Common Query Parameters | Apache Solr Reference Guide 7.2

Several query parsers share supported query parameters.

The following sections describe Solr’s common query parameters, which are supported by the Search RequestHandlers.

defType Parameter

The defType parameter selects the query parser that Solr should use to process the main query parameter (q) in the request. For example:

defType=dismax

If no defType param is specified, then by default, the The Standard Query Parser is used. (e.g., defType=lucene)

sort Parameter

The sort parameter arranges search results in either ascending (asc) or descending (desc) order. The parameter can be used with either numerical or alphabetical content. The directions can be entered in either all lowercase or all uppercase letters (i.e., both asc or ASC).

Solr can sort query responses according to document scores or the value of any field with a single value that is either indexed or uses DocValues (that is, any field whose attributes in the Schema include multiValued="false" and either docValues="true" or indexed="true" – if the field does not have DocValues enabled, the indexed terms are used to build them on the fly at runtime), provided that:

the field is non-tokenized (that is, the field has no analyzer and its contents have been parsed into tokens, which would make the sorting inconsistent), or
the field uses an analyzer (such as the KeywordTokenizer) that produces only a single term.

If you want to be able to sort on a field whose contents you want to tokenize to facilitate searching, use a copyField directive in the the Schema to clone the field. Then search on the field and sort on its clone.

The table explains how Solr responds to various settings of the sort parameter.

Example Result

Example	Result
	If the sort parameter is omitted, sorting is performed as though the parameter were set to score `desc`.
score desc	Sorts in descending order from the highest score to the lowest score.
price asc	Sorts in ascending order of the price field
inStock desc, price asc	Sorts by the contents of the `inStock` field in descending order, then within those results sorts in ascending order by the contents of the price field.

If the sort parameter is omitted, sorting is performed as though the parameter were set to score desc.

score desc

Sorts in descending order from the highest score to the lowest score.

price asc

Sorts in ascending order of the price field

inStock desc, price asc

Sorts by the contents of the inStock field in descending order, then within those results sorts in ascending order by the contents of the price field.

Regarding the sort parameter’s arguments:

A sort ordering must include a field name (or score as a pseudo field), followed by whitespace (escaped as + or %20 in URL strings), followed by a sort direction (asc or desc).
Multiple sort orderings can be separated by a comma, using this syntax: sort=<field name><direction>,<field name><direction>],…
- When more than one sort criteria is provided, the second entry will only be used if the first entry results in a tie. If there is a third entry, it will only be used if the first AND second entries are tied. This pattern continues with further entries.

start Parameter

When specified, the start parameter specifies an offset into a query’s result set and instructs Solr to begin displaying results from this offset.

The default value is 0. In other words, by default, Solr returns results without an offset, beginning where the results themselves begin.

Setting the start parameter to some other number, such as 3, causes Solr to skip over the preceding records and start at the document identified by the offset.

You can use the start parameter this way for paging. For example, if the rows parameter is set to 10, you could display three successive pages of results by setting start to 0, then re-issuing the same query and setting start to 10, then issuing the query again and setting start to 20.

rows Parameter

You can use the rows parameter to paginate results from a query. The parameter specifies the maximum number of documents from the complete result set that Solr should return to the client at one time.

The default value is 10. That is, by default, Solr returns 10 documents at a time in response to a query.

fq (Filter Query) Parameter

The fq parameter defines a query that can be used to restrict the superset of documents that can be returned, without influencing score. It can be very useful for speeding up complex queries, since the queries specified with fq are cached independently of the main query. When a later query uses the same filter, there’s a cache hit, and filter results are returned quickly from the cache.

When using the fq parameter, keep in mind the following:

The fq parameter can be specified multiple times in a query. Documents will only be included in the result if they are in the intersection of the document sets resulting from each instance of the parameter. In the example below, only documents which have a popularity greater then 10 and have a section of 0 will match.
```
fq=popularity:[10 TO *]&fq=section:0
```
Filter queries can involve complicated Boolean queries. The above example could also be written as a single fq with two mandatory clauses like so:
```
fq=+popularity:[10 TO *] +section:0
```
The document sets from each filter query are cached independently. Thus, concerning the previous examples: use a single fq containing two mandatory clauses if those clauses appear together often, and use two separate fq parameters if they are relatively independent. (To learn about tuning cache sizes and making sure a filter cache actually exists, see The Well-Configured Solr Instance.)
It is also possible to use filter(condition) syntax inside the fq to cache clauses individually and - among other things - to achieve union of cached filter queries.
As with all parameters: special characters in an URL need to be properly escaped and encoded as hex values. Online tools are available to help you with URL-encoding. For example: http://meyerweb.com/eric/tools/dencoder/.

fl (Field List) Parameter

The fl parameter limits the information included in a query response to a specified list of fields. The fields must be either stored="true" or docValues="true"`.`

The field list can be specified as a space-separated or comma-separated list of field names. The string "score" can be used to indicate that the score of each document for the particular query should be returned as a field. The wildcard character * selects all the fields in the document which are either stored="true" or docValues="true" and useDocValuesAsStored="true" (which is the default when docValues are enabled). You can also add pseudo-fields, functions and transformers to the field list request.

This table shows some basic examples of how to use fl:

Field List Result

Field List	Result
id name price	Return only the id, name, and price fields.
id,name,price	Return only the id, name, and price fields.
id name, price	Return only the id, name, and price fields.
id score	Return the id field and the score.
*	Return all the `stored` fields in each document, as well as any `docValues` fields that have `useDocValuesAsStored="true"`. This is the default value of the fl parameter.
* score	Return all the fields in each document, along with each field’s score.
*,dv_field_name	Return all the `stored` fields in each document, and any `docValues` fields that have `useDocValuesAsStored="true"` and the docValues from dv_field_name even if it has `useDocValuesAsStored="false"`

id name price

Return only the id, name, and price fields.

id,name,price

Return only the id, name, and price fields.

id name, price

Return only the id, name, and price fields.

id score

Return the id field and the score.

Return all the stored fields in each document, as well as any docValues fields that have useDocValuesAsStored="true". This is the default value of the fl parameter.

* score

Return all the fields in each document, along with each field’s score.

*,dv_field_name

Return all the stored fields in each document, and any docValues fields that have useDocValuesAsStored="true" and the docValues from dv_field_name even if it has useDocValuesAsStored="false"

Functions with fl

Functions can be computed for each document in the result and returned as a pseudo-field:

fl=id,title,product(price,popularity)

Document Transformers with fl

Document Transformers can be used to modify the information returned about each documents in the results of a query:

fl=id,title,[explain]

Field Name Aliases

You can change the key used to in the response for a field, function, or transformer by prefixing it with a `"displayName:`". For example:

fl=id,sales_price:price,secret_sauce:prod(price,popularity),why_score:[explain style=nl]

{
"response": {
    "numFound": 2,
    "start": 0,
    "docs": [{
        "id": "6H500F0",
        "secret_sauce": 2100.0,
        "sales_price": 350.0,
        "why_score": {
            "match": true,
            "value": 1.052226,
            "description": "weight(features:cache in 2) [DefaultSimilarity], result of:",
            "details": [{
                "..."
}]}}]}}

debug Parameter

The debug parameter can be specified multiple times and supports the following arguments:

debug=query: return debug information about the query only.
debug=timing: return debug information about how long the query took to process.
debug=results: return debug information about the score results (also known as "explain").
- By default, score explanations are returned as large string values, using newlines and tab indenting for structure & readability, but an additional debug.explain.structured=true parameter may be specified to return this information as nested data structures native to the response format requested by wt.
debug=all: return all available debug information about the request request. (alternatively usage: debug=true)

For backwards compatibility with older versions of Solr, debugQuery=true may instead be specified as an alternative way to indicate debug=all

The default behavior is not to include debugging information.

explainOther Parameter

The explainOther parameter specifies a Lucene query in order to identify a set of documents. If this parameter is included and is set to a non-blank value, the query will return debugging information, along with the "explain info" of each document that matches the Lucene query, relative to the main query (which is specified by the q parameter). For example:

q=supervillians&debugQuery=on&explainOther=id:juggernaut

The query above allows you to examine the scoring explain info of the top matching documents, compare it to the explain info for documents matching id:juggernaut, and determine why the rankings are not as you expect.

The default value of this parameter is blank, which causes no extra "explain info" to be returned.

timeAllowed Parameter

This parameter specifies the amount of time, in milliseconds, allowed for a search to complete. If this time expires before the search is complete, any partial results will be returned, but values such as numFound, facet counts, and result stats may not be accurate for the entire result set.

This value is only checked at the time of:

Query Expansion, and
Document collection

As this check is periodically performed, the actual time for which a request can be processed before it is aborted would be marginally greater than or equal to the value of timeAllowed. If the request consumes more time in other stages, custom components, etc., this parameter is not expected to abort the request.

segmentTerminateEarly Parameter

This parameter may be set to either true or false.

If set to true, and if the mergePolicyFactory for this collection is a SortingMergePolicyFactory which uses a sort option compatible with the sort parameter specified for this query, then Solr will attempt to use an EarlyTerminatingSortingCollector.

If early termination is used, a segmentTerminatedEarly header will be included in the responseHeader.

Similar to using the timeAllowed Parameter, when early segment termination happens values such as numFound, Facet counts, and result Stats may not be accurate for the entire result set.

The default value of this parameter is false.

omitHeader Parameter

This parameter may be set to either true or false.

If set to true, this parameter excludes the header from the returned results. The header contains information about the request, such as the time it took to complete. The default value for this parameter is false.

wt Parameter

The wt parameter selects the Response Writer that Solr should use to format the query’s response. For detailed descriptions of Response Writers, see Response Writers.

If you do not define the wt parameter in your queries, JSON will be returned as the format of the response.

cache Parameter

Solr caches the results of all queries and filter queries by default. To disable result caching, set the cache=false parameter.

You can also use the cost option to control the order in which non-cached filter queries are evaluated. This allows you to order less expensive non-cached filters before expensive non-cached filters.

For very high cost filters, if cache=false and cost>=100 and the query implements the PostFilter interface, a Collector will be requested from that query and used to filter documents after they have matched the main query and all other filter queries. There can be multiple post filters; they are also ordered by cost.

For most queries the default behavior is cost=0 — but some types of queries such as {!frange} default to cost=100, because they are most efficient when used as a PostFilter.

For example:

This is an example of 3 regular filters, where all matching documents generated by each are computed up front and cached independently:

q=some keywords
fq=quantity_in_stock:[5 TO *]
fq={!frange l=10 u=100}mul(popularity,price)
fq={!frange cost=200 l=0}pow(mul(sum(1, query('tag:smartphone')), div(1,avg_rating)), 2.3)

These are the same filters run w/o caching. The simple range query on the quantity_in_stock field will be run in parallel with the main query like a traditional lucene filter, while the 2 frange filters will only be checked against each document has already matched the main query and the quantity_in_stock range query — first the simpler mul(popularity,price) will be checked (because of it’s implicit cost=100) and only if it matches will the final very complex filter (with it’s higher cost=200) be checked.

q=some keywords
fq={!cache=false}quantity_in_stock:[5 TO *]
fq={!frange cache=false l=10 u=100}mul(popularity,price)
fq={!frange cache=false cost=200 l=0}pow(mul(sum(1, query('tag:smartphone')), div(1,avg_rating)), 2.3)

logParamsList Parameter

By default, Solr logs all parameters of requests. Set this parameter to restrict which parameters of a request are logged. This may help control logging to only those parameters considered important to your organization.

For example, you could define this like:

logParamsList=q,fq

And only the 'q' and 'fq' parameters will be logged.

If no parameters should be logged, you can send logParamsList as empty (i.e., logParamsList=).

This parameter not only applies to query requests, but to any kind of request to Solr.

echoParams Parameter

The echoParams parameter controls what information about request parameters is included in the response header.

The echoParams parameter accepts the following values:

explicit: This is the default value. Only parameters included in the actual request, plus the _ parameter (which is a 64-bit numeric timestamp) will be added to the params section of the response header.
all: Include all request parameters that contributed to the query. This will include everything defined in the request handler definition found in solrconfig.xml as well as parameters included with the request, plus the _ parameter. If a parameter is included in the request handler definition AND the request, it will appear multiple times in the response header.
none: Entirely removes the "params" section of the response header. No information about the request parameters will be available in the response.

Here is an example of a JSON response where the echoParams parameter was not included, so the default of explicit is active. The request URL that created this response included three parameters - q, wt, and indent:

{
  "responseHeader": {
    "status": 0,
    "QTime": 0,
    "params": {
      "q": "solr",
      "indent": "true",
      "wt": "json",
      "_": "1458227751857"
    }
  },
  "response": {
    "numFound": 0,
    "start": 0,
    "docs": []
  }
}

This is what happens if a similar request is sent that adds echoParams=all to the three parameters used in the previous example:

{
  "responseHeader": {
    "status": 0,
    "QTime": 0,
    "params": {
      "q": "solr",
      "df": "text",
      "preferLocalShards": "false",
      "indent": "true",
      "echoParams": "all",
      "rows": "10",
      "wt": "json",
      "_": "1458228887287"
    }
  },
  "response": {
    "numFound": 0,
    "start": 0,
    "docs": []
  }
}

Query Syntax and Parsing The Standard Query Parser