# Elasticsearch in Action - Roy Russo, Radu Gheorghe, Matthew Lee Hinman
Published: 2015-11-17 by Simon and Schuster
## Queries
There are different types of queries, which are sent as JSON to the `/_search` endpoint.
### `match` query
Match all documents.
Query string analyzed.
Input tokens are OR by default.
### `multi_match`
Query across multiple fields
### `prefix` query
Well, prefix search.
### `fuzzy` search
Multi letter changes (set by `fuzziness`)
### Term-level queries
This is for querying structured data. Structured fields are stored as is (not run through an analyzer)
- `term` query to match a single term
- `range` query to match a range
### Compound queries
Create more sophisticated queries.
- `bool` query
- `must` - must match, contributes to score
- `must_not` - must not match, no score
- `should` - not mandatory, but contributes to score
- `filter` - must match, no score
- `constant_score` query
- `function_score` query
- `boosting` query
- `dismax_query` (disjunction max) query
### Aggregations
- metric aggregations
- sum, min, max, average
- bucket aggregations
- pipeline aggregations
- work on the output from other aggregations
## Query examples
### `match` query
```json
{
"query": {
"match": {
"author": { #A The author field is now having inner properties defined
"query": "Joshua Schildt", #B provide your query here
"operator": "AND" #C The AND operator (default is OR)
}
}
}
}
```
### `multi_match` query
```json
{
"query": {
"multi_match": { #A Multi match query that searches across multiple fields
"query": "Java", #B The search words
"fields": ["title","synopsis"] #C Searching across two fields
}
}
}
```
### `fuzzy` query
```json
{
"query": {
"fuzzy": {#A Fuzzy query to support spelling mistakes
"title": {
"value": "kava",#B The incorrectly spelt criteria
"fuzziness": 1 #C Fuzziness 1 indicates one letter forgiveness
}
}
}
}
```
### Term-level queries
```json
GET books/_search
{
"query": {
"range": { #A Range query declaration
"amazon_rating": {#B Mention the range to match
"gte": 4.5,#C gte - greater than or equal to
"lte": 5 #D lte - less than or equal to
}
}
}
}
```
```json
{
"query": {
"range": { #A Range query declaration
"amazon_rating": {#B Mention the range to match
"gte": 4.5,#C gte - greater than or equal to
"lte": 5 #D lte - less than or equal to
}
}
}
}
```
### Compound-queries
```json
{
"query": {
"bool": { #A A boolean query
"must": [{# A must clause - the documents must match to the criteria
"match": { #A One of the queries - a match query
"author": "Joshua Bloch"
}
}]
}
}
}
```
```json
{
"query": {
"bool": {
"must": [{ #A Must query with two leaf queries
"match": {#B A match query finding books authored by Joshua
"author": "Joshua Bloch"
}
},
{
"match_phrase": {#C A second query searching for a phrase
"synopsis": "best Java programming books"
}
}]
}
}
}
```
### Aggregations
```json
{
"aggs": { #A Writing an aggregation query
"critical_patients": { #B User defined query output name
"sum": {#C The sum metric - sum of all the critical patients
"field": "critical" #D The field on which the aggregation is applied
}
}
}
}
```
Buckets:
```json
{
"size": 0,
"aggs": {
"critical_patients_as_histogram": {#A The user-defined name of the report
"histogram": {#B The type of the bucketing aggregation - histogram
"field": "critical",#C The field the aggregation applied on
"interval": 2500#D The bucket interval
}
}
}
}
```