Search Documents (Azure Cognitive Search REST API)

Queries in Azure Cognitive Search are implemented using the .NET library or REST API. This article is about using the REST API. For an overview of query construction and methodologies see Queries in Azure Cognitive Search. To learn about query engine and processing, see How full text search works in Azure Cognitive Search.

In the REST API, a Search Documents operation is issued as a GET or POST request and specifies query parameters that give the criteria for selecting matching documents.

GET https://[service name][index name]/docs?[query parameters]  
api-key: [admin key]  
POST https://[service name][index name]/docs/search?api-version=[api-version]  
Content-Type: application/json  
api-key: [admin or query key]  

When to use POST instead of GET

When you use HTTP GET to call the Search Documents API, you need to be aware that the length of the request URL cannot exceed 8 KB. This is usually enough for most applications. However, some applications produce very large queries or OData filter expressions. For these applications, using HTTP POST is a better choice because it allows larger filters and queries than GET. With POST, the number of terms or clauses in a query is the limiting factor, not the size of the raw query since the request size limit for POST is approximately 16 MB.


Even though the POST request size limit is very large, search queries and filter expressions cannot be arbitrarily complex. See Lucene query syntax in Azure Cognitive Search and OData Expression Syntax for Azure Cognitive Search for more information about search query and filter complexity limitations.


HTTPS is required for service requests. The Search Documents request can be constructed using the GET or POST methods.

The request URI specifies which index to query, for all documents that match the query parameters. Parameters are specified on the query string in the case of GET requests, and in the request body in the case of POST requests.

URL-encoding recommendations

As a best practice when creating GET requests, remember to URL-encode specific query parameters when calling the REST API directly. For Search Documents operations, this includes:

  • search

  • $filter

  • facet

  • highlightPreTag

  • highlightPostTag

URL encoding is only recommended on the above query parameters. If you inadvertently URL-encode the entire query string (everything after the ?), requests will break.

Also, URL encoding is only necessary when calling the REST API directly using GET. No URL encoding is necessary when calling Search Documents using POST, or when using the Azure Cognitive Search .NET client library, which handles URL encoding for you.

Query Parameters

A query accepts several parameters that provide query criteria and also specify search behavior. You provide these parameters in the URL query string when calling via GET, and as JSON properties in the request body when calling via POST. The syntax for some parameters is slightly different between GET and POST. These differences are noted as applicable below.

search=[string] (optional)

The text to search for. All searchable fields are searched by default unless searchFields is specified. When searching searchable fields, the search text itself is tokenized, so multiple terms can be separated by white space (for example: search=hello world). To match any term, use * (this can be useful for boolean filter queries). Omitting this parameter has the same effect as setting it to *. See Simple query syntax for specifics on the search syntax.


The results can sometimes be surprising when querying over searchable fields. The tokenizer includes logic to handle cases common to English text like apostrophes, commas in numbers, and so forth. For example, search=123,456 will match a single term 123,456 rather than the individual terms 123 and 456, since commas are used as thousand-separators for large numbers in English. For this reason, we recommend using white space rather than punctuation to separate terms in the search parameter.

searchMode=any | all (optional)

Defaults to any. Specifies whether any or all of the search terms must be matched in order to count the document as a match.

searchFields=[string] (optional)

The list of comma-separated field names to search for the specified text. Target fields must be marked as searchable.

queryType=simple | full (optional)

Defaults to simple. When set to simple, search text is interpreted using a simple query language that allows for symbols such as +, * and "". Queries are evaluated across all searchable fields (or fields indicated in searchFields) in each document by default.

When the query type is set to full, search text is interpreted using the Lucene query language which allows field-specific and weighted searches. See Simple query syntax in Azure Cognitive Search and Lucene query syntax in Azure Cognitive Search for specifics on the search syntaxes.


Range search in the Lucene query language is not supported in favor of $filter which offers similar functionality.

$skip=# (optional)

The number of search results to skip. When calling via POST, this parameter is named skip instead of $skip. This value cannot be greater than 100,000. If you need to scan documents in sequence, but cannot use $skip due to this limitation, consider using $orderby on a field that has unique values for every document in the index (like the document key, for example) and $filter with a range query instead.

$top=# (optional)

The number of search results to retrieve. This defaults to 50. When calling via POST, this parameter is named top instead of $top. If you specify a value greater than 1000 and there are more than 1000 results, only the first 1000 results will be returned, along with a link to the next page of results (see @odata.nextLink in the example below).

Azure Cognitive Search uses server-side paging to prevent queries from retrieving too many documents at once. The default page size is 50, while the maximum page size is 1000. This means that by default Search Documents returns at most 50 results if you don't specify $top. If there are more than 50 results, the response includes information to retrieve the next page of at most 50 results (see @odata.nextLink and @search.nextPageParameters in the Examples below. Similarly, if you specify a value greater than 1000 for $top and there are more than 1000 results, only the first 1000 results are returned, along with information to retrieve the next page of at most 1000 results.

$count=true | false

Optional, defaults to false. When calling via POST, this parameter is named count instead of $count. Specifies whether to fetch the total count of results. This is the count of all documents that match the search and $filter parameters, ignoring $top and $skip. Setting this value to true may have a performance impact. The count returned is an approximation. If you’d like to get only the count without any documents, you can use $top=0.

$orderby=[string] (optional)

A list of comma-separated expressions to sort the results by. When calling via POST, this parameter is named orderby instead of $orderby. Each expression can be either a field name or a call to the geo.distance() function. Each expression can be followed by asc to indicate ascending, and desc to indicate descending. The default is ascending order. Ties will be broken by the match scores of documents. If no $orderby is specified, the default sort order is descending by document match score. There is a limit of 32 clauses for $orderby.

$select=[string] (optional)

A list of comma-separated fields to include in the result set. Only fields marked as retrievable can be included in this clause. If unspecified or set to *, all fields marked as retrievable in the schema are included in the projection. When calling via POST, this parameter is named select instead of $select.

facet=[string] (zero or more)

A field to facet by. Optionally, the string may contain parameters to customize the faceting, expressed as comma-separated name:value pairs. When calling via POST, this parameter is named facets instead of facet.

Valid parameters are:

  • count (max # of facet terms; default is 10). There is no upper limit on the number of terms, but higher values incur a corresponding performance penalty, especially if the faceted field contains a large number of unique terms. For example, facet=category,count:5 gets the top five categories in facet results. If the count parameter is less than the number of unique terms, the results may not be accurate. This is due to the way faceting queries are distributed across shards. Increasing count generally increases the accuracy of term counts, but at a performance cost.

  • sort (one of count to sort descending by count, -count to sort ascending by count, value to sort ascending by value, or -value to sort descending by value). For example, facet=category,count:3,sort:count gets the top three categories in facet results in descending order by the number of documents with each city name. If the top three categories are Budget, Motel, and Luxury, and Budget has 5 hits, Motel has 6, and Luxury has 4, then the buckets will be in the order Motel, Budget, Luxury. facet=rating,sort:-value produces buckets for all possible ratings, in descending order by value. For example, if the ratings are from 1 to 5, the buckets will be ordered 5, 4, 3, 2, 1, irrespective of how many documents match each rating.

  • values (pipe-delimited numeric or Edm.DateTimeOffset values specifying a dynamic set of facet entry values). For example, facet=baseRate,values:10 | 20 produces three buckets: one for base rate 0 up to but not including 10, one for 10 up to but not including 20, and one for 20 and higher. facet=lastRenovationDate,values:2010-02-01T00:00:00Z produces two buckets: one for hotels renovated before February 2010, and one for hotels renovated February 1st, 2010 or later.

  • interval (integer interval greater than 0 for numbers, or minute, hour, day, week, month, quarter, year for date time values). For example, facet=baseRate,interval:100 produces buckets based on base rate ranges of size 100. If base rates are all between $60 and $600, there will be buckets for 0-100, 100-200, 200-300, 300-400, 400-500, and 500-600. facet=lastRenovationDate,interval:year produces one bucket for each year when hotels were renovated.

  • timeoffset ([+-]hh:mm, [+-]hhmm, or [+-]hh). If used, the timeoffset parameter must be combined with the interval option, and only when applied to a field of type Edm.DateTimeOffset. The value specifies the UTC time offset to account for in setting time boundaries. For example: facet=lastRenovationDate,interval:day,timeoffset:-01:00 uses the day boundary that starts at 01:00:00 UTC (midnight in the target time zone).

count and sort can be combined in the same facet specification, but they cannot be combined with interval or values, and interval and values cannot be combined together.

Interval facets on date time are computed based on the UTC time if timeoffset is not specified. For example: for facet=lastRenovationDate,interval:day, the day boundary starts at 00:00:00 UTC.

$filter=[string] (optional)

A structured search expression in standard OData syntax. When calling via POST, this parameter is named filter instead of $filter. See OData Expression Syntax for Azure Cognitive Search for details on the subset of the OData expression grammar that Azure Cognitive Search supports.

highlight=[string] (optional)

A set of comma-separated field names used for hit highlights. Only searchable fields can be used for hit highlighting. By default, Azure Cognitive Search returns up to 5 highlights per field. The limit is configurable per field by appending -<max # of highlights> following the field name. For example, highlight=title-3,description-10 returns up to 3 highlighted hits from the title field and up to 10 hits from the description field. <max # of highlights> must be an integer between 1 and 1000 inclusive.

highlightPreTag=[string] (optional)

Defaults to </em>. A string tag that appends to hit highlights. Must be set with highlightPostTag. Reserved characters in URL must be percent-encoded (for example, %23 instead of #).

highlightPostTag=[string] (optional)

Defaults to </em>. A string tag that appends to hit highlights. Must be set with highlightPreTag. Reserved characters in URL must be percent-encoded (for example, %23 instead of #).

scoringProfile=[string] (optional)

The name of a scoring profile to evaluate match scores for matching documents in order to sort the results.

scoringParameter=[string] (zero or more)

Indicates the values for each parameter defined in a scoring function (such as referencePointParameter) using the format name-value1,value2,... When calling via POST, this parameter is named scoringParameters instead of scoringParameter. Also, you specify it as a JSON array of strings where each string is a separate name-values pair.

  • For scoring profiles that include a function, separate the function from its input list with a - character. For example, a function called "mylocation" would be &scoringParameter=mylocation--122.2,44.8. The first dash separates the function name from the value list, while the second dash is part of the first value (longitude in this example).

  • For scoring parameters such as for tag boosting that can contain commas, you can escape any such values in the list using single quotes. If the values themselves contain single quotes, you can escape them by doubling. Suppose you have a tag boosting parameter called "mytag" and you want to boost on the tag values "Hello, O'Brien" and "Smith", the query string option would then be &scoringParameter=mytag-'Hello, O''Brien',Smith. Quotes are only required for values that contain commas.

minimumCoverage (optional, defaults to 100)

A number between 0 and 100 indicating the percentage of the index that must be covered by a search query in order for the query to be reported as a success. By default, the entire index must be available or the Search operation will return HTTP status code 503. If you set minimumCoverage and Search succeeds, it will return HTTP 200 and include a @search.coverage value in the response indicating the percentage of the index that was included in the query.


Setting this parameter to a value lower than 100 can be useful for ensuring search availability even for services with only one replica. However, not all matching documents are guaranteed to be present in the search results. If search recall is more important to your application than availability, then it's best to leave minimumCoverage at its default value of 100.

api-version=[string] (required)

The api-version parameter is required. See API versioning in Azure Cognitive Search for a list of available versions. For this operation, the api-version is specified as a query parameter in the URL regardless of whether you call Search Documents with GET or POST.

Request Headers

The following table describes the required and optional request headers.

Request Header Description
Accept: Specifies the content type of the results returned by the service. This value must be set to application/json.
api-key The api-key is used to authenticate the request to your Search service. It is a string value, unique to your service URL. The Search Documents request can specify either an admin key or query key for api-key.

You will also need the service name to construct the request URL. You can get the service name and api-key from your service dashboard in the Azure portal.

Request Body

For GET: None.


     "count": true | false (default),  
     "facets": [ "facet_expression_1", "facet_expression_2", ... ],  
     "filter": "odata_filter_expression",  
     "highlight": "highlight_field_1, highlight_field_2, ...",  
     "highlightPreTag": "pre_tag",  
     "highlightPostTag": "post_tag",  
     "minimumCoverage": # (% of index that must be covered to declare query successful; default 100),  
     "orderby": "orderby_expression",  
     "scoringParameters": [ "scoring_parameter_1", "scoring_parameter_2", ... ],  
     "scoringProfile": "scoring_profile_name",  
     "search": "simple_query_expression",  
     "searchFields": "field_name_1, field_name_2, ...",  
     "searchMode": "any" (default) | "all",  
     "select": "field_name_1, field_name_2, ...",  
     "skip": # (default 0),  
     "top": #  

Continuation of Partial Search Responses

Sometimes Azure Cognitive Search can't return all the requested results in a single Search response. This can happen for different reasons, such as when the query requests too many documents by not specifying $top or specifying a value for $top that is too large. In such cases, Azure Cognitive Search will include the @odata.nextLink annotation in the response body, and also @search.nextPageParameters if it was a POST request. You can use the values of these annotations to formulate another Search request to get the next part of the search response. This is called a continuation of the original Search request, and the annotations are generally called continuation tokens. See the example in Response below for details on the syntax of these annotations and where they appear in the response body.

The reasons why Azure Cognitive Search might return continuation tokens are implementation-specific and subject to change. Robust clients should always be ready to handle cases where fewer documents than expected are returned and a continuation token is included to continue retrieving documents. Also note that you must use the same HTTP method as the original request in order to continue. For example, if you sent a GET request, any continuation requests you send must also use GET (and likewise for POST).


The purpose of @odata.nextLink and @search.nextPageParameters is to protect the service from queries that request too many results, not to provide a general mechanism for paging. If you want to page through results, use $top and $skip together. For example, if you want pages of size 10, your first request should have $top=10 and $skip=0, the second request should have $top=10 and $skip=10, the third request should have $top=10 and $skip=20, and so on.


Status Code: 200 OK is returned for a successful response.

  "@odata.count": # (if $count=true was provided in the query),
  "@search.coverage": # (if minimumCoverage was provided in the query),
  "@search.facets": { (if faceting was specified in the query)
    "facet_field": [
        "value": facet_entry_value (for non-range facets),
        "from": facet_entry_value (for range facets),
        "to": facet_entry_value (for range facets),
        "count": number_of_documents
  "@search.nextPageParameters": { (request body to fetch the next page of results if not all results could be returned in this response and Search was called with POST)
    "count": ... (value from request body if present),
    "facets": ... (value from request body if present),
    "filter": ... (value from request body if present),
    "highlight": ... (value from request body if present),
    "highlightPreTag": ... (value from request body if present),
    "highlightPostTag": ... (value from request body if present),
    "minimumCoverage": ... (value from request body if present),
    "orderby": ... (value from request body if present),
    "scoringParameters": ... (value from request body if present),
    "scoringProfile": ... (value from request body if present),
    "search": ... (value from request body if present),
    "searchFields": ... (value from request body if present),
    "searchMode": ... (value from request body if present),
    "select": ... (value from request body if present),
    "skip": ... (page size plus value from request body if present),
    "top": ... (value from request body if present minus page size),
  "value": [
      "@search.score": document_score (if a text query was provided),
      "@search.highlights": {
        field_name: [ subset of text, ... ],
      key_field_name: document_key,
      field_name: field_value (retrievable fields or specified projection),
  "@odata.nextLink": (URL to fetch the next page of results if not all results could be returned in this response; Applies to both GET and POST)


You can find additional examples in OData Expression Syntax for Azure Cognitive Search.

  1. Search the Index sorted descending by date:

    GET /indexes/hotels/docs?search=*&$orderby=LastRenovationDate desc&api-version=2019-05-06 
    POST /indexes/hotels/docs/search?api-version=2019-05-06 
          "search": "*",  
          "orderby": "LastRenovationDate desc"
  2. In a faceted search, search the index and retrieve facets for categories, ratings, tags, as well as items with baseRate in specific ranges.

    GET /indexes/hotels/docs?search=*&facet=Category&facet=Rating&facet=Tags&facet=Rooms/BaseRate,values:80|150|220&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06
          "search": "test",  
          "facets": [ "Category", "Rating", "Tags", "Rooms/BaseRate,values:80|150|220" ]  

    Notice the last facet is on a sub-field. Facets count the parent document (Hotels) and not intermediate sub-documents (Rooms), so the response will determine the number of hotels that have any rooms in each price bucket.

  3. Using a filter, narrow down the previous faceted query result after the user clicks on Rating 3 and category "Motel".

    GET /indexes/hotels/docs?search=*&facet=tags&facet=Rooms/BaseRate,values:80|150|220&$filter=Rating eq 3 and Category eq 'Motel'&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06 
          "search": "test",  
          "facets": [ "tags", "Rooms/BaseRate,values:80|150|220" ],  
          "filter": "Rating eq 3 and Category eq 'Motel'"  
  4. In a faceted search, set an upper limit on unique terms returned in a query. The default is 10, but you can increase or decrease this value using the count parameter on the facet attribute. This example returns facets for city, limited to 5.

    GET /indexes/hotels/docs?search=*&facet=Address/City,count:5&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06 
          "search": "test",  
          "facets": [ "Address/City,count:5" ]  
  5. Search the Index within specific fields (for example, a language field):

    GET /indexes/hotels/docs?search=hôtel&searchFields=Description_fr&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06 
          "search": "hôtel",  
          "searchFields": "Description_fr"
  6. Search the Index across multiple fields. For example, you can store and query searchable fields in multiple languages, all within the same index. If English and French descriptions co-exist in the same document, you can return any or all in the query results:

    GET /indexes/hotels/docs?search=hotel&searchFields=Description,Description_fr&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06
          "search": "hotel",  
          "searchFields": "Description, Description_fr"

    You can only query index at a time. Do not create multiple indexes for each language unless you plan to query one at a time.

  7. Paging - Get the first page of items (page size is 10):

    GET /indexes/hotels/docs?search=*&$skip=0&$top=10&api-version=2019-05-06 
    POST /indexes/hotels/docs/search?api-version=2019-05-06 
          "search": "*",  
          "skip": 0,  
          "top": 10  
  8. Paging - Get the second page of items (page size is 10):

    GET /indexes/hotels/docs?search=*&$skip=10&$top=10&api-version=2019-05-06 
    POST /indexes/hotels/docs/search?api-version=2019-05-06 
          "search": "*",  
          "skip": 10,  
          "top": 10  
  9. Retrieve a specific set of fields:

    GET /indexes/hotels/docs?search=*&$select=HotelName,Description&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06  
          "search": "*",  
          "select": "HotelName, Description"
  10. Retrieve documents matching a specific filter expression:

    GET /indexes/hotels/docs?$filter=(Rooms/BaseRate ge 60 and Rooms/BaseRate lt 300) or HotelName eq 'Fancy Stay'&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06  
          "filter": "(Rooms/BaseRate ge 60 and Rooms/BaseRate lt 300) or HotelName eq 'Fancy Stay'"  
  11. Search the index and return fragments with hit highlights:

    GET /indexes/hotels/docs?search=something&highlight=Description&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06 
          "search": "something",  
          "highlight": "Description"  
  12. Search the index and return documents sorted from closer to farther away from a reference location:

    GET /indexes/hotels/docs?search=something&$orderby=geo.distance(Location, geography'POINT(-122.12315 47.88121)')&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06
          "search": "something",  
          "orderby": "geo.distance(Location, geography'POINT(-122.12315 47.88121)')"
  13. Search the index assuming there's a scoring profile called "geo" with two distance scoring functions, one defining a parameter called "currentLocation" and one defining a parameter called "lastLocation":

    GET /indexes/hotels/docs?search=something&scoringProfile=geo&scoringParameter=currentLocation--122.123,44.77233&scoringParameter=lastLocation--121.499,44.2113&api-version=2019-05-06  
    POST /indexes/hotels/docs/search?api-version=2019-05-06 
          "search": "something",  
          "scoringProfile": "geo",  
          "scoringParameters": [ "currentLocation--122.123,44.77233", "lastLocation--121.499,44.2113" ]  
  14. Find documents in the index using simple query syntax. This query returns hotels where searchable fields contain the terms "comfort" and "location" but not "motel":

    Get /indexes/hotels/docs?search=comfort +location –motel&searchMode=all&api-version=2019-05-06
    POST /indexes/hotels/docs/search?api-version=2019-05-06
          "search": "comfort +location -motel",  
          "searchMode": "all"  


    The use of searchMode=all overrides the default of searchMode=any, ensuring that -motel means "AND NOT" instead of "OR NOT". Without searchMode=all, you get "OR NOT" which expands rather than restricts search results, and this can be counter-intuitive to some users.

  15. Find documents in the index using Lucene query syntax (see Lucene query syntax in Azure Cognitive Search). This query returns hotels where the category field contains the term "budget" and all searchable fields containing the phrase "recently renovated". Documents containing the phrase "recently renovated" are ranked higher as a result of the term boost value (3)

    GET /indexes/hotels/docs?search=Category:budget AND \"recently renovated\"^3&searchMode=all&api-version=2019-05-06&querytype=full

    POST /indexes/hotels/docs/search?api-version=2019-05-06
         "search": "Category:budget AND \"recently renovated\"^3",  
          "queryType": "full",  
          "searchMode": "all"  

See also

Azure Cognitive Search REST APIs
HTTP status codes (Azure Cognitive Search)
OData Expression Syntax for Azure vSearch
Simple query syntax in Azure Cognitive Search
Azure Cognitive Search .NET library