Difference between revisions of "ElasticSearch Query DSL"
| Line 135: | Line 135: | ||
=== query_string === | === query_string === | ||
| + | |||
| + | Uses query parser in order to parse its content. | ||
| + | |||
| + | <pre>{ | ||
| + | "query_string" : { | ||
| + | "default_field" : "content", | ||
| + | "query" : "this AND that OR thus" | ||
| + | } | ||
| + | }</pre> | ||
| + | |||
| + | ==== Parameters ==== | ||
| + | |||
| + | * ''query'' - actual query to be parsed. | ||
| + | * ''default_field'' - default field for query terms (if no prefix field specified); default ''index.query.default_field'' settings, which defaults to ''_all'', | ||
| + | * ''fields'' - run query against multiple fields (provided as array): | ||
| + | ** <tt>"fields" : ["content", "name"]</tt>, | ||
| + | ** optionally with boosting: <tt>"fields" : ["content", "name^5"]</tt>, | ||
| + | ** wildcards may be used for fields: <tt>"fields" : ["city.*"]</tt> if document contains object ''city'', | ||
| + | ** to check for existence of nonexistence of fields, use: <tt>_exists_:field1</tt> and <tt>_missing_:field</tt>, | ||
| + | * ''default_operator'' - default operator used (if none explicitly specified); e.g. with default operator ''OR'', the query "capital of Hungary" is translated to "capital OR of OR Hungary"; default is ''OR'', | ||
| + | * ''allow_leading_wildcard'' - are '''*''' or '''?''' allowed as the first character? default ''true'', | ||
| + | * ''lowercase_expanded_terms'' - should terms of wildcard, prefix, fuzzy, and range queries be automatically lower-cased? (since they are not analyzed); default ''true'', | ||
| + | * ''boost'' - boost value of the query; default 1.0, | ||
| + | * ''minimum_should_match'' - percent value ("20%") controlling how many "should" clauses in the resulting boolean query should match, | ||
| + | * ''lenient'' - if true, format based failures (like providing text to a numeric field) to be ignored. | ||
=== range === | === range === | ||
Revision as of 12:40, 23 January 2013
ES's Query DSL is a language for specifying queries in JSON.
This is by far not an exhaustive documentation, it's just stuff I use the most; see official documentation for more. Especially the boosting and scoring functionality is not documented here to proper extent.
Contents
Queries
match, multi_match
The match queries accept, analyze, and construct query out of text/numeric/date. The match family of queries does not go through a "query parsing" process. It does not support field name prefixes, wildcard characters, or other "advance" features.
Here, message is name of the field to match in (can be also _all):
{
"match" : {
"message" : "this is a test"
}
}
By default, terms are OR'ed; to AND them:
{
"match" : {
"message" : {
"query" : "this is a test",
"operator" : "and"
}
}
}
To match a phrase:
{
"match_phrase" : {
"message" : "this is a test"
}
}
or using the last word as prefix (the "as you type" search):
{
"match_phrase_prefix" : {
"message" : "this is a test"
}
}
To match in multiple fields, with optional boosting, use:
{
"multi_match" : {
"query" : "this is a test",
"fields" : [ "subject^2", "message" ]
}
}
where matches in subject are "twice as important" as matched in message.
bool
The bool query provides a Boolean combination of queries with typed occurrence:
- must - clause must appear in matching documents,
- should - should appear; is no must clause is provided, at least one should clause must be matched; you can also specify minimum_number_should_match parameter,
- must_not appear.
{
"bool" : {
"must" : {
"term" : { "user" : "kimchy" }
},
"must_not" : {
"range" : {
"age" : { "from" : 10, "to" : 20 }
}
},
"should" : [
{
"term" : { "tag" : "wow" }
},
{
"term" : { "tag" : "elasticsearch" }
}
],
"minimum_number_should_match" : 1,
"boost" : 1.0
}
}
boosting
Boosting can be used to promote or demote search results:
{
"boosting" : {
"positive" : {
"term" : {
"field1" : "value1"
}
},
"negative" : {
"term" : {
"field2" : "value2"
}
},
"negative_boost" : 0.2
}
}
ids
Match by ID:
{
"ids" : {
"type" : "my_type",
"values" : ["1", "4", "100"]
}
}
Note: type field is optional, and may contain array of values.
field
Query only on a specified field (equivalent of query_string with default_field):
{
"field" : {
"name.first" : "+something -else"
}
}
filtered
Filters results of a query; may be much faster than querying, as no scoring is done, and may be cached:
{
"filtered" : {
"query" : {
"term" : { "tag" : "wow" }
},
"filter" : {
"range" : {
"age" : { "from" : 10, "to" : 20 }
}
}
}
}
query_string
Uses query parser in order to parse its content.
{
"query_string" : {
"default_field" : "content",
"query" : "this AND that OR thus"
}
}
Parameters
- query - actual query to be parsed.
- default_field - default field for query terms (if no prefix field specified); default index.query.default_field settings, which defaults to _all,
- fields - run query against multiple fields (provided as array):
- "fields" : ["content", "name"],
- optionally with boosting: "fields" : ["content", "name^5"],
- wildcards may be used for fields: "fields" : ["city.*"] if document contains object city,
- to check for existence of nonexistence of fields, use: _exists_:field1 and _missing_:field,
- default_operator - default operator used (if none explicitly specified); e.g. with default operator OR, the query "capital of Hungary" is translated to "capital OR of OR Hungary"; default is OR,
- allow_leading_wildcard - are * or ? allowed as the first character? default true,
- lowercase_expanded_terms - should terms of wildcard, prefix, fuzzy, and range queries be automatically lower-cased? (since they are not analyzed); default true,
- boost - boost value of the query; default 1.0,
- minimum_should_match - percent value ("20%") controlling how many "should" clauses in the resulting boolean query should match,
- lenient - if true, format based failures (like providing text to a numeric field) to be ignored.
