5.6 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.
Pattern Tokenizer
editPattern Tokenizer
editThe pattern
tokenizer uses a regular expression to either split text into
terms whenever it matches a word separator, or to capture matching text as
terms.
The default pattern is \W+
, which splits text whenever it encounters
non-word characters.
Beware of Pathological Regular Expressions
The pattern tokenizer uses Java Regular Expressions.
A badly written regular expression could run very slowly or even throw a StackOverflowError and cause the node it is running on to exit suddenly.
Read more about pathological regular expressions and how to avoid them.
Example output
editPOST _analyze { "tokenizer": "pattern", "text": "The foo_bar_size's default is 5." }
The above sentence would produce the following terms:
[ The, foo_bar_size, s, default, is, 5 ]
Configuration
editThe pattern
tokenizer accepts the following parameters:
|
A Java regular expression, defaults to |
|
Java regular expression flags.
Flags should be pipe-separated, eg |
|
Which capture group to extract as tokens. Defaults to |
Example configuration
editIn this example, we configure the pattern
tokenizer to break text into
tokens when it encounters commas:
PUT my_index { "settings": { "analysis": { "analyzer": { "my_analyzer": { "tokenizer": "my_tokenizer" } }, "tokenizer": { "my_tokenizer": { "type": "pattern", "pattern": "," } } } } } POST my_index/_analyze { "analyzer": "my_analyzer", "text": "comma,separated,values" }
The above example produces the following terms:
[ comma, separated, values ]
In the next example, we configure the pattern
tokenizer to capture values
enclosed in double quotes (ignoring embedded escaped quotes \"
). The regex
itself looks like this:
"((?:\\"|[^"]|\\")*)"
And reads as follows:
-
A literal
"
-
Start capturing:
-
A literal
\"
OR any character except"
- Repeat until no more characters match
-
A literal
-
A literal closing
"
When the pattern is specified in JSON, the "
and \
characters need to be
escaped, so the pattern ends up looking like:
\"((?:\\\\\"|[^\"]|\\\\\")+)\"
PUT my_index { "settings": { "analysis": { "analyzer": { "my_analyzer": { "tokenizer": "my_tokenizer" } }, "tokenizer": { "my_tokenizer": { "type": "pattern", "pattern": "\"((?:\\\\\"|[^\"]|\\\\\")+)\"", "group": 1 } } } } } POST my_index/_analyze { "analyzer": "my_analyzer", "text": "\"value\", \"value with embedded \\\" quote\"" }
The above example produces the following two terms:
[ value, value with embedded \" quote ]
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