- Elasticsearch Guide: other versions:
- What is Elasticsearch?
- What’s new in 7.10
- Getting started with Elasticsearch
- Set up Elasticsearch
- Installing Elasticsearch
- Configuring Elasticsearch
- Setting JVM options
- Secure settings
- Auditing settings
- Circuit breaker settings
- Cluster-level shard allocation and routing settings
- Cross-cluster replication settings
- Discovery and cluster formation settings
- Field data cache settings
- HTTP
- Index lifecycle management settings
- Index management settings
- Index recovery settings
- Indexing buffer settings
- License settings
- Local gateway settings
- Logging
- Machine learning settings
- Monitoring settings
- Node
- Network settings
- Node query cache settings
- Search settings
- Security settings
- Shard request cache settings
- Snapshot lifecycle management settings
- Transforms settings
- Transport
- Thread pools
- Watcher settings
- Important Elasticsearch configuration
- Important System Configuration
- 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
- All permission check
- Discovery configuration check
- Bootstrap Checks for X-Pack
- Starting Elasticsearch
- Stopping Elasticsearch
- Discovery and cluster formation
- Add and remove nodes in your cluster
- Full-cluster restart and rolling restart
- Remote clusters
- Set up X-Pack
- Configuring X-Pack Java Clients
- Plugins
- Upgrade Elasticsearch
- Index modules
- Mapping
- Text analysis
- Overview
- Concepts
- Configure text analysis
- Built-in analyzer reference
- Tokenizer reference
- Token filter reference
- Apostrophe
- ASCII folding
- CJK bigram
- CJK width
- Classic
- Common grams
- Conditional
- Decimal digit
- Delimited payload
- Dictionary decompounder
- Edge n-gram
- Elision
- Fingerprint
- Flatten graph
- Hunspell
- Hyphenation decompounder
- Keep types
- Keep words
- Keyword marker
- Keyword repeat
- KStem
- Length
- Limit token count
- Lowercase
- MinHash
- Multiplexer
- N-gram
- Normalization
- Pattern capture
- Pattern replace
- Phonetic
- Porter stem
- Predicate script
- Remove duplicates
- Reverse
- Shingle
- Snowball
- Stemmer
- Stemmer override
- Stop
- Synonym
- Synonym graph
- Trim
- Truncate
- Unique
- Uppercase
- Word delimiter
- Word delimiter graph
- Character filters reference
- Normalizers
- Index templates
- Data streams
- Ingest node
- Search your data
- Query DSL
- Aggregations
- Bucket aggregations
- Adjacency matrix
- Auto-interval date histogram
- Children
- Composite
- Date histogram
- Date range
- Diversified sampler
- Filter
- Filters
- Geo-distance
- Geohash grid
- Geotile grid
- Global
- Histogram
- IP range
- Missing
- Nested
- Parent
- Range
- Rare terms
- Reverse nested
- Sampler
- Significant terms
- Significant text
- Terms
- Variable width histogram
- Subtleties of bucketing range fields
- Metrics aggregations
- Pipeline aggregations
- Bucket aggregations
- EQL
- SQL access
- Overview
- Getting Started with SQL
- Conventions and Terminology
- Security
- SQL REST API
- SQL Translate API
- SQL CLI
- SQL JDBC
- SQL ODBC
- SQL Client Applications
- SQL Language
- Functions and Operators
- Comparison Operators
- Logical Operators
- Math Operators
- Cast Operators
- LIKE and RLIKE Operators
- Aggregate Functions
- Grouping Functions
- Date/Time and Interval Functions and Operators
- Full-Text Search Functions
- Mathematical Functions
- String Functions
- Type Conversion Functions
- Geo Functions
- Conditional Functions And Expressions
- System Functions
- Reserved keywords
- SQL Limitations
- Scripting
- Data management
- ILM: Manage the index lifecycle
- Overview
- Concepts
- Automate rollover
- Manage Filebeat time-based indices
- Index lifecycle actions
- Configure a lifecycle policy
- Migrate index allocation filters to node roles
- Resolve lifecycle policy execution errors
- Start and stop index lifecycle management
- Manage existing indices
- Skip rollover
- Restore a managed data stream or index
- Monitor a cluster
- Frozen indices
- Roll up or transform your data
- Set up a cluster for high availability
- Snapshot and restore
- Secure a cluster
- Overview
- Configuring security
- User authentication
- Built-in users
- Internal users
- Token-based authentication services
- Realms
- Realm chains
- Active Directory user authentication
- File-based user authentication
- LDAP user authentication
- Native user authentication
- OpenID Connect authentication
- PKI user authentication
- SAML authentication
- Kerberos authentication
- Integrating with other authentication systems
- Enabling anonymous access
- Controlling the user cache
- Configuring SAML single-sign-on on the Elastic Stack
- Configuring single sign-on to the Elastic Stack using OpenID Connect
- User authorization
- Built-in roles
- Defining roles
- Granting access to Stack Management features
- Security privileges
- Document level security
- Field level security
- Granting privileges for data streams and index aliases
- Mapping users and groups to roles
- Setting up field and document level security
- Submitting requests on behalf of other users
- Configuring authorization delegation
- Customizing roles and authorization
- Enabling audit logging
- Encrypting communications
- Restricting connections with IP filtering
- Cross cluster search, clients, and integrations
- Tutorial: Getting started with security
- Tutorial: Encrypting communications
- Troubleshooting
- Some settings are not returned via the nodes settings API
- Authorization exceptions
- Users command fails due to extra arguments
- Users are frequently locked out of Active Directory
- Certificate verification fails for curl on Mac
- SSLHandshakeException causes connections to fail
- Common SSL/TLS exceptions
- Common Kerberos exceptions
- Common SAML issues
- Internal Server Error in Kibana
- Setup-passwords command fails due to connection failure
- Failures due to relocation of the configuration files
- Limitations
- Watch for cluster and index events
- Command line tools
- How To
- Glossary of terms
- REST APIs
- API conventions
- Compact and aligned text (CAT) APIs
- cat aliases
- cat allocation
- cat anomaly detectors
- cat count
- cat data frame analytics
- cat datafeeds
- cat fielddata
- cat health
- cat indices
- cat master
- cat nodeattrs
- cat nodes
- cat pending tasks
- cat plugins
- cat recovery
- cat repositories
- cat segments
- cat shards
- cat snapshots
- cat task management
- cat templates
- cat thread pool
- cat trained model
- cat transforms
- Cluster APIs
- Cluster allocation explain
- Cluster get settings
- Cluster health
- Cluster reroute
- Cluster state
- Cluster stats
- Cluster update settings
- Nodes feature usage
- Nodes hot threads
- Nodes info
- Nodes reload secure settings
- Nodes stats
- Pending cluster tasks
- Remote cluster info
- Task management
- Voting configuration exclusions
- Cross-cluster replication APIs
- Data stream APIs
- Document APIs
- Enrich APIs
- Graph explore API
- Index APIs
- Add index alias
- Analyze
- Clear cache
- Clone index
- Close index
- Create index
- Delete index
- Delete index alias
- Delete component template
- Delete index template
- Delete index template (legacy)
- Flush
- Force merge
- Freeze index
- Get component template
- Get field mapping
- Get index
- Get index alias
- Get index settings
- Get index template
- Get index template (legacy)
- Get mapping
- Index alias exists
- Index exists
- Index recovery
- Index segments
- Index shard stores
- Index stats
- Index template exists (legacy)
- Open index
- Put index template
- Put index template (legacy)
- Put component template
- Put mapping
- Refresh
- Rollover index
- Shrink index
- Simulate index
- Simulate template
- Split index
- Synced flush
- Type exists
- Unfreeze index
- Update index alias
- Update index settings
- Resolve index
- List dangling indices
- Import dangling index
- Delete dangling index
- Index lifecycle management APIs
- Ingest APIs
- Info API
- Licensing APIs
- Machine learning anomaly detection APIs
- Add events to calendar
- Add jobs to calendar
- Close jobs
- Create jobs
- Create calendars
- Create datafeeds
- Create filters
- Delete calendars
- Delete datafeeds
- Delete events from calendar
- Delete filters
- Delete forecasts
- Delete jobs
- Delete jobs from calendar
- Delete model snapshots
- Delete expired data
- Estimate model memory
- Find file structure
- Flush jobs
- Forecast jobs
- Get buckets
- Get calendars
- Get categories
- Get datafeeds
- Get datafeed statistics
- Get influencers
- Get jobs
- Get job statistics
- Get machine learning info
- Get model snapshots
- Get overall buckets
- Get scheduled events
- Get filters
- Get records
- Open jobs
- Post data to jobs
- Preview datafeeds
- Revert model snapshots
- Set upgrade mode
- Start datafeeds
- Stop datafeeds
- Update datafeeds
- Update filters
- Update jobs
- Update model snapshots
- Machine learning data frame analytics APIs
- Create data frame analytics jobs
- Create trained models
- Update data frame analytics jobs
- Delete data frame analytics jobs
- Delete trained models
- Evaluate data frame analytics
- Explain data frame analytics
- Get data frame analytics jobs
- Get data frame analytics jobs stats
- Get trained models
- Get trained models stats
- Start data frame analytics jobs
- Stop data frame analytics jobs
- Migration APIs
- Reload search analyzers API
- Repositories metering APIs
- Rollup APIs
- Search APIs
- Searchable snapshots APIs
- Security APIs
- Authenticate
- Change passwords
- Clear cache
- Clear roles cache
- Clear privileges cache
- Clear API key cache
- Create API keys
- Create or update application privileges
- Create or update role mappings
- Create or update roles
- Create or update users
- Delegate PKI authentication
- Delete application privileges
- Delete role mappings
- Delete roles
- Delete users
- Disable users
- Enable users
- Get API key information
- Get application privileges
- Get builtin privileges
- Get role mappings
- Get roles
- Get token
- Get users
- Grant API keys
- Has privileges
- Invalidate API key
- Invalidate token
- OpenID Connect prepare authentication
- OpenID Connect authenticate
- OpenID Connect logout
- SAML prepare authentication
- SAML authenticate
- SAML logout
- SAML invalidate
- SSL certificate
- Snapshot and restore APIs
- Snapshot lifecycle management APIs
- Transform APIs
- Usage API
- Watcher APIs
- Definitions
- Migration guide
- Release notes
- Elasticsearch version 7.10.2
- Elasticsearch version 7.10.1
- Elasticsearch version 7.10.0
- Elasticsearch version 7.9.3
- Elasticsearch version 7.9.2
- Elasticsearch version 7.9.1
- Elasticsearch version 7.9.0
- Elasticsearch version 7.8.1
- Elasticsearch version 7.8.0
- Elasticsearch version 7.7.1
- Elasticsearch version 7.7.0
- Elasticsearch version 7.6.2
- Elasticsearch version 7.6.1
- Elasticsearch version 7.6.0
- Elasticsearch version 7.5.2
- Elasticsearch version 7.5.1
- Elasticsearch version 7.5.0
- Elasticsearch version 7.4.2
- Elasticsearch version 7.4.1
- Elasticsearch version 7.4.0
- Elasticsearch version 7.3.2
- Elasticsearch version 7.3.1
- Elasticsearch version 7.3.0
- Elasticsearch version 7.2.1
- Elasticsearch version 7.2.0
- Elasticsearch version 7.1.1
- Elasticsearch version 7.1.0
- Elasticsearch version 7.0.0
- Elasticsearch version 7.0.0-rc2
- Elasticsearch version 7.0.0-rc1
- Elasticsearch version 7.0.0-beta1
- Elasticsearch version 7.0.0-alpha2
- Elasticsearch version 7.0.0-alpha1
- Dependencies and versions
Lexical Structure
editLexical Structure
editThis section covers the major lexical structure of SQL, which for the most part, is going to resemble that of ANSI SQL itself hence why low-levels details are not discussed in depth.
Elasticsearch SQL currently accepts only one command at a time. A command is a sequence of tokens terminated by the end of input stream.
A token can be a key word, an identifier (quoted or unquoted), a literal (or constant) or a special character symbol (typically a delimiter). Tokens are typically separated by whitespace (be it space, tab) though in some cases, where there is no ambiguity (typically due to a character symbol) this is not needed - however for readability purposes this should be avoided.
Key Words
editTake the following example:
SELECT * FROM table
This query has four tokens: SELECT
, *
, FROM
and table
. The first three, namely SELECT
, *
and FROM
are key words meaning words that have a fixed meaning in SQL. The token table
is an identifier meaning it identifies (by name) an entity inside SQL such as a table (in this case), a column, etc…
As one can see, both key words and identifiers have the same lexical structure and thus one cannot know whether a token is one or the other without knowing the SQL language; the complete list of key words is available in the reserved appendix. Do note that key words are case-insensitive meaning the previous example can be written as:
select * fRoM table;
Identifiers however are not - as Elasticsearch is case sensitive, Elasticsearch SQL uses the received value verbatim.
To help differentiate between the two, through-out the documentation the SQL key words are upper-cased a convention we find increases readability and thus recommend to others.
Identifiers
editIdentifiers can be of two types: quoted and unquoted:
SELECT ip_address FROM "hosts-*"
This query has two identifiers, ip_address
and hosts-*
(an index pattern). As ip_address
does not clash with any key words it can be used verbatim, hosts-*
on the other hand cannot as it clashes with -
(minus operation) and *
hence the double quotes.
Another example:
SELECT "from" FROM "<logstash-{now/d}>"
The first identifier from needs to quoted as otherwise it clashes with the FROM
key word (which is case insensitive as thus can be written as from
) while the second identifier using Elasticsearch Date math support in index names would have otherwise confuse the parser.
Hence why in general, especially when dealing with user input it is highly recommended to use quotes for identifiers. It adds minimal increase to your queries and in return offers clarity and disambiguation.
Literals (Constants)
editElasticsearch SQL supports two kind of implicitly-typed literals: strings and numbers.
String Literals
editA string literal is an arbitrary number of characters bounded by single quotes '
: 'Giant Robot'
.
To include a single quote in the string, escape it using another single quote: 'Captain EO''s Voyage'
.
An escaped single quote is not a double quote ("
), but a single quote '
repeated (''
).
Numeric Literals
editNumeric literals are accepted both in decimal and scientific notation with exponent marker (e
or E
), starting either with a digit or decimal point .
:
1969 -- integer notation 3.14 -- decimal notation .1234 -- decimal notation starting with decimal point 4E5 -- scientific notation (with exponent marker) 1.2e-3 -- scientific notation with decimal point
Numeric literals that contain a decimal point are always interpreted as being of type double
. Those without are considered integer
if they fit otherwise their type is long
(or BIGINT
in ANSI SQL types).
Generic Literals
editWhen dealing with arbitrary type literal, one creates the object by casting, typically, the string representation to the desired type. This can be achieved through the dedicated cast operator and functions:
123::LONG -- cast 123 to a LONG CAST('1969-05-13T12:34:56' AS TIMESTAMP) -- cast the given string to datetime CONVERT('10.0.0.1', IP) -- cast '10.0.0.1' to an IP
Do note that Elasticsearch SQL provides functions that out of the box return popular literals (like E()
) or provide dedicated parsing for certain strings.
Single vs Double Quotes
editIt is worth pointing out that in SQL, single quotes '
and double quotes "
have different meaning and cannot be used interchangeably.
Single quotes are used to declare a string literal while double quotes for identifiers.
To wit:
To escape single or double quotes, one needs to use that specific quote one more time. For example, the literal John's
can be escaped like
SELECT 'John''s' AS name
. The same goes for double quotes escaping - SELECT 123 AS "test""number"
will display as a result a column with the name test"number
.
Special characters
editA few characters that are not alphanumeric have a dedicated meaning different from that of an operator. For completeness these are specified below:
Char |
Description |
|
The asterisk (or wildcard) is used in some contexts to denote all fields for a table. Can be also used as an argument to some aggregate functions. |
|
Commas are used to enumerate the elements of a list. |
|
Used in numeric constants or to separate identifiers qualifiers (catalog, table, column names, etc…). |
|
Parentheses are used for specific SQL commands, function declarations or to enforce precedence. |
Operators
editMost operators in Elasticsearch SQL have the same precedence and are left-associative. As this is done at parsing time, parenthesis need to be used to enforce a different precedence.
The following table indicates the supported operators and their precedence (highest to lowest);
Operator/Element |
Associativity |
Description |
|
left |
qualifier separator |
|
left |
PostgreSQL-style type cast |
|
right |
unary plus and minus (numeric literal sign) |
|
left |
multiplication, division, modulo |
|
left |
addition, subtraction |
|
range containment, string matching |
|
|
comparison |
|
|
right |
logical negation |
|
left |
logical conjunction |
|
left |
logical disjunction |
Comments
editElasticsearch SQL allows comments which are sequence of characters ignored by the parsers.
Two styles are supported:
- Single Line
-
Comments start with a double dash
--
and continue until the end of the line. - Multi line
-
Comments that start with
/*
and end with*/
(also known as C-style).
-- single line comment /* multi line comment that supports /* nested comments */ */
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