[[query-dsl-simple-query-string-query]]
=== Simple Query String Query

A query that uses the SimpleQueryParser to parse its context. Unlike the
regular `query_string` query, the `simple_query_string` query will never
throw an exception, and discards invalid parts of the query. Here is
an example:

[source,js]
--------------------------------------------------
{
    "simple_query_string" : {
        "query": "\"fried eggs\" +(eggplant | potato) -frittata",
        "analyzer": "snowball",
        "fields": ["body^5","_all"],
        "default_operator": "and"
    }
}
--------------------------------------------------

The `simple_query_string` top level parameters include:

[cols="<,<",options="header",]
|=======================================================================
|Parameter |Description
|`query` |The actual query to be parsed. See below for syntax.

|`fields` |The fields to perform the parsed query against. Defaults to the
`index.query.default_field` index settings, which in turn defaults to `_all`.

|`default_operator` |The default operator used if no explicit operator
is specified. For example, with a default operator of `OR`, the query
`capital of Hungary` is translated to `capital OR of OR Hungary`, and
with default operator of `AND`, the same query is translated to
`capital AND of AND Hungary`. The default value is `OR`.

|`analyzer` |The analyzer used to analyze each term of the query when
creating composite queries.

|`flags` |Flags specifying which features of the `simple_query_string` to
enable. Defaults to `ALL`.

|`lowercase_expanded_terms` | Whether terms of prefix and fuzzy queries are to
be automatically lower-cased or not (since they are not analyzed). Defaults to
true.
|=======================================================================

[float]
==== Simple Query String Syntax
The `simple_query_string` supports the following special characters:

* `+` signifies AND operation
* `|` signifies OR operation
* `-` negates a single token
* `"` wraps a number of tokens to signify a phrase for searching
* `*` at the end of a term signifies a prefix query
* `(` and `)` signify precedence
* `~N` after a word signifies edit distance (fuzziness)
* `~N` after a phrase signifies slop amount

In order to search for any of these special characters, they will need to
be escaped with `\`.

[float]
==== Default Field
When not explicitly specifying the field to search on in the query
string syntax, the `index.query.default_field` will be used to derive
which field to search on. It defaults to `_all` field.

So, if `_all` field is disabled, it might make sense to change it to set
a different default field.

[float]
==== Multi Field
The fields parameter can also include pattern based field names,
allowing to automatically expand to the relevant fields (dynamically
introduced fields included). For example:

[source,js]
--------------------------------------------------
{
    "simple_query_string" : {
        "fields" : ["content", "name.*^5"],
        "query" : "foo bar baz"
    }
}
--------------------------------------------------

[float]
==== Flags
`simple_query_string` support multiple flags to specify which parsing features
should be enabled. It is specified as a `|`-delimited string with the
`flags` parameter:

[source,js]
--------------------------------------------------
{
    "simple_query_string" : {
        "query" : "foo | bar  & baz*",
        "flags" : "OR|AND|PREFIX"
    }
}
--------------------------------------------------

The available flags are: `ALL`, `NONE`, `AND`, `OR`, `PREFIX`, `PHRASE`,
`PRECEDENCE`, `ESCAPE`, `WHITESPACE`, `FUZZY`, `NEAR`, and `SLOP`.
