* [DOCS] Fixes titles in Discover, Graph, & Install for consistency * [DOCS] More docs tweaks for consistency
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176 lines
7 KiB
Text
[[kuery-query]]
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=== Kibana Query Language
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In Kibana 6.3, we introduced a number of exciting experimental query language enhancements. These
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features are now available by default in 7.0. Out of the box, Kibana's query language now includes scripted field support and a
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simplified, easier to use syntax. If you have a Basic license or above, autocomplete functionality will also be enabled.
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==== Language syntax
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If you're familiar with Kibana's old Lucene query syntax, you should feel right at home with the new syntax. The basics
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stay the same, we've simply refined things to make the query language easier to use.
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`response:200` will match documents where the response field matches the value 200.
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Quotes around a search term will initiate a phrase search. For example, `message:"Quick brown fox"` will search
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for the phrase "quick brown fox" in the message field. Without the quotes, your query will get broken down into tokens via
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the message field's configured analyzer and will match documents that contain those tokens, regardless of the order in which
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they appear. This means documents with "quick brown fox" will match, but so will "quick fox brown". Remember to use quotes if you want
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to search for a phrase.
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The query parser will no longer split on whitespace. Multiple search terms must be separated by explicit
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boolean operators. Lucene will combine search terms with an `or` by default, so `response:200 extension:php` would
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become `response:200 or extension:php` in KQL. This will match documents where response matches 200, extension matches php, or both.
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Note that boolean operators are not case sensitive.
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We can make terms required by using `and`.
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`response:200 and extension:php` will match documents where response matches 200 and extension matches php.
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By default, `and` has a higher precedence than `or`.
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`response:200 and extension:php or extension:css` will match documents where response is 200 and extension is php OR documents where extension is css and response is anything.
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We can override the default precedence with grouping.
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`response:200 and (extension:php or extension:css)` will match documents where response is 200 and extension is either php or css.
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A shorthand exists that allows us to easily search a single field for multiple values.
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`response:(200 or 404)` searches for docs where the `response` field matches 200 or 404. We can also search for docs
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with multi-value fields that contain a list of terms, for example: `tags:(success and info and security)`
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Terms can be inverted by prefixing them with `not`.
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`not response:200` will match all documents where response is not 200.
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Entire groups can also be inverted.
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`response:200 and not (extension:php or extension:css)`
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Ranges are similar to lucene with a small syntactical difference.
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Instead of `bytes:>1000`, we omit the colon: `bytes > 1000`.
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`>, >=, <, <=` are all valid range operators.
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Exist queries are simple and do not require a special operator. `response:*` will find all docs where the response
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field exists.
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Wildcard queries are available. `machine.os:win*` would match docs where the machine.os field starts with "win", which
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would match values like "windows 7" and "windows 10".
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Wildcards also allow us to search multiple fields at once. This can come in handy when you have both `text` and `keyword`
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versions of a field. Let's say we have `machine.os` and `machine.os.keyword` fields and we want to check both for the term
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"windows 10". We can do it like this: `machine.os*:windows 10".
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[NOTE]
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============
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Terms without fields will be matched against the default field in your index settings. If a default field is not
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set these terms will be matched against all fields. For example, a query for `response:200` will search for the value 200
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in the response field, but a query for just `200` will search for 200 across all fields in your index.
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============
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==== Nested field support
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KQL supports querying on {ref}/nested.html[nested fields] through a special syntax. You can query nested fields in subtly different
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ways, depending on the results you want, so crafting nested queries requires extra thought.
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One main consideration is how to match parts of the nested query to the individual nested documents.
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There are two main approaches to take:
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* *Parts of the query may only match a single nested document.* This is what most users want when querying on a nested field.
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* *Parts of the query can match different nested documents.* This is how a regular object field works.
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Although generally less useful, there might be occasions where you want to query a nested field in this way.
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Let's take a look at the first approach. In the following document, `items` is a nested field. Each document in the nested
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field contains a name, stock, and category.
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[source,json]
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----------------------------------
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{
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"grocery_name": "Elastic Eats",
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"items": [
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{
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"name": "banana",
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"stock": "12",
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"category": "fruit"
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},
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{
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"name": "peach",
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"stock": "10",
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"category": "fruit"
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},
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{
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"name": "carrot",
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"stock": "9",
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"category": "vegetable"
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},
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{
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"name": "broccoli",
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"stock": "5",
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"category": "vegetable"
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}
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]
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}
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----------------------------------
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===== Match a single nested document
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To find stores that have more than 10 bananas in stock, you would write a query like this:
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`items:{ name:banana and stock > 10 }`
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`items` is the "nested path". Everything inside the curly braces (the "nested group") must match a single nested document.
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The following example returns no matches because no single nested document has bananas with a stock of 9.
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`items:{ name:banana and stock:9 }`
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==== Match different nested documents
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The subqueries in this example are in separate nested groups and can match different nested documents.
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`items:{ name:banana } and items:{ stock:9 }`
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`name:banana` matches the first document in the array and `stock:9` matches the third document in the array.
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==== Combine approaches
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You can combine these two approaches to create complex queries. What if you wanted to find a store with more than 10
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bananas that *also* stocks vegetables? You could do this:
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`items:{ name:banana and stock > 10 } and items:{ category:vegetable }`
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The first nested group (`name:banana and stock > 10`) must still match a single document, but the `category:vegetables`
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subquery can match a different nested document because it is in a separate group.
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==== Nested fields inside other nested fields
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KQL's syntax also supports nested fields inside of other nested fields—you simply have to specify the full path. Suppose you
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have a document where `level1` and `level2` are both nested fields:
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[source,json]
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----------------------------------
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{
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"level1": [
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{
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"level2": [
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{
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"prop1": "foo",
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"prop2": "bar"
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},
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{
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"prop1": "baz",
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"prop2": "qux"
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}
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]
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}
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]
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}
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----------------------------------
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You can match on a single nested document by specifying the full path:
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`level1.level2:{ prop1:foo and prop2:bar }`
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